The Stovebolt Site Forums The Shop Area Engine Shop Timing and Starting

So I have replaced all of the ignition components, distributer cab, rotor, points, condenser, resistor, ect. and it sill wont start. I've got plenty of gas going through the carb as it it leaking but my spark plugs are dry to the bone... why is this? also i set the timing to TDC and started to turn the truck over, it sounded like it was about to catch and fire up but instead just coughed out of my carb and went to a really slow turn over... Could this be from when i set the trucks timing to TDC on the Camshaft the Crank was at the wrong spot, opening the exhaust when it should be intake?

Assuming 53 gmc with 228.

Pull battery cables off
remove number 1 spark plug (front of engine)
Place your finger over the number 1 spark plug hole, and crank the engine by hand. When your finger is blown off the hole, you will be close to top dead center for cylinder 1.
Continue cranking the engine by hand untill the bb is visible on the bellhousing timing pointer. This should get you close enough to start the engine.
remove distributor cap and examine where the rotor is pointing.
This will be the location of your number 1 spark plug wire. Move the distributor body to line the rotor up with a spark plug lead that makes sence (I try to line number 1 up with one of the hold down clips)

wire plugs in firing sequence...1*5*3*6*2*4 clockwise
replace the battery cable
squirt some fresh gas directly down the carb
turn ignition on and crank engine

Did your engine start?

It sounds like you did exactly what I did. I had mine 180 degrees out of time. It coughed, sputtered and backfired through the carburator. Swingdaddy has the right plan.

Okay, so me and my dad did what Bigdaddy told us... still nothing, i am stumped out of my mind... i mean ive replaced all the ignition parts, plugs, wires, ect. it just doesnt make since

BTW yes it is a 228, is there any body that could post a step-by-step video or pics as to how to properly time the engine? also on the distributor cap, does it matter where (in the cap) the number one spark plug should be? my auto teacher says theres usually a dedicated "post" for it... but i have no idea

If you look at an original diagram it will show you the position of the #1 tower. As far as working, as long as you have the engine on #1 and on the compression stroke and have the proper firing order for the rest of the wires the truck will run. Don

Well I have a slightly different take on the timing. Assuming that the 228 is similar to the 216 in this aspect, you will have a small ball on the flywheel and about five degrees from there, a triangle with the words UDC. I would suggest setting it so the points begin to open at UDC.

If it sounds like it is trying to start, try varying the timing by small increments. Too much advance will make it slow down or stop dead. When you get it right it will speed up as it is trying to start. I would say that you will want full choke on too.

Hi Josh,

OK, The info below is from Hotrod Lincoln (jerry), who has helped me several time on the timing issue. Maybe he'll chime in here, but this is his step by step method.


Pull the valve cover, and watch the #6 cylinder rocker arms.
Turn the engine over slowly by hand until the exhaust valve is almost closed and the intake valve is just beginning to open.
The #1 piston will be at top dead center, or very close to it.
Turn the distributor housing clockwise until the points close, then turn it counterclockwise until they barely break open.
You can find that point by touching the distributor side connector at the coil with a test light with the ignition switch turned on.
Turn the dizzy clockwise until the light goes out, then back it up until the light comes on.
You'll be "static timed" close enough to start and run.


This way you can check when the ignition fires, regardless of flywheel marks.

So heres an update, i took the valve cover off and waited until the first intake exhaust were up. As my auto teacher instructed that that would be TDC. since doing that i rewired the distributor cap the now correct way for the plugs, 1-5-3-6-2-4, clockwise. Yet again no fire, i will add a link to show pics of the engine now that it is cleaned up and all my new parts are on. but i am still stumped as to why it wont start, everybody i have gone to says its the timing... well if its at TDC now, shouldn't it start????

www.flickr.com/photos/62172307@N06/

With #1 TDC, both the intake and exhaust valves (for #1) would be up (with both rocker arms loose).

Do you have anyone who might be able to help that has done this before? Sometimes there's more to it than just replacing parts and following the instructions word for word. A little understanding and experience might be just what you need to borrow, and next time you can be that guy and help someone else with their project.
It's difficult for all of us out here miles and miles away in front of a computer to see what's going on and tell you what to do next other than the basic stuff we've already covered.
I'd be glad to help if I were closer, but it's a substantial drive to get there..

