# 350 timing issue



## levilynch (Sep 28, 2020)

So for starters this is my first time dealing with timing. I just replaced the GM HEI cap and rotor on my 73-74 model Pontiac 350 motor and now it doesn't start it only turns over. I have both spark and fuel. I carefully marked all the wires and the points on the distributor to match that of where they were on the old one and went through one by one. Currently the engine is at 0 degrees on the compression stroke and the rotor is pointing where I have the number one wire connected or close to. Each of the wires are marked for the correct firing order on the block but I'm not sure if that order is correct on the distributor cap. 

Cap and marked wires. Engine at 0 degrees compression stroke rotor pointing at or close to wire 1 connection.


----------



## PontiacJim (Dec 29, 2012)

levilynch said:


> So for starters this is my first time dealing with timing. I just replaced the GM HEI cap and rotor on my 73-74 model Pontiac 350 motor and now it doesn't start it only turns over. I have both spark and fuel. I carefully marked all the wires and the points on the distributor to match that of where they were on the old one and went through one by one. Currently the engine is at 0 degrees on the compression stroke and the rotor is pointing where I have the number one wire connected or close to. Each of the wires are marked for the correct firing order on the block but I'm not sure if that order is correct on the distributor cap.
> 
> Cap and marked wires. Engine at 0 degrees compression stroke rotor pointing at or close to wire 1 connection.
> View attachment 141078


As long as you are using the correct firing order diagram, and have #1 positioned correctly at the cap in relationship to the diagram, you should be OK. Pontiac firing order on the cap goes counter clockwise, not clockwise like a 350 Chevy - unless you have a Chevy 350. So make sure you are using the firing order diagram for a Pontiac 350, same as any other 400, 455, etc.. Early Pontiacs put the No. 1 spark plug wire where the No. 6 wire would go on later Pontiacs. Make sure correct year firing order diagram as well.

You probably have slop in the timing chain and wear in distributor gears, so you may have to play with the distributor positioning - I have had to do this myself. Just move the distributor around by hand until you get it to fire off. Keep in mind that Pontiac rotor rotates counter clock wise, or to the left. Turn the distributor to the left will be retarding the timing/firing. Turning the distributor to the right, will be advancing the timing. My guess at this point is that you want to turn the distributor to the right to advance it. Just watch how much you turn it from your intial point. If it does not pop, or fire off, then go the other way. If it pops, or almost wants to fire, then you are going in the correct direction with the distributor.

Get the engine to running well and ignore your timing marks for now. Advance the distributor and listen to where the engine sounds smooth, then you can time it to dial it in. You probably want around 10-12 degrees seen on the balancer - and then you can adjust/road test from there.


----------



## levilynch (Sep 28, 2020)

PontiacJim said:


> As long as you are using the correct firing order diagram, and have #1 positioned correctly at the cap in relationship to the diagram, you should be OK. Pontiac firing order on the cap goes counter clockwise, not clockwise like a 350 Chevy - unless you have a Chevy 350. So make sure you are using the firing order diagram for a Pontiac 350, same as any other 400, 455, etc.. Early Pontiacs put the No. 1 spark plug wire where the No. 6 wire would go on later Pontiacs. Make sure correct year firing order diagram as well.
> 
> You probably have slop in the timing chain and wear in distributor gears, so you may have to play with the distributor positioning - I have had to do this myself. Just move the distributor around by hand until you get it to fire off. Keep in mind that Pontiac rotor rotates counter clock wise, or to the left. Turn the distributor to the left will be retarding the timing/firing. Turning the distributor to the right, will be advancing the timing. My guess at this point is that you want to turn the distributor to the right to advance it. Just watch how much you turn it from your intial point. If it does not pop, or fire off, then go the other way. If it pops, or almost wants to fire, then you are going in the correct direction with the distributor.
> 
> Get the engine to running well and ignore your timing marks for now. Advance the distributor and listen to where the engine sounds smooth, then you can time it to dial it in. You probably want around 10-12 degrees seen on the balancer - and then you can adjust/road test from there.


