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Posted By: Jimmy66 Ignition problems- 305E V6 - Mon Jan 25 2021 05:20 AM
Hello! New member here. I’m a guitar builder and repair man, not a mechanic by any means. I had the chance to get the truck we camped in as a kid from my dad and I took it, so bare with my ignorance, please I recently revived my family’s 1966 GMC 3/4 ton pick up, (with a cab over open road camper and all). It hadn’t run in about 33 years. Worked on it over the summer, got it running and drove it the short 5 minutes from my parents to my house. It made it fine. I was replacing things as I went, carb rebuild, fuel pump and fuel filter, thermostat, master cylinder, bled breaks, etc. I was just taking it around my neighborhood every few days to keep it moving and one day it started stalling out on me and acting like it was starved for fuel.I barely made it home.
Since then it tries, but has not started. My first thought was I didn’t clean fuel tank well enough, so I’ve replaced the fuel tank and all the rubber line, as well as blowing out steel lines with compressed air, put an in line fuel filter, carb is getting gas. So I did a tune up, all new plugs, points, coil, condenser, rotor, wires, cap. Still wouldn’t start. I’m not getting blue spark, orange weak spark. Just installed high power alternator, and pertronix electronic ignition, and came across this resistor wire! Is it possible this has been my issue all along? I’m going to install the pertronix power relay that bypasses the resistor wire, it’s on its way. Any input would be greatly appreciated. I’m very much a novice. Thanks! - Jimmy
Posted By: Hambone Re: Ignition problems- 305E V6 - Mon Jan 25 2021 01:03 PM
Welcome Jimmy. Those camper trucks are good to save. Likely some extra options on that truck. We need pictures.

We will see what the engine experts have to say, but it sounds like you are hitting the right chords.
Confirm you cleaned the small filter in the input to the carb. My first thought is fuel, but if you cleaned and checked the tank, lines and carb then we shortly can check that off the list.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Mon Jan 25 2021 01:49 PM
Take everything off that is associated with Pertronix. Go back to original or get a GM HEI with the coil in the cap. Some have good results with Pertronix but a significant amount of folks don’t. Weak orange spark won’t do it.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Mon Jan 25 2021 02:48 PM
Thanks for the replies. To be fair to the Pertronix, I had weak orange spark before I put it in. I will wait for the relay to get here and try it, if that works, i will assume the resistor wire was my problem. If not, I will remove it all. I appreciate it. I have a couple knowledgeable friends here in Albuquerque, but I’m mostly experimenting, learning as I go.👍🏻
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Mon Jan 25 2021 03:32 PM
Here’s a picture of the truck. Unfortunately, my parents used the camper as storage for years, and there were leaks they didn’t know about. There is quite a bit of water damage and mold, so I am probably going to get rid of it once the truck is running, and just keep the truck.

Attached picture 07162E39-AA40-43DC-8C90-5796C5E7C11C.jpeg
Posted By: Hotrod Lincoln Re: Ignition problems- 305E V6 - Mon Jan 25 2021 04:08 PM
Ditto on the "trash the Pertronix" advice. I'm not aware of a factory HEI distributor that will replace a 305 V6 distributor without some pretty extensive machining, but there are two types of Pertronix units- - - -the ones that have failed, and the ones that are getting ready to! A hot blue spark is only necessary if you want to replace distributor caps and rotors on a regular basis. If you're using resistor type ignition wires (a good idea) a normal spark will be orange/yellow looking.
Jerry
Posted By: bartamos Re: Ignition problems- 305E V6 - Mon Jan 25 2021 07:52 PM
The dreaded "replaced everything but still won't start". It is true there is no drop-in HEI for these motors.

They use a bypass resistive ignition system as do most 12V points motors of the day.

I will have about 5-10 questions when you are ready. Test the battery or get a new one pretty quick.

Take off the camper and take off the spare from front before I go nuts smile. Hopefully they kept the tailgate. Keep the mirrors, they can be worth money. This is a really good truck with a good motor. Long lasting, powerful motor. I like them for a daily driver truck. But the motor is a boat anchor. I say that with all respect to GMC engineers. The motor is a design masterpiece. Except it's maxed out at 3800 RPM. Approaching 900 lb weight without trans.
60-66 GMC's are fairly rare, especially if it has factory options. Yours seems to be a non deluxe variety. That's OK. The originality of your truck makes it very valuable to some folks, so keep that in mind with all your changes. The GMC crowd is very loyal. 1966 is a premium year. Last year for that body style.

Pertronix is OK. Not necessary, but OK. The newer II and III are better than the old Ignitor I. THE "POWER RELAY" IS A 100% SCAM. If it works, it means you did not install the Pertronix correctly in the first place.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 12:05 AM
Thanks Bartamos-

Battery is new, 4 months old, and is reading 12.6v on a meter.

Tailgate and mirrors are long gone. It was purchased with the camper on it from an Albuquerque dealer who packaged them that way. Had badges made for the side that say "Camper Liner". Dan Ely Buick.

I will take the spare off when I take the camper off. Thats one of the old split rims. It has new wheels and tires now.

The Pertronix I installed is a II.

So far I have not changed anything that can't be changed back to original, and I'm keeping everything I take out for the time being.

Fire away with your questions.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 10:26 AM
OK Jimmy, lets get her figured out. You said you had "yellow spark" before and after the Pertronix. Please be sure to answer every question carefully and thoroughly.
1. You said new coil. When was new coil added? During the points ignition testing or when Pertronix was installed? Did this new coil come with the Pertronix or is it one they recommended? or is it just a generic coil? What words appear on it? What do you know about it's specs?
2. What did you do with the resistance wire? What, if anything, is it wired to right now?
3. Are you saying the starter turns over the motor at a good rate? Is the yellow spark seen across a removed spark plug during cranking or ?
4. Did you, at any point, take out the distributor?
5. Did you add any "ignition" wires? or starter wires? or any wires?
6. What do the Pertronix instructions say about the resistance wire? Did you adjust the gap on the Pertronix to .030 for sure.
7. Is there absolutely no fire when cranked? No backfire at carb or tail pipe? No attempt to start at all? No sputter or odd noise?
8. Can you post good, well lit, clear pics of the distributor and it's wires before you disturb them or add this "relay"? Can you describe exactly how the Pertronix unit and the ignition coil are wired now?
9. If there is a special Pertronix for V6, did you get the correct unit? What is the Pertronix part number?

Feel free to post any other pics of the motor.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 04:34 PM
1. You said new coil. When was new coil added?
I added a new coil during points testing, it was an OE Driveworks from advance auto, part #26189
I tried swapping it back for original coil, and there was no change.
I have since installed the Pertronix flamethrower coil to go with Ignitor II


2. What did you do with the resistance wire? What, if anything, is it wired to right now?
It is still wired in place, to positive on coil, and goes into wiring harness. I believe it goes to starter and to plug in firewall. I have not tried turning it over more than once since Pertronix, because wire is not yet bypassed. I tested new alternator, just to make sure it was in correctly.

3. Are you saying the starter turns over the motor at a good rate? Is the yellow spark seen across a removed spark plug during cranking or ?
Yes, it sounds like it is turning in over at a good rate, although my only other thought of a culprit is the starter. Yellow spark seen from a spark plug wire removed at cranking.

4. Did you, at any point, take out the distributor? no

5. Did you add any "ignition" wires? or starter wires? or any wires? no

6. What do the Pertronix instructions say about the resistance wire?
Instructions said to remove resistance wire or install relay. I opted for relay incase I had to put it back, and because I don't want to slice up the wiring harness.

Did you adjust the gap on the Pertronix to .030 for sure? as best I can tell, I used the feeler gauge.

7. Is there absolutely no fire when cranked? No backfire at carb or tail pipe? No attempt to start at all? No sputter or odd noise?
no backfire, occasional sputter like it wants to start.

8. Can you post good, well lit, clear pics of the distributor and it's wires before you disturb them or add this "relay"?
we got a snow storm last night, so as soon as it warms up this afternoon, I will take pictures.

Can you describe exactly how the Pertronix unit and the ignition coil are wired now?
I followed Pertronix directions exactly, their leads from unit come to ground and positive posts on coil, and the yellow wire and resistance wire are also on positive post for coil. inside distributor there is a ground to plate, and the unit itself.

9. If there is a special Pertronix for V6, did you get the correct unit? What is the Pertronix part number?
Pertronix part number is 36-2945 Ignitor II for 6 cylinder, I didn't think of that, I suppose it could be for inline 6?

Feel free to post any other pics of the motor.
Albuquerque snow doesn't last long, I'll update with some pics later today.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 07:17 PM
@ no. 3 answer...........describe "spark plug wire" test. How was this test done exactly. What do you mean by spark plug wire? Where was the spark plug? What part of what wire? at plug, at distributor?????????? From what to what did the spark jump? How far did it jump?

@ No. 8 answer.............what is the yellow wire? What color is the resistance wire?

Have you installed the relay?

36-2945 has NO matches on websearch or the Pertronix website????????????? PLEASE PROVIDE LINK. Search brings up 1162A for L6 and V6 GMC. Maybe your number is superseded or you are giving a vendor number. Where did you buy it and how long ago?

The alternator has nothing to do with starting.