Grigg

If you are sure you have fire and gas to cylinders and have timing approximately correct loosen vacuum advance clamp. Have someone crank while you sloooooooooowly advance and retard distributor you should be able to hit optimum start spot fairly quickly. I found loosening the vacuum advance clamp allows you to more gently move distributor without fighting vacuum line

Are you absolutely sure you have fire to plugs? Let engine set awhile to clear any chance of flooding then try it. I use starting fluid in small doses but others may recommend against this.

@Grigg, I have my Dad helping me, my uncle over the phone and my shop teacher at school, and anybody on here who's suggested anything.
@kb3csw, im pretty sure i have fuel and fire to the plugs, but to be certain how to i check? and when you say have someone crank, do you mean by hand or actually turning the engine over?

FYI i have noticed when I am turning the engine over there is a really stiff spot.... could i possibly have a stuck/sticking cylinder?

You could have a one or more valves stuck, if that is the case the affected pushrods may bend. If you have a valve stuck closed it will effect compression and intake and expelling of fuel air mix. Since the motor is turning it is unlikely you have a stuck cylinder as that would lock everything. By cranking motor I do mean have someone turning motor with starter and electric on to ignition system.
You say you have fire with spark plug removed from hole and grounded against block can you see a spark jump the gap when cranking?Alternate method is to stick your finger in spark plug wire boot against the metal have someone crank with intuition on if it bites you have fire, I personally don't like this as well as I did when I was twelve. Since you are cranking without it starting you should see some evidence or smell of gas if you remove spark plug and sniff it. Is your battery in good shape and able to hold a charge?
To determine if you have a stuck valve you can remove rocker arm cover and crank engine by hand or starter as engine cranks you should see some movement from all valves this does entail some risk as you could further bend pushrods but likely if they are going to bend they would have already done so. A safer though somewhat more complicated way would be to remove rocker arm assembly and individually tap on each valve stem to see if they move.
Stuck valves can cause backfire thru carburetor as well.

Found your other thread in tons of fun, appears you have determined you have spark. Check valves to be sure all are moving. 180 degrees out of timie will cause backfire thru carb and coughing as well. Found that to be the problem with my 54 PO had apparently worked on it prior to my acquiring it and I replaced points etc and tried starting it with no success using his settings finally in desperation changed all wires 180 and it fired up.

So i just realized something huge... when i first tested for spark there was none coming off of the engine block, but there was off of the frame so we went with that. I just realized my engine is not grounded so that means there is no spark inside my cylinders.... any suggestion as to where i should ground the strap to? it is currently grounded off of the starter

If your starter motor works then the engine is grounded already....

Grigg

OK,

Sounds like you have spark...
Do you have fuel? Above I gave you a breakdown, and instructed you to poor some fresh gas down the throat of the carburetor. Did you try pooring a small amount of gas down the carb?

If you have spark and fuel, and your engine still won't start... A compression test is in order. Several people above have hinted at reasons why there might not be compression, including stuck valves.

The gmc 6 cylinders are solid motors, and are known to run even with 3 dead cylinders.

I assume when you changed all the ignition components you changed them properly. Make sure you have a bright spark at the points, and a bright spark at the plugs. If not readjust your points. There is a possibility you recieved a bad cap or rotor. It is also possible you have a bad ignition coil.

Are you trying to start your truck with 6 volts or 12?
Are you aware that a 53 gmc would originally be 6 volt positive ground?
Do you have a 6 or 12 volt coil?
If 12 volts, Do you have an ignition resistor?

Please answer these questions if you can.
John

John,
I have poured gas down the carb, both a little and a bit more, but still nothing.
I have not done a compression test as i was just assuming that since im not getting spark off of my block when i hold the spark plug 1/4 inch away, that there is something stopping the ground.
Is there anyway to tell for sure if my truck is positive or negative ground? i currently have it negatively ground and my lights work, heater works, and horn works...
It's running off of a 6 volt, i replaced the 6 volt coil when i changed plugs and distributor ect.

Since the negative ground is grounded onto my starter could there be some sort of interference between the starter and block which is only allowing the starter to be grounded, not the block?

Forgot to mention that there is compression, 1) we can here it when we've been turning over the engine and 2) i stuck my thumb over a plug hole and had my dad crank the engine... im not sure as to how much compression there is but i know there's enough that i have to actually put a tiny bit of strength when holding my thumb over the hole

Just did some more research and 1953 and prior Canadian GMC (which mine is) used Chevy 216.5 not a GMC 228..... would this still mean mine is a positive ground or is it negative ground?

Hy Josh_53GMC, Canadian light GMCs were powered by Chevrolet engines, and were negative ground, hope that helps.

