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54 Pontiac Starting Problems


Jemattson18
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Hi Guys, I have a problem with my 54 Pontiac Chieftain. It was working fine until a few months ago when it sounded like it wasn't running on all cylinders. The next time I tried starting it, it wouldn't start at all. It sounds like there's a few cylinders firing, but not enough to actually get the engine running.

 

I was wondering if any of you have any suggestions as to what the problem could be. Since I started experiencing this problem I have replaced the spark plugs and spark plug wires and made sure that the spark plug gaps were correct. I also made sure the points gap was correct. I checked each spark plug and I am getting spark to each cylinder. I have also rebuilt the carburetor and did a compression test.

 

One thing I noticed was that when I removed the carburetor, half of the intake manifold had gas pooling in it. It's a carter WCD carb with two barrels and this is the barrel closest to the engine. After cranking the engine I can look down inside and see this pool of gas too. I can't imagine this is normal and was wondering if this could be the reason the engine wont start.

 

Any help or suggestions are appreciated.

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What were your compression numbers?  Does it try and run now after your carb rebuild and new spark plugs?  Did you check the cap and rotor,  does the cap have any hairline cracks?  How is the timing, is it suddenly off?

Edited by TerryB (see edit history)
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Sorry for the late response. So I did both a dry compression test with the engine cold and then a compression test with some marvel's mystery oil squirted into the cylinders.

 

Dry test --- #1- 50 psi   #2-60 psi   #3-40 psi   #4-30 psi   #5-32 psi   #6-58 psi   #7-60 psi   #8-52 psi

 

Wet test --- #1- 105 psi   #2-112 psi   #3-100 psi   #4-110 psi   #5-80 psi   #6-105 psi   #7-105 psi   #8-110 psi

 

Now, I know the pressure was low in cylinder 4 and 5 during the dry test and in #5 during the wet test, but it sounds like the engine is firing on much less than 6 cylinders.

 

The car acted the the same after rebuilding the carb and replacing the spark plugs and spark plug wires. One thing I didn't replace when I rebuilt the carb was the float needle valve. The rebuild kit I have has float valve that's a different design than the original which is why I originally didn't replace it. I took the valve apart and cleaned it and it looked good but I think I might replace it with the one provided in the kit this weekend.

 

I looked at the cap and rotor and cleaned it off as best I could. I don't see any hairline cracks in the cap either.

 

Like I said, there's a lot of gasoline pooling in the intake manifold so I think it might be a problem related to the float valve. The gasoline is from September and I put sta-bil in it in December so I would imagine it's still good. I'm going to replace the float valve and try it again and let you guys know how it goes. Thanks for the help.

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I would suspect the old gas that's been in there since September. I had a similar situation last winter with an old flathead six car with stale fuel. I drained it all out, poured some fresh gas in the tank, it fired right up and it's been running fine ever since.  A mechanic friend of mine insists that today's gas has a shelf life of 45 days. 

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Possibly the carb needle/seat is leaking and flooding the cylinders

Washing down the cylinders.

Loss of compression end result.

Plugs black or wet with fuel possible.

Maybe install new needle/seat...lube the cylinders again lightly,  new plugs and fire it up.

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Replacing the needle and seat is reason number 1 for rebuilding a carburetor. I share your concerns about the different design, and don't have a lot of advice about that. I am using modern "Daytona" one with a flat needle in my 36. I may have had to lower the float slightly but I can't remember for sure.

 

Steel needles have come back into vogue because of fears about ethanol. The way I remember it, steel needles just barely worked when they were new, and the "viton tip" float valves (pointy rubber needle) solved a whole bunch of problems when they came along. Today people don't want to use those because the ethanol allegedly destroys them. Personally I would roll the dice and use one if it came in the kit because I remember how much trouble steel needles were.

 

Set the float to factory spec according to the service manual or the rebuild sheet. Set up all your choke settings to factory spec too (don't skip this). Then, assuming your car is not prone to backfiring (and wear goggles, etc.), look down the throat. Choke open, there should not be gas running out of anything up there (like the dischage tube in the venturi) period. Crank engine for some fuel pressure. The only thing that should discharge any gas up there is the accelerator pump squirter, and only when moving the throttle. If gas is "running over" or boiling out up there, the float is set too high. Lower it a tiny bit and retry.