Do not disturb any wiring until I get done thinking and asking and seeing pics.
Posted By: coilover Re: Ignition problems- 305E V6 - Tue Jan 26 2021 07:40 PM
The first thing I would do is ELIMINATE the truck wiring system. Make a 12g jumper wire to run from battery + to coil +. If spark color improves or if it fires and runs good then trace down the trouble. We also have a freon jug gas can with a regulator so pressure can be set from zero to 150psi to cover both carbs and fuel injection. This eliminates the factory fuel system to isolate the trouble if there. KISS
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 07:54 PM
[ no. 3 answer...........describe "spark plug wire" test. How was this test done exactly. What do you mean by spark plug wire? Where was the spark plug? What part of what wire? at plug, at distributor?????????? From what to what did the spark jump? How far did it jump?
The ol' screwdriver in the plug wire, (at the plug end, not cap), make it arc to metal on the engine.

@ No. 8 answer.............what is the yellow wire? What color is the resistance wire?
I can't find the exact wiring diagram for that truck, but I believe the yellow wire comes from the starter, and the resistor wire is clear insulation with a visible braided wire shielding below.

Have you installed the relay?
I don't have the relay yet

I know alternator has nothing to do with starting, I was making sure it was wired in right and belt was tight.
I won't disturb any wiring, and will have pics soon.
thank you
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 07:56 PM
thanks Evan, I'm taking it one step at a time, due to my ignorance, I will keep all that in mind.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 08:31 PM
You forgot to answer about the part number 36-2945.

1. As a point of info: On a 66 GMC there was one wire from ignition "on" terminal to starter "R" terminal. This was the resistance wire. Then there was a yellow wire from the "R" terminal on the starter to coil positive.

2. The Ignitor II instructions I have say that you can remove resistance wire or not. Do you agree? I.E. Figure 2.

3. Here is the disturbing part and may be your problem, once I am sure what you said. Regarding the positive terminal on the coil: you said you have the Pertronix wire (probably red), a yellow wire, and the "resistance wire" on that terminal. That would be three wires. Is that what you have or not? Here are your words:

I followed Pertronix directions exactly, their leads from unit come to ground and positive posts on coil, and the yellow wire and resistance wire are also on positive post for coil. inside distributor there is a ground to plate, and the unit itself.

Very glad you are NOT doing ANYTHING until I am done with troubleshooting.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 08:32 PM
[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27051/filename/IMG_0524.jpeg[/img][img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27052/filename/IMG_0525.jpeg[/img][img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27053/filename/IMG_0522.jpeg[/img][img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27054/filename/IMG_0527.jpeg[/img][img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27055/filename/IMG_0528.jpeg[/img]

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Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 08:34 PM
Read and answer my last post. I think I see three wires. So this is the problem. Now we are getting somewhere.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 08:56 PM
part number is 91162A
Ignitor II for telco 6cyl w vac advance


1. As a point of info: On a 66 GMC there was one wire from ignition "on" terminal to starter "R" terminal. This was the resistance wire. Then there was a yellow wire from the "R" terminal on the starter to coil positive. Good to know. thanks

2. The Ignitor II instructions I have say that you can remove resistance wire or not. Do you agree? I.E. Figure 2.
I agree, however it says, 'All external resistors should be removed to achieve optimum performance'. It also says, minimum voltage is 8v, I am getting 5.6 from positive coil terminal. Thats why I was assuming I have to bypass or remove.

3. Here is the disturbing part and may be your problem, once I am sure what you said. Regarding the positive terminal on the coil: you said you have the Pertronix wire (probably red), a yellow wire, and the "resistance wire" on that terminal. That would be three wires. Is that what you have or not? Here are your words:

I followed Pertronix directions exactly, their leads from unit come to ground and positive posts on coil, and the yellow wire and resistance wire are also on positive post for coil. inside distributor there is a ground to plate, and the unit itself.
Leads to coil positive are: Red from Pertronix, and one hoop connector with yellow and resistor wire. that's how it was when I got it, and it ran with those wires going to original coil.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 09:02 PM
OK stand by
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 09:06 PM
I am off to go to work for the afternoon. I have a couple other pictures that I can upload here: [img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27057/filename/hood.jpg[/img]

[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27058/filename/IMG_0523.jpeg[/img]

[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27059/filename/IMG_0526.jpeg[/img]

[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27060/filename/IMG_0529.jpeg[/img]

first and last are just for fun. hood with last night's snow, and an interior shot, for the curious.

Attached picture hood.jpg
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Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 09:20 PM
There are several options. I don't know which you can do. I think you are savvy enough to do what needs to be done.
First step:
1. We don't want to mess up the harness or add wires yet if we don't need to SO......... how many wires are on the "R" terminal on the starter? What color are they?
2. 5.6V with ignition to "on"? How did you hook up the meter leads? Where on the truck did you place the leads for the measurement?
3. What is the voltage at the starter "R" with ignition on?
FIY: The ignition switch has "Ignition on" position and a ignition "Start" position, which is a spring loaded position. Just so you know what I mean when I say "on"..... I don't mean start.

FYI: There is a big honking cable to the starter, you know that. There is one wire on the "S" terminal. We are interested in the "R" terminal right now. Let me know. A pic or two is nice.
It would be VERY helpful if you could figure out where the yellow and companion wire, that you have on the coil, goes. Does it look like someone did that or does it look factory? Don't think it's factory because yellow is so big. At any rate, it's not per 1966 wiring diagram. We will fix that.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 10:01 PM
I will do this first thing tomorrow.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Jan 26 2021 11:21 PM
Too bad. Almost there. Then stop. Bad idea.
Posted By: Hambone Re: Ignition problems- 305E V6 - Tue Jan 26 2021 11:39 PM
Nice looking dash. I want to see the entire truck.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Jan 26 2021 11:55 PM
I had to go to work.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 12:22 AM
Work? Oh! I forgot about going to work, it's been so long. Sorry.

Wow very nice. Original dash, original seats and original floor matt. Factory firewall markings. Everybody likes that. See you tomorrow sometime.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 04:37 PM
First step:
1. We don't want to mess up the harness or add wires yet if we don't need to SO......... how many wires are on the "R" terminal on the starter? What color are they?
based on my pictures, it seems there is only the yellow wire or the R terminal. it goes into a harness, and to the positive. I think its the hot wire. The Resistance wire doesn't seem to be at starter. it comes up the harness to the coil positive, and also seems to continue in harness to plug in firewall.

[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27094/filename/IMG_0535.jpeg[/img]
[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27095/filename/IMG_0539.jpeg[/img]
[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27097/filename/IMG_0541.jpeg[/img]
[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27093/filename/IMG_0542.jpeg[/img]

2. 5.6V with ignition to "on"? How did you hook up the meter leads? Where on the truck did you place the leads for the measurement?
I put a jumper from negative post on coil to ground, I put black lead from meter on negative, red on positive, turned ignition to 'on'.

3. What is the voltage at the starter "R" with ignition on?
11.9 to 12.
battery reads 12.2 with ignition on.


FIY: The ignition switch has "Ignition on" position and a ignition "Start" position, which is a spring loaded position. Just so you know what I mean when I say "on"..... I don't mean start.

FYI: There is a big honking cable to the starter, you know that. There is one wire on the "S" terminal. We are interested in the "R" terminal right now. Let me know. A pic or two is nice.
It would be VERY helpful if you could figure out where the yellow and companion wire, that you have on the coil, goes. Does it look like someone did that or does it look factory? Don't think it's factory because yellow is so big. At any rate, it's not per 1966 wiring diagram. We will fix that.

It looks factory, buy I don't know for sure.


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Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 07:42 PM
1. When checking voltage, you just touch the red meter lead to the place/terminal you want to check and touch the black meter lead to good, clean shinny motor metal, body metal or frame metal. You don't add a jumper or touch other posts. If you are testing a component to see if it is bad, there may be different meter hookups.
2. So lets try this again with meter as I described. What is voltage at coil pos with ignition off? What is voltage with ignition on?
3. Someone has tried to wire the ignition from a Chevy diagram or a pre 1964 GMC diagram. GMC changed the ignition wiring scheme a little bit. I just want to check the voltage per note 2 before moving forward with solution. Almost there.
4. Is the coil in the pics the Pertronix Flamethrower? What coil is on the motor now? I don't se any logo on it.
5. Battery is checked with ignition OFF. You said it was 12.6 now 12.2 correct? Recheck with ignition off. The battery is checked across the posts. Red meter on pos post, black meter on neg post.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:04 PM
The instructions I followed were what was on the literature that came with Pertronix coil, which is what is in the truck. The logo ended up face down, which is fine with me. I’ll check it again in a bit.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:15 PM
I am not questioning the Pertronix install when I said somebody wired ignition per wrong diagram. I'm talking about the yellow and resistance wire that was already there. Lets get on with the other tests above.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:17 PM
Positive on coil reads 11.94 doing it the way you suggested.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:20 PM
I asked for the test at coil pos with ignition ON and then ignition OFF. Ignition means key on and key off
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:22 PM
It says zero at off. And the instructions I was talking about for Pertronix coil was a test they instruct user to do to check for resistance, not the instructions for install.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:26 PM
Pertronix instructions
[img]https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/download/Number/27102/filename/IMG_0547.jpeg[/img]

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Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:33 PM
Take the yellow and resistance wire pair off of the coil and arrange them where they won't touch anything. Leave Pertronix as you have it. Install a jumper from battery positive post to coil positive. Make sure one end has a alligator clip for fast removal. It will be the only way to turn off motor. When jumper is attached, start truck. Ask any questions before starting, otherwise report what happens. BE SURE you are not out of gas in the truck.