So a 1 ton would actually be a positive ground then, right?

Hy Josh_53GMC, all Canadian GMCs except the 9700 series [3 ton] are negative ground. I saw from your post in the electrical forumn that you have no spark when grounding your spark plug to your engine, as Squeeze suggested you should have your main ground cable attached to a starter mounting bolt, then you can install an additional ground cable back to the frame. That should make your engine crank a little faster, and you might even get it to start, hope that helps.

so it is a positive ground.... oops haha. well she still didnt start... does anybody know the proper way to find TDC without going by the marks on the bellhousing? ive tried every single mark and nothing so im back to thinking it is the timing that we have off. currently i have it sitting a TDC from when i took the valve cover off and turned over the engine until the first intake/exhaust valves were up.

I've given up for today, way too much rain, everything is getting soaked. ill go and purchase another ground strap and hope that she'll crank faster

The ground cable is hooked to a starter bolt and there was no spark (i replaced the ground cable and still nothing) so i finally hooked it up as positive ground and.... i was holding the metal bit of the plug wire... shocking. darn thing hurt

Hy Josh_53GMC. I don't know how I can say it any planer your truck should be wired negative ground, only a 9700 series [3 ton] was wired positive ground. If you check your connections at the ignition coil, you should see that the one with the wire which goes to the distributor is on the coils negative terminal.

if its negative ground then why am i only getting spark to my block when it is positive ground?

Hy Josh_53GMC, I'm not there, and I don't know what you've done to this point. If you remove your number one spark plug and place your finger over the hole and have someone crank it over until you feel the pressure build, stop cranking at that point, and remove the distributor cap, check to see where the rotor is pointing, it should be pointing at the terminal with the number one spark plug wire on it, it may be a little bit before the terminal if you stopped cranking as soon as you felt the pressure. If that turns out to be the case then our timing should be close enough for the engine to at least try to start. If that is not the case then move the number one wire to the terminal that the rotor is pointing at and the rest of the firing order is five, three, six, two, four, in a clockwise direction from the number one terminal, I hope that helps.

i shall give that a try tomorrow, i currently just found my engine VIN so hopefully i can found out now what kind i have.

Thanks for all your help/suggestion 3B

Darn, I missed the part about your truck being Canadian. American GMC trucks were 6 volt positive ground.

Did your truck run before changing all the ignition components?

Years ago I wired my 270 gmc 6 backwards... and it still ran... very poorly, but it ran. Are you sure you wired the plugs in the correct rotation?

As for timing... if the pointer is on the timing mark, your engine will be on the compression stroke for either cylinder number 1 or cylinder number 6. The valve wiggle meathod is one way to figure out which cylinder is on the compression stroke. The finger meathod is another.

I will repeat, if you have fuel and spark, and the timing is close, and the engine still isn't starting, a compression test is in order.

I have no idea if the truck ran when it was parked, but the last time the truck was insured was 1982.
The plugs are wired 1-5-3-6-2-4

HUGE QUESTION! If my truck is supposed to be negative ground then why do i only get spark when it is positive ground??? I have the ground strap attached to a bolt on the starter.

Somebody else will chime in who has more experience with 6 volt systems, but here is how it is done with 12 volt negative ground systems.

A hot wire (Positive +)from the ignition switch goes to the "+" side of the ignition coil. Another wire goes from the "-" side of the coil to the distributor. This might be switched if you have a positive ground system. If your truck is a Canadian GMC with a 216 motor, it should be Negative ground.

The spark should be seen when the engine is cranked, the ignition is on, and the spark plug is grounded to something, weather that is the engine block or the frame, or the inner fender it doesn't matter. If you see a good strong spark, your ignition is good. The spark should be equally bright on the frame or the engine. If not, the engine needs to be properly grounded.

Since your truck has been sitting for almost 20 years...A COMPRESSION TEST IS NECESSARY! It is very likely you have 1 or more stuck valves and bent pushrods.

I'm not sure what a 216 should read on a compression guage, but it is probably somewhere between 125 and 170 psi. If you have compression of 90 psi or better in each cylinder, the engine should start. If you are looking at numbers in the 30 psi range, it is very likely that you have rusted rings, stuck valves, or both.

Please beg, borrow, or steal a compression tester and get back to us.

John

I have currently misplaced my compression tester so until i find it or borrow one from my shop teacher i've stopped trying. dont want to worsen anything if i do have a stuck rod ect