 

Start with factory settings though, because float height is critical to make the carb work right. Lowering the float unnecessarily will cause more problems.

 

 

Edited by Bloo (see edit history)
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Lots of folks have the mistaken idea that steel needles are uneffected by ethanol:

 

Steel needles

 

My guess is old fuel.

 

Lots of folks don't like starting fluid, but I have personally used it for over 50 years with no issues.

 

I would suggest a helper to crank over the engine for you. While it is being cranked, short squirts of starting fluid (NEVER when the engine is not turning over).

 

With new wires and plugs, and spark at each cylinder, it should start. If it starts, run it at a high idle until warm. Then it may idle on the old gas.

 

I had a similar issue with a low compression tractor that sat all winter. Wouldn't start cold on old gas. Get it started on fluid and run at high idle until hot, then would start on the old gas, as long as the engine was hot.

 

That "45 day shelf life" posted by another gentleman above is generous!

 

Jon.

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Thanks, you guys are a huge help. This weekend my dad and I replaced the float valve on the carburetor with the flat rubber valve that came with the Daytona rebuild kit. We did have to adjust the float down a little bit because with the floats all the way up, it wasn't seating the valve. We had the carb cover upside down so that the floats were at the highest level and the float valve was closed and there was a little bit of a gap between the float and the valve. We adjusted the floats down just a bit so that they were making contact with the float valve when the floats were all the way up. We tried starting it again but it wouldn't stay running. It ran basically the same as it did before. There was still some gas sitting in the intake manifold, however so I think that might be why it didn't run. I'm going to try and swab out the manifold so that it's dry and start it again. Bloo, I'll follow your advice and look down the throat and make sure nothing's dripping down into it when we crank it over again.

 

You guys might be right about the old fuel too. We've sprayed some starting fluid and it'll start firing on that but won't stay running. It's amazing how bad ethanol fuel is. I'm going to try and just get straight gasoline for this car from now on.

 

Again, thanks for the help. I'll keep you guys updated.

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So I emailed Daytona Parts, which is where I bought the carb rebuild kit, asking what they recommend the float height to be. They sent me a page from what looks like a Carter WCD technical manual and that says for a '54 Pontiac to set the float height at 3/16". Before I had set it at 3/32" because that is what I had read in a different manual. So, last night I took the carburetor off, set the float height to 3/16" and cleaned out the intake manifold as best I could so that there wasn't any gasoline sitting in there. When I put the carburetor back on the car, however, it still wouldn't start. It acted exactly as it had before. As my dad cranked it over, I looked down into the barrel and couldn't see any gasoline leaking out anywhere. Even holding the butterfly valves open I didn't see any gas leaking out anywhere. Gas sprays out of the nozzles when you open the butterfly valves, but I understand this is normal. While cranking over, we sprayed some starting fluid down the intake and when we did this we could hear the engine start to fire and at one point I thought the engine was actually going to start and stay running.

 

We decided to buy a carburetor from Carburetor center just so that we know we have a good carburetor and can rule that out. Does anyone have any experience buying a carburetor from them?

 

In the meantime, I'm going to drain the gas tank and put some new gasoline in the car. Hopefully that fixes the problem.

 

Stay tuned...

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BEFORE buying a different carburetor:

 

Take the airhorn off of the existing carburetor.

Use a paper towel or rag, and remove ALL of the fuel

Put the airhorn back on the carburetor.

Find a ketchup or mustard squeeze body, empty the food? contents, clean, and fill with FRESH gasoline.

With the squeeze body, fill the carburetor through the bowl vent.

Now try starting the engine again with starting fuel.

I believe it will start, and idle about 10~15 seconds on the fresh gasoline.

 

If it does, drain the tank.

 

And as Bloo stated in the post above, if you must have a different carburetor, KEEP your old one!

 

Jon.

Edited by carbking (see edit history)
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2 hours ago, carbking said:

BEFORE buying a different carburetor:

 

Take the airhorn off of the existing carburetor.

Use a paper towel or rag, and remove ALL of the fuel

Put the airhorn back on the carburetor.

Find a ketchup or mustard squeeze body, empty the food? contents, clean, and fill with FRESH gasoline.

With the squeeze body, fill the carburetor through the bowl vent.

Now try starting the engine again with starting fuel.

I believe it will start, and idle about 10~15 seconds on the fresh gasoline.

 

If it does, drain the tank.