I never got a battery reading with ignition off, across posts.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:44 PM
alright, I sure will. the bad news is, I HAVE TO GO TO WORK AGAIN! Gotta leave here in 15 min. I'm gonna run by electronics store and get some bigger wire and alligator clips, (mine is for guitar and Audio, 22awg), I'll make the jumper at work, soldering iron on my repair bench at all times, and do it when I get home.
STAY TUNED
Thanks for all the help.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:53 PM
OK but jumper does not have to be real big, 20 ga or larger
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 08:55 PM
Ok, thanks.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Jan 27 2021 09:49 PM
Glad you work on Guitars. That way you won't get all "strung" out and "fret" over your problems with your "pickup". I will "stay tuned".
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 11:39 PM
Got out of work early so I could catch a little daylight to do the jumper. It did not work. It sounded very much the same as it did before. trying to turn over.
I shot a short video of it trying to start, but I cannot load it. Too big a file. Does this point us towards the starter?

Attached picture My Movie 2.jpg
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Jan 27 2021 11:40 PM
Ha! Just saw last post. Very PUNNY!
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:03 AM
I didn't catch the term "trying to turn over" before now. I think I did ask about that. You said it turns over at a good rate. Then you mentioned starter?

I still did not get a reading from battery. Ignition OFF, measure across posts. Do that ASAP. Read my PM to you.

If it has gas, if coil is direct fed now, if Pertronix unit and coil are good, if battery is good, it HAS TO START.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:13 AM
battery was 12.34 today. it definitely has gas, not all that old.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:26 AM
You said you never took distributor out, Did you ever loosen the clamp and move it? Video sounds a little slow. 12.34 is a little low. Wondering about Pertronix gap and if dizzy does not have good ground. Are Pertronix screws inside tight? May want to charge battery or jump battery for a few seconds. We are working on electrics now. Your initial story was, ran around the block and now won't start. We may switch to fuel delivery after a few more answers.
Your original story did sound like a gas problem but I ignored it when you said weak spark. I could have gotten hornswoggled. We will see after we get a good cranking speed. Jerry did say your spark was OK. We are not partial to Pertronix. I'll explain that someday.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:50 AM
The instructions with Ignitor II says it can change timing by as much as 10 degrees. I have never loosened clamp or moved distributor. Screws on Pertronix were tight, I can recheck.
I will put charger on tonight.

It was running fine, from my folks to my house and around the neighborhood for a couple weeks. It stalled out, and was hard to get going again, it would hardly accelerate, got it into driveway, and it did not start again. new fuel tank, fuel pump (which is new too) was taken out and cleaned, all new rubber, steel lines blown out. Carb cleaned again, (rebuilt before it initially ran), inline filter, so I can see gas is getting to carb, carb does jet gas, pulled a plug today after trying to start and it was wet and smelled of gas. I am less inclined to think fuel, but I very much could be wrong. I assume what put it down could have been debris from tank, which seems to have been handled, and since then another problem, seemingly electrical, has occurred. to try and solve this, I have done new points, rotor, plugs, condenser, coil, cap and wires, no change. THEN I did the Pertronix and new coil. No change.
the battery is 750 cold cranking amps, and is only a few months old, I will top it off with charge.
Thats the whole story as best I can remember.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:53 AM
Did you say fuel pump was "taken out a cleaned" or is that just the tank? The problem is you have done so many things, replaced so many parts, most of which are Chinese. You said you are not a mechanic. So we have to test and not take anything for granted. That's why the process is slow'ish. You are doing amazingly well. Don't assume anything, follow the tests as we go. I'm trying not to jump all over the place with theories. Confusion would ensue.

After checking all connections and you get good cranking speed, try starting one more time. If no start........Motor off, key off, look down throat of carb, have good lighting, work throttle and see if you see a squirt of gas down inside throat.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 12:58 AM
I took pump off and blew it out to make sure nothing was in there, it was only a couple months old. Tank is new.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 01:06 AM
Do the carb throat test above. Don't blow out a fuel pump with compressed air. We are talking a mechanical pump right, not electric? Where are you getting all these parts for a 1966 GMC 305E V6??????????? They are not too common.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 01:13 AM
Will do. I should have some time tomorrow to do all of the above.
have a good night.
Posted By: Hotrod Lincoln Re: Ignition problems- 305E V6 - Thu Jan 28 2021 01:34 AM
Mechanical fuel pumps have one way check valves- - - -they are only supposed to flow from the tank to the carb. If you put much air pressure to the pump in the reverse flow direction, you probably destroyed the check valves. Try disconnecting the fuel line at the carb and see if gas can be pumped into something like an oil bottle at cranking speed.

Battery voltage at open circuit with no load means exactly nothing. Check the voltage at the battery posts (not the cable terminals) after 15 seconds of cranking with the ignition disabled (center coil wire pulled out of the distributor cap and grounded) The voltage WHILE STILL CRANKING should be 10.5 V or more.
Jerry
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 05:05 PM
It was cold last night and I got lazy. Put it on charger this morning. Voltage was good, but only had 74% of a full charge. Letting it get some juice.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 06:46 PM
Point of order: The R terminal on the starter only supplies 12V to coil during cranking (key at "Start" position), then when motor starts, and you let go of the key, the key returns to "ON" position. Then the resistance wire carries the voltage to coil (8-9V). You have said that when you tested the coil with ignition "ON" is was 11.94V. This says something is wrong. Unless you didn't test it correctly as I described. I'll give you the benefit of doubt.

The yellow wire is supposed to be from starter "R" to coil pos. The resistance wire is supposed to come from the ignition switch "ON" terminal. So now I want to know what the voltage is at coil positive with motor cranking. You may need a helper for that. Do that test ASAP.

The fact that there is 11.9/12V with ignition "ON" is OK now that you have Pertronix, but not OK for the points. I just want to make sure there is 12V with key at start/motor cranking. Motor will have weak spark if coil is only getting 8-9V while cranking and Pertronix only getting 8-9V during cranking............or maybe voltage is zero during crank. A low battery or a battery that breaks down will contribute to this or cause all this. I don't pay any attention to posters who say this or that is new. "NEW" has it's own dangers. Lots of bad parts now-a-days and inexperienced installers/owners who damage parts right away. It would be normal for a battery to be low after many tries of starting without recharge however.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 07:32 PM
I went out and did the testing you and Jerry recommended last night, before I read this. Charged battery to 13.6, made sure everything was tight, with yellow and resistor wire off post and with jumper going from battery to positive on coil, it still didn’t start. Video taped that.

Also took center wire from distributor and grounded it. And read voltage at battery while cranking, it never got below 10.9, and I video taped that as well.

Ending voltage on battery after a few cranks was 12.9

I will go out and measure voltage at positive while cranking in a bit. It’s cold, can’t stay out there too long.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 07:49 PM
May be we better wait for better weather. taking too long.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 08:13 PM
Oh I also did carb throat test and video taped that. It is definitely shooting gas.
Going out now to test coil. Had online meeting I had to attend.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Thu Jan 28 2021 08:21 PM
It fluctuated around 10.7-11. I have video of meter while I’m cranking if you want me to send it.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 09:51 PM
Well I thought is would be 12V but I'm not sure, Maybe some voltage drop. So I guess you have gas, spark and compression. The only thing left is timing. It won't start with points or Pertronix, it could be plug wires screwed up on the dizzy, (wires on wrong plugs).
1. Double check firing order vs plug wire routing. Firing order 1-6-5-4-3-2 CW. Spark plug gap .035. RED FLAG>>>> You did take cap off dizzy and you did replace the wires.
2. Check timing 5 deg BTDC. Some of those motor work better up to 10 BTDC
3. Worst case is timing chain slip
4. I believe it's not bad gas from what all you did. But that is another thing common to points and Pertronix no start.
5. This can be a situation that when it died using plugs, it was the capacitor, bad points, gas clog, etc. Then when work was done, new parts added and switched to Pertronix, a new issue emerged at that time. I.E. blown Pertronix component, mistake in dizzy plug wires, etc. or in other words "something got fixed and then something else got broken". This is very hard to find. So using the strategy of what issue "would be common to both points and Pertronix", may not be the best approach. You are performing the basic troubleshooting tests. Eventually, you will discover the gremlin.
You need: Fuel, fire, compression (at the right time)
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Thu Jan 28 2021 10:35 PM
Let me first say, you have been very patient with bartamos and he has been very patient with you. Usually this would have gone off the rail quite awhile ago. That being said and not wishing to step on bartamos’ very comprehensive testing, do the following. Remove #1 spark plug. Place your thumb over the plug hole and have a helper bump the starter/engine around til your thumb gets pushed off the hole by the engine compression. Look at where the timing mark is. It should be pretty close but can be an inch or so one way or the other from the zero mark. Now remove the distributor cap and see where the rotor is pointing. It should be pointing very close to the #1 tower. If not, and you have never removed the distributor, rearrange the plug wires properly and try to start the engine. If it doesn’t start do the test again. It is entirely possible that the timing chain has jumped. Good luck
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Jan 28 2021 11:06 PM
Martin, Good point.

