The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Ignition problems- 305E V6

Ha! Just saw last post. Very PUNNY!

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.

battery was 12.34 today. it definitely has gas, not all that old.

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.

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.

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.

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.

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.

Will do. I should have some time tomorrow to do all of the above.
have a good night.

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

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.

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.

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.

May be we better wait for better weather. taking too long.

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.

It fluctuated around 10.7-11. I have video of meter while I’m cranking if you want me to send it.

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)

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

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.

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.

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

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.

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?

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.

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.

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?

I mean crank is currently just past UDC

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.

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?

I’ll mark wires for which plug beforehand.

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.

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.

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.

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.

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.

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.

[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.

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.

It’s rust. Can I wire brush it, or steel wool? It definitely doesn’t ‘wipe off’.

YES but it's not rust. It's hard grime. Petrified dirt. You gotta use gas or carb cleaner or degreaser someday.