1952 Pontiac Chieftain Spark

[MercMontMars]

Hi everybody, I’m back at my Pontiac trying to get her running. I’ve been juggling my time and projects and finally found the time to rebuild my starter and work out the kinks in my ignition system. 

Everything is officially “working” as in my carburetor is good, fuel pump is good, distributor is good, plugs are good and coil is.. possibly good. I can never really tell with these things, I’ve had a lot of bad luck with modern coils. 
 

So the point I’m at right now is getting her to fire. I can use 6v again to turn the motor now that my starter is fresh and I’m getting blue spark at the plugs and points. Everything is looking great, but I just can’t get her to fire. I’m not certain about my firing order, and my manual isn’t very helpful about telling me much. Only things I’m questioning is compression and fuel. When I last broke down it felt like a fuel problem, the acceleration got finicky and the motor died out. I probably flooded it trying to get going again and she hasn’t run since, but it’s had a while to evaporate so I’m not sure if this is the issue. My other suspicion is compression, I haven’t done a test with that yet and need to go get a test kit but I’m not sure if it’s the issue. I don’t think a motor would suddenly die from that on the road but who knows.

 

All I know is I haven’t run the motor since I broke down, I’m getting spark and possibly fuel but air could be the problem OR my firing order is wrong.. if I’m lucky it’s that.

 

Anyone else been in my shoes with their Straight-8? Any advice and firing order diagrams would be very helpful.

 

Thanks for any help!

 

 

 

 

 

Edited October 3, 2023 by MercMontMars (see edit history)

[Bloo]

Firing order: It's cast into the side of the block isn't it? 1-6-2-5-8-3-7-4 maybe?

 

Do this to see if you are "180 out". Take the plugs out, put your thumb over #1 and turn engine over until it tries to blow your thumb off a little. Bring it the rest of the way up with a wrench or something until the timing marks are at TDC. Now you know you are on the compression stroke, and not the exhaust stroke. Where is the rotor pointing? This is number one.

 

If the rotor is not pointing the way Pontiac says it should be, the distributor may be inserted wrong. You can decide now whether to correct it. You do not necessarily need to correct it to make it run.

 

Note which way the rotor turns. I think it's counterclockwise, isn't it? Anyhow, put the #1 wire in the distributor cap tower the rotor is pointing to. Put the rest of them in, following the firing order, going around the cap in the same direction the rotor turns.

 

Edited October 3, 2023 by Bloo (see edit history)

[Oldtech]

That is correct firing order.

[MercMontMars]

@Bloo Yup, I did the order counter-clockwise. I put the motor to TDC according to the marks on the balancer and installed the distributor, and it seemingly points to 1 which would be correct. I don’t fully trust this though, I’ll have to physically feel where the motor is to be 100% accurate. Once that’s all sorted and I still don’t get anything it’s gotta either be my compression or wires, as they aren’t the best and are what came with the car when I bought it. Still have to go grab a compression test kit to test that too. 
 

[Bloo]

6 minutes ago, MercMontMars said:

I put the motor to TDC according to the marks on the balancer and installed the distributor, and it seemingly points to 1 which would be correct.

Are you sure you were on #1 TDC compression stroke and not #1 TDC exhaust stroke?

 

 

[MercMontMars]

No actually, there are three notches on the balancer that are very close together. I was on the one in the center. I’ll get a photo of it next time I’m by the car, which one should I be on?

[JACK M]

Do like Bloo suggested. The thumb test.

If it's on its compression stroke TDC and the firing order is correct, try pouring a bit of gas down the carb. Sometimes just cranking won't prime the pump.

[MercMontMars]

Compression on cylinder No. 1 so far.. I am supposed to have a 7.7:1 compression rate I believe. Gonna check them all but I’m probably in store for some new rings.

 

[Oldtech]

1 hour ago, Bloo said:

Are you sure you were on #1 TDC compression stroke and not #1 TDC exhaust stroke?

 

 

Bloo is asking that the # 1 cylinder is on compression. On a 4 stroke engine it only fires every second revolution. You can be on the timing mark, but not the compression stroke, NO GO.  Hence the "thumb test"

[WPVT]

2 hours ago, JACK M said:

Do like Bloo suggested. The thumb test.

If it's on its compression stroke TDC and the firing order is correct, try pouring a bit of gas down the carb. Sometimes just cranking won't prime the pump.

I would second the priming suggestion. In my experience, often the fuel pump is capable of supplying fuel when the engine is running, but sometimes not good enough to pump at starter speeds. You don't realize this normally, because the fuel bowl in the carb usually has fuel in it, and that is enough to start the engine. If the car sits, or runs dry, or if it is turned over repeatedly without success,  then the bowl may be empty. A quick check is to have someone pump the accelerator while you look into the carb (engine not running). If you see or hear gas squirting, then you have gas. If you don't, the bowl is empty (or your accelerator pump doesn't work.