Jimmy: I see by the pictures that the dizzy has the wires in the right order, BUT as Martin says, not sure rotor is pointing at actual no. 1 TDC compression stroke position. So you may have the no.1 wire in the wrong hole. Chances are you need to move them all one tower CW. Leave the spark plug end alone.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 03:53 PM
Ok, thanks Martin, and Bartamos. I am up, its warming up, (30 degrees), and once I'm coffeed up and ready for action I will try moving them all over 1 tower clockwise. If that does not work, I will wait for a friend to come over and try the thumb over the 1 plug hole test. I can't wait to get this thing running and get the camper to the scrap yard.
Posted By: Hotrod Lincoln Re: Ignition problems- 305E V6 - Fri Jan 29 2021 05:00 PM
On a conventional point type ignition system, the only time the voltage at the coil + terminal will show reduced voltage downstream of the ballast resistor is when the points are closed and current is flowing through the coil. If the voltage at the coil is checked with the points open you'll see full battery voltage since no current is going to ground through the points. I have no idea what, if any voltage you'll see if some sort of electronic ignition system is involved. A factory GM HEI system needs to see a cranking signal from the reluctor before any current starts to flow in the coil. That's a "fail safe" built in that the Pertronix doesn't have, to prevent damage in case the ignition switch is left on.
Jerry
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 06:54 PM
When the jumper was used from battery to coil it eliminated any feed problem for the Pertronix and the coil, it still did not start. I see what you mean about not seeing the drop unless points closed. I'm betting/hoping on timing/dizzy plug wires. Last heard from Jimmy three hours ago.

EDIT: It fluctuated between 10.7-11 while cranking. This is with Pertronix. It would have to start, key springs back to on, to allow resisted voltage to take over.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 06:59 PM
Checked firing order of plugs on distributor cap, it was right. Moved the all one tower over clockwise, will not start. Same as before. Going back through this thread I read the spark plug gap is .035, I have .046 in there and they are not adjustable, fixed gap. Could this be the culprit? Bigger gap takes more voltage to jump?
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:26 PM
Yes, I already said your order was right from looking at the pics. Yes, a big gap can prevent starting but .011 should get a fire or two. We don't know why you have that plug? What plug you asked for. Makes me wonder if your other parts are correct for 1966 GMC 305 V6. Parts counter guys or internet application charts probably never heard of that motor.
Find TDC at compression and check rotor. I do it with a remote starter switch (jump the starter switch) and center plug on dizzy removed.

Quote from Pertronix for Ignitor II:
In stock applications, the manufacturer's recommended spark plug, and
spark plug gap will work best. For performance applications, the spark gap
may be increased up to 0.010” from manufacturer’s specifications to take
advantage of the extra energy produced by the Flame-Thrower II coil.
Since PerTronix cannot test every configuration, the end user must
determine what spark plug gap works best for their application.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:31 PM
I ordered those spark plugs online and pick them up at a store, during the height of the pandemic, when you couldn’t go shop anywhere. It’s hard to find auto parts shopping sites that know this engine. It was the best I could do at the time. I plead ignorance.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:33 PM
I moved everything over one, as I said, rotor is currently just past UDC, and rotor is pointing just past where I had 1 originally. Should I put them back?
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:35 PM
I mean crank is currently just past UDC
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:40 PM
Well there are two UDC positions, that's why it has to be the one that appears when there is compression, like you can feel with your thumb at the no. 1 hole. Which is drivers side front. The rotor would be just past no. 1 (lag) so does seem you had in correct place. Tripple check that.
Just past would be just past CW.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:44 PM
If I’m gonna change plugs, should I take them out and then I’ll theoretically be able to turn crank to TDC by hand? Or by belt? Without compression? See where rotor is?
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 07:45 PM
I’ll mark wires for which plug beforehand.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 08:19 PM
Came in to warm up a bit and research the plugs I bought this summer. They are an E3.46, with a .040” fixed gap, maybe not so much of a problem.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 08:22 PM
Specified plug is Delco AC4 or equivalent. There is a long reach and a short reach plug. Either works. The plugs are specific for this motor. 14mm threads. Don't buy Champion plugs.

Delco R44XLS

Re E3 plug, I don't think .005 would be a no fire situation. Your issue is "No fire" not "No start". .040-.035= .005 Can you measure the plug gap of the E3?

TDC hard to detect compression stroke with hand turn.

Motor does turn over easier for starter when plugs removed.

Ignitor II has a warning about using solid copper plug wires on Pertronix? I doubt you bought those.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 08:55 PM
I just mean to turn it without plugs where I can line up TDC and see where rotor is, not for compression stroke. The markings are very hard to see, what exactly am I looking for? What is marking for True Dead Center? I can see IO and UDC at present.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 09:41 PM
UDC= Upper Dead Center...........now called TDC= Top Dead Center. The 10 is ten, 10 degress BTDC (Before Top Dead Center). There is a 1 near UDC, that is TDC dead nuts. Between 1 and 10 is 5 deg BTDC. "Before" is advanced timing. The spec for sea level and the octane used in 1966 is to set timing at the 5. Your motor may run better at 7 or 10 or whatever, All that is later when timed with a light.

Right now you are trying to confirm that rotor and dizzy wires are correct. There are two TDC's, one is an exhaust stroke. One is a compression stroke. Both will show the timing mark at about TDC. One will not fire, the other will. That would be the compression stroke. If a person sets the dizzy up to the exhaust stroke the rotor will be 180 degrees off. If they wire the plug wires wrong, timing will be off in any number of ways.

So this is simple. You figure out when no.1 cylinder is near or at top on the compression stroke. You will feel the force if you plug the hole with thumb or finger and see the mark is at or near TDC "1" mark. Then look at rotor.

If you are at TDC on the exhaust stroke you won't feel any pressure.
It's not super critical exactly where the pointer is. Should be at "1" or towards 10. It all depends on when a person stops turning motor when they feel pressure. You can then bring crankshaft around twice and stop at 5 BTDC, then look at rotor again.
It will fire and probably start if anywhere near. The fine timing later is to get it running good. Right now we just want to hear a few pops.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Fri Jan 29 2021 09:45 PM
The piston will come to TDC twice. Only one will be compression stroke. That’s why it is quite common for the inexperienced to get the engine 180* out of time. You want it on TDC during compression stroke only. Engines jumping time is quite common after a lot of miles. It usually happens when it’s running good and you shut it off. The rotating mass will cause the timing chain to skip a notch or two if it’s worn enough.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 09:55 PM
Usually if it's the chain, but not always, the carb or the tail pipe will backfire or spit or pop. This whole timing procedure above will not necessarily catch that problem. There will be a TDC and compression, and a rotor position. But that rotor position will not be synched to the piston anymore.
Just continue with the plan. Those motors are pretty bullet proof mechanically. Double roller chain.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:22 PM
[img]https://www.stovebolt.com/ubbthread...4157412-F921-47DF-9B38-345C3C445FBF.jpeg[/img]

Went and got remote starter button, pulled plug 1, stopped as soon as it blew my thumb off the hole. This is where it was, confirmed that rotor was pointing to my original #1 position, put wires back.

Still doesn’t start. But it does sound like it’s trying harder with wires back where they started. Video if you want.

Attached picture B4157412-F921-47DF-9B38-345C3C445FBF.jpeg
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:29 PM
Let's change the wording to "still does not fire". I don't want to get fooled by does not start. If there is no fire whatsoever, it is totally different than "won't start".

Been avoiding saying this BUT: I would not work on that motor until is is cleaned. IT IS WAY TOO DIRTY. The pointer is pretty far off from what I can't see. Maybe you can wipe off the timing disc at least.

Turn motor by hand twice around and stop at 5 deg BTDC. Show pointer pic and show pic or rotor.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:32 PM
It’s rust. Can I wire brush it, or steel wool? It definitely doesn’t ‘wipe off’.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:33 PM
YES but it's not rust. It's hard grime. Petrified dirt. You gotta use gas or carb cleaner or degreaser someday.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:39 PM
Ok. Will do. If you have any pointers for safely cleaning engine, I’m game.
Got to stop for today. I’m due somewhere at 5:00 and I’m dirty from crawling under truck for pics. I never did pull plugs to turn by hand because I got remote button, so next time I will clean timing disc, pull plugs and turn by hand as you said. May be tomorrow, may be Monday. Depends on what my gal has going for the weekend. Thanks again guys. I’m trying my best.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Jan 29 2021 10:40 PM
OK, later.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Jan 30 2021 01:14 AM
Martin, Jerry, et al, What do you think he should do next?
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Sat Jan 30 2021 01:44 AM
Check your PMs
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 07:46 PM
Back at it, cleaned timing disc, I can read all markings. Took plugs out, trying to turn by hand, not having much luck.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Feb 02 2021 07:50 PM
not much luck doing what?
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 07:50 PM
Turning engine by hand
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Feb 02 2021 07:51 PM
plugs out, trans in neutral, socket on crank nut CW
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 07:57 PM
Ok. I definitely do not have a socket that size, do you know the size off hand? I can grab one later on the way to work.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Feb 02 2021 08:01 PM
Don't know, find a bolt or nut that matches or measure or push some playdough on it and measure that.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 08:04 PM
7/8” is closest I’ve got, too small.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Feb 02 2021 08:05 PM
Good deal, we have reached 10 pages!
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 08:06 PM
Well today is done then. Work soon.
I’ll measure and get proper socket.
Posted By: bartamos Re: Ignition problems- 305E V6 - Tue Feb 02 2021 08:07 PM
10-4
Posted By: Phak1 Re: Ignition problems- 305E V6 - Tue Feb 02 2021 11:43 PM
Two things that stick out to me, and I agree Bartamos has been stellar:
  • the OP was asked to place his thumb over the number one spark plug hole to determine the compression stroke several times and that has not been done. This would accomplish two things you would find out if the timing is on the compression stroke and second you would find out if the timing chain has slipped. Once you know your on the compression stroke, look for the UDC mark and line it up to the pointer. Check where the distributor rotor is pointing to. To me this is the first thing that should be done
  • Hot Rod Lincoln asked to remove the fuel line from the carb and operate the starter and pump some gas in a container to see if the fuel pump is working and that has not been done.