 

And as Bloo stated in the post above, if you must have a different carburetor, KEEP your old one!

 

Jon.

When you had the carb apart, did you remove the mixture screws and clean the needle end ? Reset them to 1 3/4 turns out from closed position. Sounds to me like you may not be getting idle fuel.   Did you use any air to clean passages out...? Only takes a speck of dirt at the wrong spot to block fuel...

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Thanks for the advice. Carbking, I'll try your method this weekend and let you know how it goes. Why do you guys suggest keeping the old carburetor?

12 hours ago, john hess said:

When you had the carb apart, did you remove the mixture screws and clean the needle end ? Reset them to 1 3/4 turns out from closed position. Sounds to me like you may not be getting idle fuel.   Did you use any air to clean passages out...? Only takes a speck of dirt at the wrong spot to block fuel...

 

Yes, when I took the carb apart I actually replaced the mixture screws with new ones that came in the rebuild kit. I believe they call them idle adjustment screws in the manual I have. I also screwed them in until they seated and then backed them out 1 3/4 turns as it states in the manual. I didn't have any compressed air, but I made sure to blast out every passageway with carb cleaner.

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41 minutes ago, Jemattson18 said:

Thanks for the advice. Carbking, I'll try your method this weekend and let you know how it goes. Why do you guys suggest keeping the old carburetor?

 

 

I know nothing about the company you mentioned with the rebuilt carburetor, so the following is a general statement:

 

Since the 1950's, the commercial carburetor rebuilders have "grouped" carburetors together to reduce inventory. To accomplish this, holes were drilled to accomodate tubes for various vacuum requirements on the various carburetors grouped, parts often are used from various carburetors in the grouping, and the final calibration is set to be the richest of the carburetors in the group.

 

To give an example: some time ago, had a customer with a 1965 GTO and a commercially rebuilt carb that ran, but not overly well. I had him get a lot of numbers on the carburetor, and was able to determine that he had a 1963 main body, a 1965 top casting, primary clusters from 2 different years (don't remember which), and a calibration for a 421 with automatic and A/C (instead of the 389 with standard transmission).

 

As stated earlier, I know nothing about the company that you mentioned; but the odds are that the carburetor you have is better than the rebuilt carburetor you will buy. The "core" charge probably is not a lot; just makes good sense to keep what you have.

 

Jon.

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4 hours ago, carbking said:

 

I know nothing about the company you mentioned with the rebuilt carburetor, so the following is a general statement:

 

Since the 1950's, the commercial carburetor rebuilders have "grouped" carburetors together to reduce inventory. To accomplish this, holes were drilled to accomodate tubes for various vacuum requirements on the various carburetors grouped, parts often are used from various carburetors in the grouping, and the final calibration is set to be the richest of the carburetors in the group.

 

To give an example: some time ago, had a customer with a 1965 GTO and a commercially rebuilt carb that ran, but not overly well. I had him get a lot of numbers on the carburetor, and was able to determine that he had a 1963 main body, a 1965 top casting, primary clusters from 2 different years (don't remember which), and a calibration for a 421 with automatic and A/C (instead of the 389 with standard transmission).

 

As stated earlier, I know nothing about the company that you mentioned; but the odds are that the carburetor you have is better than the rebuilt carburetor you will buy. The "core" charge probably is not a lot; just makes good sense to keep what you have.

 

Jon.

Thanks, that's good to know.

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More to the point, the "grouped" carburetors Carbking refers to usually don't work right. The day will come, probably sooner than later, when you can't stand screwing with it anymore and will need to do a proper rebuild. You will need a good core that hasn't had random orifices and jets drilled out. Good cores are hard to find. You probably already have one.

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  • 1 month later...

Hey guys, so after a lot of head scratching and trying different things I finally got this car running again last night. Last night I replaced the cap and rotor and tried to start it but got nothing. After that I shortened the wire going from the coil to the distributor because it was looking a little sketchy at one end and it was about twice as long as it needed to be anyways. I also replaced the points and condenser and set the gap and after that the car started and ran just about perfectly. I got to tell you, it's one of the best feelings in the world to fix a problem like this.

 

What I think originally happened was that the fuel in the tank went bad back in November-December and between then and replacing the fuel, the condenser either went bad or I messed up the points from monkeying around with it. Either way, now it's been fixed and seems to be running great. Thank you guys for your help.

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