When I was 13 I totally rebuilt my fathers 47 Buick Roadmaster since it was burning oil. I had qquite a lot of experience with that car! One thing it was guilty of was vapor lock. I recall one time waiting in the instpection station line in NJ on a hot summer day. The engine quit and wouldn’t start, so I opened the hood and wrapped some rags around the fuel line which ran above the exhaust manifold. I poured some water on the rags and a few minutes later was able to start the car and take it thru inspection. The guy behind me in line was quite surprized that a 14 year old kid knew so much about cars, but that was my life at the time! Good luck!
Ok I?ve read all the post and your replies here.
I?m betting you don?t have a spark or a very weak spark.
You stated you haven?t checked for spark, but in the past when it wouldn?t start you?d give it a shot of ether.
Ether evaporates much easier than gasoline and ignites much easier, and once its running you make a better and hotter spark.
I don?t think it a vapor lock problem because you can see fuel in the filter that would mean it was only boiling in the carburetor and while I have seen that most vapor locks you wouldn?t see fuel in the filter. After all if your fuel pump can keep the filter full of fuel it should be keeping the carburetor full also.
I?m wondering if you bought the right coil, you stated that it said ?NO EXTERNAL RESISTOR REQUIRED? that might mean it has an internal resistor and isn?t a 6v coil but a 12v coil, if I remember right coils are 6v and you used a resistor to kick the voltage down from 12v to 6v. So if you have a coil with an internal resistor it?s not getting enough voltage. As it heats up it requires more voltage to make a good spark and you?re not putting enough voltage to get a good spark.
When you say it?s ?obviously marked 6V? where is it marked I haven?t seen a coil that says it?s for a 6v system.
My opinions are subject to change with new facts.
Once again, I suspect the problem is the coil. Years ago a lot of coils would fail when they got hot.
I did not mean to twist the shaft, I meant push it side to side, in several directions. You should have been able to twist the shaft, if not, your mechanical advance is stuck. For that, find the springs and weights and spray a little oil on them to free them up. Your engine will run better.
I read your post saying you suspected the coil too, and according to the OP he replaced it at some point. I wanted to point to the reason why I thought that way. It also could be the a small crack that when hot gets big enough to allow the spark to take a different route other than going down the spark plug wire. That happened to me once.
Personally I think the OP should take the following steps once it stalls check for fuel then spark, bring a friend and a tow rope. Drive around until it stalls.
Once it quits, make sure you are getting fuel. Pull the filter use a can to catch the fuel have friend crank over a few time, two or three cranks should put fuel into the can. This would be a good time to check the fuel temp. If you have fuel, then check for spark. If I was a betting man I’d put my money on spark.Once you know which system is giving you the problem then you can take trace down the part(s) that are giving you the problem.
My opinions are subject to change with new facts.
by the time I had checked 60 posts I forgot that OP had changed the coil.
This may sound goofy but way back in my early years ;my Dad and I ran into a Buick that wouldn’t run and adter all the checking it turned out to be a clogged oil filter, the oil runs up to the rockers and down to the lifters ;and they dwere not getting the oil to work.
Would that keep it from starting? I know that it would ruin an engine to run it that way.
I may add, the oldest car that stumped me with an overheat condition was a 1950 Chevrolet 235 I-6. Seems the owner did not clean out the head bolt blind holes (required for head or head gasket replacement, these engines were know too crack heads) and it had the smallest HC leak into the coolant. Took about 75 miles to reach 220F
After this and we still don’t know what’s missing; spark or gas.
Based on the ether comment one has to assume no gas; short of a coincidental problem like a bad ignition switch, condenser, etc.
Earlier I mentioned the heat riser and its possibly sticking. As I follow this thread the possibility of that being the cause remains likely. When stuck in the closed position the exhaust and intake manifold will get very hot, especially under the carburetor, The heat riser eliminates icing and greatly reduces the warm up time needed to drive normally but the flapper must open as soon as the manifold is hot. If it remains closed,vapor lock in the fuel line, flooding due to the fuel evaporating in the hot bowl, and the subsequent fowliing of the plugs is likely. Even the most basic engines can be difficult at times.
Search vapor lock using Wikipedia. Your problem was very coming in the 50’s and 60’s. Been there, experienced that!
Could be, but it was running fine, and this would be an odd time of year for vapor lock. But it would be very helpful for the OP to put a pressure gauge on the fuel line near the carb and see if anything’s wrong on the fuel side.
I think OP said he removed the heatriser.
When it has this problem, remove the air cleaner and operate the throttle. If no gas squirts into the venturi, it’s a fuel problem.
I am not an expert but have been surfing on Buick I8s last few days.
I have read several post discussing the manifold problems with the Buick straight 8.
Apparently the carb heat valve in the manifold gets stuck and it will boil the fuel.
See if the carb heat valve is free.
The problem of vapor lock on the Buick straight 8 engine is addressed in this month’s “Cars & Parts” in the monthly technical column by Earl Duty. Apparently, the line from the fuel pump to the carburetor passes over the valve cover and is near the thermostat housing. One reader suggests clamping wooden clothes pins on this secion of the fuel line or insulating the line or rerouting the line if the problem you are having is, in fact, vapor lock. This column can be found on pages 64 and 65 of this issue of Cars & Parts.
One other suggestion: If your problem is vapor lock (and I am not certain that it is), you might try premium fuel that has a higher ignition point and vaporizes at a higher temperature.