One thing I would like go add is the possibility of water in the gas. I rebuilt the original carb then changed it twice on my 4-wheeler before I found that water was getting into the tank. Boy did I feel stupid!

I assume the 305 has a solenoid, and if it does, the OP could buy a remote starter switch and then would be able to perform these test himself. They are not much money and you can pick them up in most FLAPS. Heres one from Autozone. [LINK] [autozone.com]
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Wed Feb 03 2021 01:41 AM
FYI, the OP did purchase a remote switch.
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Feb 03 2021 03:02 AM
I did use the remote switch to get to compression stroke, and that is currently where timing disc and rotor are. Rotor is just past 1st plug and timing disc is a good bit past the UCD stamp, well above the dead center mark.(there is a photo link somewhere back there), I am going to try turning by hand tomorrow as Bartamos laid out, and I will report back.
I appreciate y'all.
-Jimmy
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Wed Feb 03 2021 03:09 AM
One more question. At one point I had a jumper going from battery+ to ignition coil+, and resistor wire, and hot wire from starter off of coil.
I put them back to run a test that was recommended here in the thread, to see what voltage the coil was getting at start.

If I do try and fire it up tomorrow, should I go back to jumper method?
(battery is fully charged, reading 13.19)
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Feb 03 2021 03:59 AM
You are not going to try and fire until the results and pictures of static timing procedure; and you may be rotating some more with plugs out after.

But yes you will be using the jumper. That is later after static timing procedure is done. If it's out of time because of chain or valve train, you would not want to try and start. You can damage the motor. Be patient. You may have to take valve covers off at some point.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 05 2021 06:42 PM
Jimmy and I have been working off line to keep the back and forth off of the post. The timing shows good. Stopped at 5 BTDC and rotor was on No. 1, went around twice again, rotor in same place. Hope the repeat means chain is OK. He has been doing really good for his first time with this stiff. I suspected that the weak/no spark was due to the way spark was tested. So now he has good spark. In case he has bad gas as was suggested, he is getting new gas and will squirt down carb. No throttle at all for now. We know carb has gas because he saw is squirting. Seems like no reason to test pump yet. Using a jumper for coil during these tests. Will report.
Posted By: 55shaker Re: Ignition problems- 305E V6 - Fri Feb 05 2021 09:59 PM
I've read all these posts, and thought that the both of you did a good job of communicating.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 05 2021 11:04 PM
I counted my incoming emails and sent emails and got 46. Plus 7 PM's. Plus 10 pics and several videos. Some may be embarrassing. Some are tough love. A lot was going over what was already gone over. We already had 10 pages on here. My last post is what happened just to verify spark was actually there. He goes to work fairly soon after we get going and emailing back and forth. That's no ones fault. Jimmy can post anything he wishes. He has compression, spark at, I think, the right time and is repeating, tried new gas down carb. No fire.
Starter is slow as far as I can tell from my house. He tells me over and over that battery is 12.6V or better. I told him that I've see starters show static 12.6V, be rechargeable but break down, It fools you. I don't want to explain the whole world of electrics, ohms law, specific gravity, hi and lo coil windings, pertronix.. to a guy who is new to this and wants the motor to start...... and i don't profess to know all that stuff either. I sensed, after a long time, that maybe he didn't know how to test a plug. He didn't. He had to buy a socket to turn the crank and so on. No big deal, but doesn't play well on here.

So I asked him to clean battery posts and clamps, starter and ground connections, to see if starter will speed up. Even though he says battery is new, take it to two places to get load tested. I told him if battery is breaking down, or starter is breaking down, that they will suck most of the available 12.6V and cause weak spark and/or weak spin. Testing with headlights on doesn't tell you if battery break down, starter breakdown, solenoid breakdown, cable or connection breakdown, ignition switch breakdown, ground breakdown.

I guess I saw a good spark from his non adjustable plugs (video) after we made some "spark plug testing procedure adjustments". So after clean cables, after battery load tests, then I guess we will attack and remove the starter. It does probably rotate enough for a good starting motor with good gas, hot spark, on a really hot day. It rotates about as slow as we have all seen on a battery going dead, but not dead yet. It's not a correct speed for a 6 cylinder, low compression motor with the plugs out. ALbeit very cold outside temps. If the starter is good, something is wrong inside motor or valve train.

Jimmy: Just thought of this!!! Check your oil ASAP to see any light color or milkyness. My grandson had water leak into crankcase and we broke the nose off of two starters before we checked the oil. Motor was locked pretty much. Whatcha call yer hydraulic lock. Just like this, we thought it was the starter. We said fudge and dang it after we found it.
Posted By: Phak1 Re: Ignition problems- 305E V6 - Sat Feb 06 2021 02:12 PM
Bartamos, has Jimmy actually performed a compression test? I looked thru the threads and could not see where that was done.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Feb 06 2021 07:40 PM
No not yet. Working with him now. Fresh gas down carb, no fire. Having him try full choke and pump, then no choke and no pump. Starter speed is iffy. He cleaned all cables. Trying with jumper from battery to coil pos. I can see gas surging in clear glass filter between pump and carb. I know he does not have compression gauge and no familiar with use. Hesitating, so far, to try and train and have him buy various one time items. Trying DIY methods. Getting to the end of my ideas. Not quite giving up yet.
Posted By: Sludgeburner Re: Ignition problems- 305E V6 - Sat Feb 06 2021 09:26 PM
Sounds like the coil resistance is wrong for the pertronix. When I installed my pertronix, I got the matching coil for it. The paperwork with the pertronix should tell you which coil to run. In my application the ballast resistor was taken out.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Feb 06 2021 09:37 PM
I saw a video of the spark. Don't know how to post a video. If it has spark it has spark. Had white spark. I just don't know what his kind of E3 three legged electrode spark should look like. Not used to that. Sun was shinning on plug when videoed. Seemed to jump to a different leg on each snap. He said he is running their recommended Flame Thrower coil.

1. Timing is right on, rotor returns to same spot several times, I assume that shows no timing train issues, don't know about valve train. Compression blows off thumb.
2. Gas squirt down carb test good, gas pulsing in clear glass filter located after pump, fresh gas dribble down carb, choke closed and open.
3. Plug sparks, with threads on clean metal, can't tell strength, looks good to me.
4. Jumper from batt to coil
5. Battery at 12.6V
6. Starter, semi weak spin rate, but seems enough to start. Not positive about that.
7. No discolor in oil.
8. It seems that all of the above covers the fuel, fire, compression and timing. But Obviously not. NOTHING has produced not one explosion.
9. Phil says compression. That sounds like a good idea. I haven't thought anything major was wrong but I do realize it's possible.
History is: took it around the block, started to stumble, died at home and won't even fire. Jerry say test test test, I think I have done that with Jimmy not having the equipment and knowledge. It's hard to do tests like Jerry can, with a far away member. I do the same tests without test tools. I guess I will suggest a compression tester. I think O'Reilly's loans them.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Sat Feb 06 2021 10:13 PM
I have seen instances of the cylinder walls getting washed down with too much gas or starting fluid in a no start situation and the engine doesn’t have enough compression to start. Just throwing it against the wall to see if it sticks.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Feb 10 2021 06:00 PM
Moved dizzy 1/8 CCW, no fire. Moved another 1/8, no fire. Used jumper cables. Starter still slowish. Trying to accomplish pressure test for each cylinder with a FLAPS loaner tester. Tester malfunctioned, release mechanism may be leaking. Brass release button fell off, can't find. May have dropped into a plug hole. Vacuuming thru plug holes to find..........
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Wed Feb 10 2021 06:12 PM
Wow!
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Feb 10 2021 06:14 PM
nanner nanner nanner nanner nanner chug I owe, I owe, so off to work I go

If you are not making mistakes, you are not doing anything.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 01:55 AM
and there it is.................. Jimmy bought a scope.

I think it's a boy.

Attached picture button.jpeg
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Fri Feb 12 2021 03:03 AM
Too bad it’s brass, some of the scopes have magnets on the end.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 03:09 AM
Yes, that was the first thing I thought of, magnet on a piece of plastic tubing. Pistons are aluminum so would have worked. I sure hope the first test was bogus because of a screwed up tester release valve.

1 = 70psi

3= 60psi

5= 85psi

2= 0 (button found here) (spring for button found in cobweb somewhere)

4= 0

6= 0

Going to rig up 1/4 ID tubing to the shop vac and get it to "stick" to the suction. The piston got stuck during trying to get to TDC. If it was the exhaust stroke it hampered the first shop vac effort before we know if and where it was. Tried to bring piston near top to create a small chamber. The chamber would have not pulled a good vacuum if valve open. Does not matter now we know it's in there and where, no need to pull a vac on whole chamber. Probably better to let piston down now for better visual and straighter attack angle for hose/tube.
Posted By: KEVINSKI Re: Ignition problems- 305E V6 - Fri Feb 12 2021 03:14 AM
Maybe one of theses they are a handy tool and cheep

Attached picture 7168ED3F-C133-4CDB-B191-181CCD4E2531.png
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 03:22 AM
Not bad but a more blind approach and would need to be exact. The hose can wave around like a magnet and catch it. If it appears below the hole, the grabber may be good. But the piston top is not perpendicular to the hole centerline as far as I know. That is a good thing for the tube because button will be on the gravity down side.
I'm asking him to push button down against bore wall to trap it for the suction tube. Also asking of suction tube can be attached to scope head, sticking out a little so as to see it, and guide it right to the button. Hole probably not big enough for that. Maybe stick hose in after scope head goes in and then visually guide it to button.