If you disconnect the fuel inlet at the carb, and use a squeeze bottle (like they use for ketchup) to inject gas into the bowl, then you can either start the engine, or eliminate lack of fuel as the problem. 

 

[MercMontMars]

So I’ve got good fuel and spark now, and she was making combustion but I can’t get her to turn over. Fuel bowl squirts well, I had the carb rebuilt a while back. She rolls about 4-5 times then let’s out a big backfire. I have a feeling it’s timing now, or my order could still be off.(by distributor positioning.) I felt the first cylinder for TDC and lined it up with one of the balancer lashes. My distributor rotor pointed to 1 and I made this 1 on my distributor. Went counter-clockwise 1-6-2–5-8-3-7-4. Gonna continue tinkering with it, might adjust my points too. Tested all my cylinders’ compression and each one tested around 60-65psi and went up to 120 when oiled, not exactly great. 

Edited October 4, 2023 by MercMontMars (see edit history)

[Bloo]

1 hour ago, MercMontMars said:

She rolls about 4-5 times then let’s out a big backfire.

 

Are you REALLY SURE it is timed on the COMPRESSION STROKE? It has compression on all cylinders, so no reason to believe an intake valve might be stuck open. No reason for a backfire.

 

When you are 180 degrees out (timed on the exhaust stroke rather than the compression stroke, the engine will alternately backfire (through the intake) and afterfire (through the exhaust). Most mechanics never see a car 180 degrees out often enough to catch on exactly what this sounds like when you crank, but once you do, and realize what you are listening to it sticks with you forever. POW!......puhh......POW!......puhh......POW!......puhh......  It might not be nice and and even popping like that but the sound is still unmistakable once you know.

 

1 hour ago, MercMontMars said:

or my order could still be off.(by distributor positioning.)

With the marks at TDC, the rotor needs to point at number one or the opposite cylinder in the firing order. Since the firing order is 1-6-2-5-8-3-7-4, the opposite is number eight. That is two ways it could be pointing by just looking. The two possibilities alternate every other crankshaft turn. They are either both right, or both wrong. You can't tell which is which by sight. That takes either a thumb on a spark plug hole, or a hiss from a compression tester hose, or the side covers off so you can see what the valves are doing. Of course if the rotor is not pointing at either of those cylinders with the marks at TDC, it is definitely wrong.

 

I guess your timing chain could have jumped, that would explain low compression, but I don't think the numbers would come up much with oil if that was the problem. I don't think that happened. Anyhow, I wouldn't worry about low compression too much right now.

 

1 hour ago, MercMontMars said:

 

Where's the condenser? You need it.

 

1 hour ago, MercMontMars said:

I have a feeling it’s timing now,

 

Make sure the points are actually opening. If you think the timing is way wrong, a Pontiac typically has 3 marks close to each other. The first 2 to come up to the mark are 6 degrees BTC and 3 degrees BTC if I remember correctly. Pontiac expected you to be normally running between those two. The last mark to come up is TDC.

 

Connect a test light between the points lead and ground. Get the rotor pointing almost to number one. and watch the light as you crank the the rest of the way to TDC on number one. The light should come on right around the timing marks. Don't go backwards or timing chain slop will screw up your results. If you go past, go on around another turn. Get it set so the light comes on either right at the first mark (6 degrees) or somewhere in-between the two (6 degrees and 3 degrees). That will be close enough to run, and maybe even perfect, but once running you can check with a timing light.

 

But before you do that, make triple sure it is not 180 degrees out. Maybe do the thumb test again.

 

Edited October 4, 2023 by Bloo (see edit history)

[Frank DuVal]

1 hour ago, MercMontMars said:

So I’ve got good fuel and spark now, and she was making combustion but I can’t get her to turn over.

Turn over is what the starter does to the engine. Run is what you are missing. i.e it turns over but does not run.

 

Don't adjust points if you have spark, and your picture shows spark. 

 

Backfire usually means distributor is out 180 °.

[MercMontMars]

@Bloo Thank you Bloo, I appreciate your diligent advice. I think that’s what I was experiencing, it was a sound I’ve never heard before and I saw backfire from the intake/carb. I definitely won’t be forgetting it any time soon..
 

Condenser is in place, it’s just hidden behind the rotor in the photo. I will be using all your advice tomorrow as I work on her, hopefully ending the day with a running straight-8.

 

Edited October 4, 2023 by MercMontMars (see edit history)

[rodneybeauchamp]

My understanding is even a worn engine with low compression will still run if properly timed.
 

Three things required for an engine to run are fuel, spark and compression.

 

Timing is critical and as mentioned is easy to be out by 180 degrees or the firing order (spark plug wiring) is incorrect.

 

If you have a service manual then timing is explained step by step but you MUST be on the compression stroke for it to fire.

 

Just my two bobs worth of experience with engines that eventually run

Rodney 😀😀😀😀😀😀