Thanks Jim. While I was waiting for a response I had found an earlier thread spark plug wires to distributor that made mention that I had the wires on in the correct sequence. I figured my issue was with the position of the cap in relation to the rotor and did what you said about turning it clockwise until it ran smooth. Seemed like I was able to keep advancing it until one of the arms on the cap ended up hitting the vacuum coming off the distributor.

Where would I see the most wear in the distributor gears? the one underneath the rotor?

How frequently should the timing chain be replaced as well as the distributor?

Is it normal for the entire distributor to come out leaning slightly over to the driver side? I'll need to get a timing light to dial it in better. Any tips or links for ways to really get the most out of my distributor would be appreciated. Thanks!


----------



## PontiacJim (Dec 29, 2012)

levilynch said:


> Thanks Jim. While I was waiting for a response I had found earlier an earlier thread spark plug wires to distributor that made mention that I had the wires on in the correct sequence. I figured my issue was with the position of the cap in relation to the rotor and did what you said about turning it clockwise until it ran smooth. Seemed like I was able to keep advancing it until one of the arms on the cap ended up hitting the vacuum coming off the distributor.
> 
> Where would I see the most wear in the distributor gears? the one underneath the rotor?
> 
> ...


The gear is at the end of the distributor in the engine where it meshes with the gear on the camshaft. Not often they wear out, but they can wear and just give a little extra clearance/play between the 2 gears as they mesh - but not a big concern. The distributor shaft can get loose withing the distributor housing just from wear/age. You should not be able to "wiggle" it if you grab the shaft/rotor and move it side-to-side. It may have up/down play which can be normal. Not too often you will need to replace a distributor, if anything, the electronic module under the rotor and having the wires going to it can quit on you. If it does, the car will crank, but not start as you won't have any spark. Heat is usually what causes them to fail over a period of time.

Check your timing to see where it is at as you may not need to advance it any more, or may even need to back it down (retard) if too much advance. If the vacuum advance can on the side of the distributor is hitting and you cannot rotate the distributor any more, but need to to get timing right, you can rotate the distributor away from the part it is hitting, and move your wires back/forward 1 distributor cap hole to match the amount you moved the distrib. housing. Then just fiddle with the distributor again to get it running good and then dial it in from there. Not the most scientific, but that's how I do it when I drop in a distributor once I get the rotor lined up with the No. 1 spark plug wire in the cap.

Timing chains can go out around 60,000 miles - gears wear and chain can get loose. Depending on year, I believe it is the 1973 and earlier engines used the nylon coated "silent" cam gear and the nylon gets brittle and chips off. You can test the chain/gears for wear by rotating the engine by hand and watching the rotor move. So you will need to remove the distrib. cap to view the rotor. Go in one direction, and then back - does not need much of a turn at the crank and you don't have to bring the balancer up on No. 1 cylinder for this. Simply rotate the crank/balancer to the right by hand to take up any slack in the chain. Make a mark, or chalk line on the balancer at the timing scale at the 8 degree or 3/4 lines up on the timing scale, turn to the left and stop the second you see the rotor move. Note how many degrees the timing mark moved - should only be about 4 degrees, or 2 lines on the timing scale. Then go back right, and watch the rotor and stop when it moves. It should end up at 8 degree or 3/4 line on the timing scale where you started. You can repeat to double check your results. If the mark goes 6 degrees or more on the timing scale, the chain/gears are worn - the more degrees you can move the balancer/mark along the scale before the rotor moves will tell you how worn the chain/gears are. Don't use the starter to bump over the engine, you must turn it by hand if possible or use a socket/ratchet on the balancer bolt, or Alt, or PS (if belts are tight enough) as you are not going to move it much.

The harmonic balancer on a Pontiac has an outer inertia ring bonded to an inner hub. Miles/age will cause the rubber bond to deteriorate. This can allow the outer ring to move so the timing mark on the outer ring is no longer accurate - so you can have a problem trying to time the engine and can't figure out why it runs good at 20 degrees advanced when factory says 9 degrees and when you put the timing on 9 degrees it runs real poor, the ring has slipped. A new balancer is inexpensive and cheap insurance because if it were to come apart (not a common thing) it can do engine damage. So most will just replace with a new balancer.


----------