This motor is looking for 125 PSI +
10% variation OK. Maybe.
Consistency, as we all know, is important. It's a dry motor right now and it can't be brought up to temp either.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 07:09 PM
Got it with the tube. Heavy snow coming.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Fri Feb 12 2021 08:15 PM
thumbs_up Don’t you just love it when a plan comes together!
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 08:21 PM
Yes, but the real plan has not come together yet. Very glad to get that button out. Jimmy is a trooper. Tried to retest, got a zero reading and taking gauge back. I myself have never heard of a zero so I said it has to be a bad gauge. That would be a mighty big hole. The initial goofy test showed bad PSI all over. I guess, if true, that means valve train/chain all screwed up. I don't believe it yet.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Fri Feb 12 2021 09:12 PM
Just asking, not criticizing, does he know how to do a proper compression test? Three cylinders very low and 3 at zero = very suspicious readings. Borrow a better tester and try again.
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 12 2021 10:22 PM
We have gone over test: throttle open, choke open, plugs out, 6-8 compression strokes for each cylinder. Watch for gauge needle to stop moving. He is getting a different gauge set. Weather may delay the test. I have gotten his permission to update the post. I'm close to a dead end depending on the compression test. I will, or Jimmy will, ask members more experienced than me on compression failure procedures to help. If the test shows good pressures, I am probably still at a dead end and have missed something myself. Sadly. We will see.

Martin, your or anyone else's help, questions and positive support is appreciated. There is no offence at all taken. thanks
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Feb 24 2021 08:26 PM
New compression gauge, new numbers. Throttle and choke open.
1 = 20
3 = 70
5 = 80
2 = 82
4 = 70 once, second time 0
6 = 0

Is this 100% timing chain/gear broken???????? or what else to check???????????
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Wed Feb 24 2021 08:34 PM
As I mentioned long ago, I vote timing chain. Driving one minute shut it off won’t start. Classic timing chain. We’ll see. Thanks for the update.
Posted By: glenns towing Re: Ignition problems- 305E V6 - Wed Feb 24 2021 10:22 PM
Wow that took awhile. Definitely sounds like its out. I think i saw a timing chain on here somewhere for sale.
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Feb 24 2021 10:32 PM
With 60,000 original miles on a bullet proof motor with known reliability, it was not on my mind. Can't believe it really. I will have him take off valve covers and take a look. Just is case all heck broke loose up there. That's a long shot but has to be checked before teardown. If he does not have a double chain I will have him convert. Any other ideas before teardown????

One family truck, all they did was use it for camping.
Posted By: drdoug Re: Ignition problems- 305E V6 - Thu Feb 25 2021 01:40 AM
Could it be as "simple" as stuck valves? E10 loosened years of crud and the valves stuck in their guides? I don't know the GMC V-6s enough to know if there is a valve-piston interference problem, but I'd be thinking stuck valves before a broken timing chain.

An anecdote - I tore down a "runs good" 454 years ago that had shed the nylon portions of the timing sprocket. Even with that, the chain was very loose, but still caught on the remainder of the aluminum sprocket, and hadn't jumped time. Of course the nylon nibs that migrated into the crankshaft oil passages (filter must have clogged and bypassed) didn't do bearing lube any favors. The crank was salvageable, but had to be ground (fortunately it was standard dimension). I know the GMC isn't a big block Chevy, but I'm thinking the GMC is pretty robust.

Tear the engine down, and see what's going on. My two cents

Doug
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Feb 25 2021 08:00 PM
Don't think all the valves would be stuck.
Posted By: drdoug Re: Ignition problems- 305E V6 - Thu Feb 25 2021 10:20 PM
Bart/Amos - I was only throwing out a suggestion, since I hadn't seen it mentioned in this thread. IMO, it would only take 3 of 12 really stuck to give those readings like that on a cold, dry, possibly tired engine. Or are those numbers for a "wet" test?

But my main point was, it's time consider a systematic disassembly and inspection, and the top end is easiest to get to, so why not start with making sure the valves are free (and move with engine rotation, as I think was mentioned earlier)? If possible, a leakdown test might be a better starting point, but it's likely to show all cylinders leaking at the valves from what you describe and have been working with the OP, so the V/Cs need to come off, anyway.

Again, just my two cents. Cheers!

Doug
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Feb 25 2021 10:40 PM
It's Bartamos not Bart/Amos

Didn't know readings like that can only be a few valves. Not very knowledgeable on that. Some of the things mentioned may not be feasible for some owners to do. I have asked him two days ago to take off valve covers and when his business schedule permits, he will. I can't assess or train what to look for over the internet. Tearing down in his driveway scares me. I believe I'm just going to say a general statement that it seems like timing chain or other associated parts. Not recommend a DIY or go to a shop or get a Chevy motor. I will answer any questions after that and stop trying to find and fix. I will recommend returning to Stovebolt with a new post and explaining the problem and history of tests. I am not qualified to help with a teardown over the internet. If I was doing it I would take off bumper, grill, radiator, radiator crossmember and etc. to sit in a chair and pull all the stuff off the front of this Big Block 305 V6 monster. But not out front in my driveway, which is where it is stuck. I've had several of these motors. Solid lifters.
If the rockers are in tact, springs in tact, everything going up and down OK with motor cranking, then unfortunately it's Kings X for Jimmy. Painful as it is, a decision will be made on how to continue..........

Can someone tell me if a blown head gasket can give these numbers??????????

Would it do any good to squirt a little oil down each cylinder in case ALL the rings are stuck or not sealing? Again it seems like all cylinders can only exhibit low numbers due to chain or gear failure. The thing that puzzles me is we check timing regarding no. 1 compression stroke and rotor position. We rotated around twice to see if rotor returned, it did. Although I was not there, it seemed he did it correctly. Yet it won't fire once. Has spark, has gas, seems timed but no compression. Does that point to head gasket??????????? Can all cylinders be "washed"???????
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Thu Feb 25 2021 11:38 PM
Just going to toss this out there. In my neck of the woods there are lots of “Mobil Mechanics”, some even ASE certified, who will come to your home and check the engine out. I don’t know what the OPs financial position is, but it might be worth a few bucks to get some professional help. I would be wary of one that doesn’t have grey hair. An hour or so of the mechanics time is going to accomplish one of two things. #1, hopefully the engine will be setting there purring like only a 305 V6 can do, or the OP will know to start saving up for a complete overhaul. Just a different way to proceed.
Posted By: bartamos Re: Ignition problems- 305E V6 - Thu Feb 25 2021 11:44 PM
Not a bad idea at all. Gets me off the hook too smile
Posted By: Xena Re: Ignition problems- 305E V6 - Fri Feb 26 2021 08:15 PM
Old engine with solid lifters being driven shortly after getting it started without running it back in without revving it and checking for proper lubrication after years of sitting is never a good idea. If you are lucky, you will be able to get away with just new pushrods (to replace the bent ones), lifters, maybe a few rocker arms, maybe a cam, possibly a replaced valve or two and a timing chain. the lifters in the block could be stuck, the valves in the head could be stuck and bent. Unlike hydraulic lifters, solid lifters are unfogiving. Any of those components jamming will cause and old timing chain to jump time.
Posted By: BC59 Re: Ignition problems- 305E V6 - Fri Feb 26 2021 08:35 PM
Originally Posted by Justhorsenround
it might be worth a few bucks to get some professional help. I would be wary of one that doesn’t have grey hair.

I look at it for free if it was local. Got all the qualifications!
Posted By: Xena Re: Ignition problems- 305E V6 - Fri Feb 26 2021 08:53 PM
FYI: I worked for Chevrolet as a dealership flat rate mechanic for 25 years rebuilding engines, and I am 66 years old and don't have grey hair.
Posted By: TerenceandMary Re: Ignition problems- 305E V6 - Fri Feb 26 2021 09:17 PM
Not sure if it will apply to this particular motor, but if you're trying to get a look inside without tearing things down to far I have had success renting a flexible inspection scope. Some have a light built in and some don't, if you don't have a light on the end of it it makes things harder (trying to juggle and aim a really bright flashlight down the spark plug hole is no fun). I would think that if it were a head gasket there would be some oil dribble from the head or heads, unless the motor was super dry on the top end (or already covered in oil to the point where you can't tell if it is leaking). using a flexible inspection scope and very slowly turning the motor by hand (if it still spins) should help to get an idea of what's going on. It helped me find a broken rod on a dormant Benz motor years ago, was better to find it that way than to try to start up without knowing.
Posted By: BC59 Re: Ignition problems- 305E V6 - Fri Feb 26 2021 10:26 PM
Originally Posted by Xena
FYI: I worked for Chevrolet as a dealership flat rate mechanic for 25 years rebuilding engines, and I am 66 years old and don't have grey hair.

Doing better than me, been with G.M dealers since 1980, I'm 61.5 & have lot of grey hair, happy to have hair!
Posted By: bartamos Re: Ignition problems- 305E V6 - Fri Feb 26 2021 11:00 PM
Here is the problem in my little mind. Don't want to recommend tear down of timing chain. Don't want to recommend taking heads off. Don't want to go after the wrong thing.
Keeping in mind that ALL cylinders are low:

1. If it was head gasket, it's a V6, it has two head gaskets. Both blown?
2. If it's timing chain/gear, why did rotor return to point right at no. 1 after rotating motor 360 several times? That seems to indicate no slippage and at least no. 1 would have compression.
3. I don't know if this motor is an interference motor or not. If not, there are no bent valves.
4. I guess if all pistons/rings were stuck or cylinders washed dry, that would be no compression and I guess not even one cylinder would fire?
5. It does have spark, it does have gas, if the test were done correctly by poster.
6. A leak down would be good to do.
7. He does have a scope. All you could see is piston top and walls. I hope they are going up and down. A straw in each hole will tell you that.
8. The 1, 3, 5 bank is not a whole lot different than the 2, 4, 6 bank.

Going to add two good squirts of oil into each cylinder and see what that does for compression. Trying to be sure with limited tools and limited experience and over the internet, before recommending DIY tear down or mechanic services. If a miracle happens and cylinders come up to 125, that will be nice. If not my guess has to be the Martin opinion......timing chain. Should not be that with 60,000 miles. Double roller chain very strong, No stretch in 60K miles. Big strong forged steel gears, But............ the bad thing is I know I'm wrong somewhere.
Going to also repeat the rotor test again now that motor has been cranked a lot. Bring no.1 up to TDC on compression, look at pointer, look at rotor pointing at No. 1 . Then rotate motor 360 and look at pointer and rotor again.
Posted By: glenns towing Re: Ignition problems- 305E V6 - Sat Feb 27 2021 12:34 AM
Pull da cap. Look at da rotor. Turn crank in 1 direction till rotor turns. Then turn in da crank in other direction and sèe how far, or degrees it takes to turn rotor. That will at least tell ya if da timing chain is a sloppy mess. Stretched, gear stripped, or other timing issue? Im not convinced that #1 compression stroke is being verified and-or rotor is pointing at #1 when it supposed to. Theres no way this truck went from good running to inoperable in a flash w/o a mechanical failure if all other necessary components are in place.... Fuel, Spark, ..... the other 2 are Timing and Compression that seem to be questionable?? Unless of course da cylinders are washed down?? Then oil squirting will verify that. Unfortunately like previously stated, maybe da kid needs a better hands on, knowledgeable helper? JMO
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Feb 27 2021 03:11 AM
He's not a kid. He's 49. Got confirmation pictures of the pointer and rotor.
Posted By: Xena Re: Ignition problems- 305E V6 - Sat Feb 27 2021 05:52 AM
So I have reread through the entire 14 pages of this thread and am impressed at the effort made by Bartamos in particular and others in trying to solve Jimmys issue. One thing that I missed on the first read was the latest compression test results. Cylinder #6 had a reading of 70 and then 0 during a subsequent test. I don't recall any mention about oil pressure PSI or the removal of the valve covers to see if the top end (much less the rest of the engine)is being properly lubricated. A reading of 70 PSI and then 0 would indicate to me that a component is sticking for a low reading of 70, or a reading of 0 indicating (to me at least) either a stuck lifter in the block bore or inadequate lubrication of the rocker shaft (which would affect the travel of all the rocker arms), or both, resulting in at least some if not all,valves not closing or opening effectively causing low compression readings. I would also suspect possible cam lobe damage as well. To state the obvious, head gaskets and timing chains are not going to momentarily repair themselves and then fail. Also, metal components, as we all know, expand when they heat up and contract when they cool.

I am more convinced than ever, based on what I have read, that the issue is lubricant related. If it were my engine, I would first remove the valve covers and assess how much fresh oil is visible on the rocker arm shaft, rocker arms and head in general ( it will also provide a good general assessment of the lubrication of the engine parts not visible). If lubrication is fresh and obviously sufficient, I would then assess the condition of the pushrods (at piston TDC you should be able to spin them with your fingers); if they look to be unbent I would proceed to turn the engine over BY HAND (wrench on crankshaft) and assess the rocker arm and valve travel. If all rockers and valves seem to be moving freely, I would then adjust all the valves, one cylinder at a time, and then do another compression test. Compression test readings are always going to be low if the engine has not been warmed up; as in this situation that is not possible, look for consistently close readings between cylinders (10 to 20 PSI would be optimal). Using a oil can to spray oil into the cylinder top and wall gap with oil before testing will temporarily help seal the ring / bore gap and raise the PSI reading. Two adjacent cylinders having a low reading in contrast to normal readings in the other cylinders often indicates a 1 blown head gasket, 2 a cracked cylinder wall between the cylinders, and 3 a cracked head; all three are most often a result of overheating the engine.

Having done all that and everything looks good, I would imagine it would come back around to timing and ignition settings. Below I have provided some valve and ignition info that hopefully will help get it going, from the Service trade Edition of Motor Truck and Diesel Repair Manual 28th Edition:

1966 GM 305-E V-6 engine:
Spark Plug 45ns Plug GAP .035
Distributor Point Gap .019 Timing Mark 5 degrees Firing Order 1-6-5-4-3-2
Valve Lash Intake .012 HOT Exhaust .018 HOT ( Cold, I would look for intake .015 to .017 and exhaust .021 to .024 and plan on readjusting them once the engine is running and hot ). Valve spring pressure (LBS @ inch length) 200 @1 1/2
Compression Pressure at cranking Speed 135 PSI

Valve Adjustment Procedure (verbatim from manual): With engine at operating temperature and rocker arm covers removed, turn adjusting nut on each rocker arm until proper clearance is obtained between valve stem and rocker arm.
Best of luck
Posted By: TerenceandMary Re: Ignition problems- 305E V6 - Sat Feb 27 2021 06:58 PM
with 4&6 reading so low I would hope for a head gasket or a cracked head on that side, maybe even some head warping from excessive heat. I had seen it happen a bit out here where it gets so hot. occasionally improper torquing of the head bolts could lead to something like that, though this looks worse that any case of that happening that I've seen before. another wet compression test with fairly consistent results may help pin it down.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Feb 27 2021 11:53 PM
Good info guys.
I don't believe the cranking of motor with a slightly slow speed starter or weak battery would produce enough oil pressure to reach rocker area. We will be inspecting that. Next test is oiled cylinders.

Will take off covers and spin push rods by hand, check rockers, springs, and watch overall operation and oil flow during crank speed.

The hand crank pointer/rotor test will be repeated. We will reverse direction, as suggested, to observe slop.

It would be nice if we detect faster speed crank after oiling cylinders by hand. It would be nice to see at least 4 cylinders go to 100+ psi.

Next opportunity for OP is Mon-Tues

I have just asked him if he ever changed oil. If he has a cartridge oil filter or spin on. If he changed cartridge.

EDIT: Oil not change for a long long time. Filter not changed. Unknown if that's 33 years or not. A sitting motor will form condensation during weather cycles and have dripping water inside valve covers and crankcase. This can turn into a living environment for "swamp thing". May not pump thru unchanged filter and into motor....or may pump some sort of unknown chemically altered fluid into motor and "stick" it up and dry it up. In addition, may have allowed washing during the test drives. A series of eventual loss of compression.
I want to hand flush all of the valve train and let it drain into pan, then drain pan. Change filter, add 5 qts thin oil by pouring over valve train and do the oil squirt compression test. What should top of motor be hand flushed with? Gas, Mystery oil, kerosene...... keeping in mind is will be drained out. Don't want it to circulate anyway.
Don't want to add more bad 33 year old oil to the situation. Just trying to give the oil-in-cylinder compression test the best chance, as this may be the last chance, before teardown.
My fantasy is we get enough compression to start, oil circulates and fees up motor, then change oil a few times and "whalla", it's fixed. aye? No damage. I am hanging on to that it has spark, is timed and getting gas.

One of us is gummed up and washed out........me or the motor.
Posted By: Xena Re: Ignition problems- 305E V6 - Sun Feb 28 2021 05:22 AM
Based on what you have described, a teardown, thorough cleaning and evaluation of the internal components is the only truly reliable solution. The possibly 33 year old oil has, in all likelihood, solidified enough sludge in the bottom of the oil pan to at least partially clog the oil pump pickup screen and possibly the oil pump itself. The oil that is still liquid has been mixed with condensed water and has been circulated (however weakly) through the engine so the crank, rod and cam bearings will need replacing. The cylinder walls, at the very least, will need to be honed, and may need to be bored out. The piston rings will need replacing if honed and the pistons and rings if the cylinders are bored out. The rods and wrist pins should be evaluated. The lifters will need replacing and their block bores honed, and replacing the cam would be a good idea. New oil pump. All engine block oil passages, after removing the threaded pugs at their ends, need to be cleaned out with a gun cleaning rod with a copper or brass brush (my personal choice is .22 caliber). All freeze plugs should be replaced.The crank will have to be evaluated, including measurement, to see if it is reusable. The oil return passages in the heads will have to be cleared. By rights the stripped block should be hot tanked at a local machine shop and checked for any cracks that may not be visible to the naked eye. No mention has been made about the cooling system, but if the oil is that old, chances are the 33 year old coolant lost its effectiveness long ago and may have frozen in the block at some point, cracking it. Those cracks will widen as the engine warms and mix more contamination into the oil from coolant passages as well as possibly causing low compression and / or hydro-locking of the cylinders after the engine is shut off.

The cleaning process with such old oil and solidified sludge is not just a matter of clearing passages, but also insuring that there isn't any sludge left in recesses that are not easily visible. The new oil in a newly rebuilt engine (or any engine for that matter) can soften old sludge to the point that it will break away from the surface it was adhered to and travel through the engine, contaminating the new oil on the way and possibly causing new blockages depending on where it gets caught in the engine.

I really don't want to be the bearer of bad news, but in my opinion, any attempt of a less thorough repair at this point is a roll of the dice. Even if it were to run, however poorly, it won't be reliable and at some point, not so very far in the future, will fail, and in all likelihood will not be repairable.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sun Feb 28 2021 05:56 AM
The motor is absolutely not worth it. Tearing down for the experience, or to try and identify the issue, would be entertaining. A good running 305 V6 can be had for $200-$500. They are a 100% boat anchor for "performance" and max out at about 3400 rpm. Good torque, well built. If I had this situation and I would buy another or drop in a SBC or BBC. The motor is just rare enough, and has a following, to where the parts are worth money. Pistons, rings, some of the valve train, gears, timing chain, and other parts are either expensive or a bit hard to find for a rebuild. The nostalgia factor of being his Dad's truck, bought new, may have an effect. This is why I'm trying so hard, and seem so silly, to find a way to get it going without teardown. I do realize everyone is probably right and a teardown is already past due. I will report back in a week or two. I am familiar with these motors and they are an engineering marvel. They have a very very strong oiling and water circulation design. Very strong metallurgy. Could withstand the lack of oil and washing.

Motor designed for 200,000 miles back in 1959 after GMC told to cease and desist in selling trucks with Pontiac V8's with a GMC sticker on valve covers.

First GMC V6:
HIGH OUTPUT OIL PUMP:
capable of pumping 14 gallons of oil per minute, provides extra circulation at all engine speeds
. . . extra protection and well oiled surfaces on all vital moving parts. Engine is lubricated as
soon as it's started. Cam lobes dip into a built-in reservoir of oil as the camshaft rotates,
preventing cam and valve scuffing - a major reason why this engine gives long, dependable service.

135 GALLONS OF WATER:
(at 3400 r.p.m.) Are pumped through this engine every minute. With thermostat open, only half the
water goes to the radiator, the other half returns to the pump through a by-pass. This results in
excellent cooling ability. There is less than four degrees variation in water temperature throughout
the engine. This checks the possibility of hot spots. Here's cooling efficiency that is not matched
by any other comparable size engine. Life of pistons, valves, valve guides and spark plugs in much
greater, and the possibility of head-cracking is held safely in check . . . further proof of the
durability and long life that is built into this engine.

FULLY-MATCHED COMBUSTION CHAMBERS Smooth, precision-machined combustion
chamber minimizes carbon deposits, hot spots & pre-ignition. & there is uniform combustion in all 6
cylinders for smoothest engine operation. 6 equally-spaced head bolts surround each cylinder to reduce
bore distortion, & guarantee gasket sealing for long engine service.

RELIABLE TIMING LINKAGE V-6 roller timing chains are double-strand, for
double durability.

FREE-BREATHING INTAKE VALVES Forged from steels with high resistance to warping,
pitting, & wear, extra-large intake valves let the V-6 breath freely, for higher volumetric efficiency.

FREE-VENTING EXHAUST VALVES Compared with other engines of equal displacement,
V-6's have the largest exhaust valves of all -- to keep back pressure low, efficiency high.

HARD FACES & INSERTS Tough, Silchrome XB-steel exhaust valves, hard-faced
with Ni-Chrome

Spark plugs are on the inside at top of motor away from exhaust manifolds. Long reach plugs provide greater heat sinking. Plug wires stay on top of motor.

"SCUFFPROOFING"DIP Before pressure lubrication takes over on engine starts,
V-6 cam lobes dip into a special oil reservoir. No "dry scuffing" mare cam or valve-lifter faces!

POSITIVE VALVE ROTATION A positive ratchet action rotates every valve on each cycle.
Contact surfaces stay clean for positive seating. Standard, 305C & up

M400 CONNECTING ROD BEARINGS Big, long-life M400 bearings are used in V-6
connecting rods. Low-friction tin & aluminum alloys are backed with a layer of steel for extra strength.

EXTRA-LARGE MAIN BEARINGS Huge, M400 main bearings provide solid support for
the crankshaft, & resist wear by spreading the load over extra square inches of bearing area.

PRECISION-FITTED PISTONS In every V-6 the big, deep-skirt aluminum pistons are
weight-matched, & precision-fitted to the bores, a cast-in steel band controls heat expansion.

SHORT, RIGID CAMSHAFT Extra-wide camshaft lobes are flame hardened & phosphate
coated to resist wear. Four big bearings carry the shaft for precise valve operation.


RUGGED CONNECTING RODS Piston power flows smoothly to the crankshaft through
big, forged-steel, I-beam connecting rods -- all balanced to within the weight of a cigarette!

SHORT, STIFF CRANKSHAFT This husky crankshaft helps conserve engine power &
extends bearing life, because it has the strength & balance to minimize deflection & vibration.

RIGID, RUGGED BLOCK This block has strength to spare for resisting internal strain --
strength from it's super-tough iron alloy, staggered cylinders & short, deep-skirt design.

M400 is Monel. 80,000-90,000 PSI tensile. High corrosion resistance.

How's this for a demonstration? Spinning motor from the rear.

Attached picture BBV6.jpg
Posted By: glenns towing Re: Ignition problems- 305E V6 - Sun Feb 28 2021 03:30 PM
Nice write up. Makes it sound great to say da least. I like em alot. Hope he gets it going. When i said "kid" i was using da term loosely. Not any disrespect intended.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sun Feb 28 2021 09:17 PM
thumbs_up
Posted By: bartamos Re: Ignition problems- 305E V6 - Mon Mar 22 2021 11:11 PM
Looks like she may have slipped timing. I really think that is the best of all evils. The fix is cumbersome with big heavy casting to remove but it's all in front and does not disturb any complicated components or head. A mechanic came over and they say that the rotor does not return to No. 1 every time. Like we thought we thought it did. He is coming back to check again and do a compression test.
Since it's hard for me to believe a low mileage 305 V6 has a stretched chain or broken gear, I guess it can be bad dizzy gear.
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Mon Mar 22 2021 11:28 PM
thumbs_up
Posted By: Jimmy66 Re: Ignition problems- 305E V6 - Sat Apr 10 2021 04:52 AM
Hey everyone- I wanted to let y’all know, I towed the truck to a reputable local shop that specializes in older vehicles, and restorations.
I told them the whole story, and the owner had a hunch. He pulled the valve covers and we found bent push rods, some disconnected. Only one cylinder with a straight rod and compression.

It appears that when I got the truck running, and drove it for a couple days, I stirred up the separated gas sediment in the bottom of the tank, which acted like glue and locked things up. That was last September, and I’ve been chasing my tail since then.
Huge thanks to Bartamos for going above and beyond to help me, and thanks to all of you for help and insights. The truck will be fixed, and I will continue to learn.
Thanks y’all- Jimmy
Posted By: Phak1 Re: Ignition problems- 305E V6 - Sat Apr 10 2021 12:37 PM
Originally Posted by Jimmy66
Huge thanks to Bartamos for going above and beyond to help me, and thanks to all of you for help and insights. The truck will be fixed, and I will continue to learn.
Thanks y’all- Jimmy

Glad to hear you found the problem and your going to fix it! nanner

Bartamos, did you send Jimmy the bill for your opinions? @ .02 cents x 62 opinions = $1.24 as I see it. LOL!
Posted By: Justhorsenround Re: Ignition problems- 305E V6 - Sat Apr 10 2021 12:39 PM
Thanks for the update. Unfortunately you found the common problem with trying to start a long dormant engine. Our Tech Tip covers the proper procedure but hindsight is always 20/20. Good to hear she will live to run another day.
Posted By: bartamos Re: Ignition problems- 305E V6 - Sat Apr 10 2021 06:35 PM
Didn't charge this time. Putting up with me is priceless smile

I am really puzzled by the shop saying it was old gas "gluing" motor together and bending and breaking valves. I know motors can be locked up/frozen and need a procedure to "loosen". A first start procedure. But this was presented as driven around the block and parked, then won't start. A mechanic knows more that I, but I'm going with timing gear/chain or dizzy gear sent motor into chaos. There is at least one strike against my idea, the motor is a "clearance motor" so piston supposedly would not hit valves. He first had a mobile mechanic say timing was indeed off. I was advising taking valve cover off after one more test, but I backed off when mechanic arrived. Then it was taken to a shop. These were good decisions on Jimmy's part. Mechanic is going to find out that parts are not easy to find I suspect. I'm going to suggest to Jimmy that these motors are available for $200-$500 running. A rebuild can be 1000's from a shop.
Posted By: Xena Re: Ignition problems- 305E V6 - Sun Apr 11 2021 07:21 PM
Exactly the diagnosis I made on February 26, and wrote up in great detail on Feb. 28.....little or no lubrication leading to internal damage
Posted By: bartamos Re: Ignition problems- 305E V6 - Wed Apr 21 2021 02:01 AM
You da man.
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