1950 Straight 8 Engine Heats Up & Quits

If you removed the riser the carb is always going to overheat .

I’m almost certain that your Buick has a coil resistor. Trace the primary lead from the coil and see if it goes to a unit on the firewall. As I remember,these resistors were about an inch and a half long and 3/4 of an inch wide and were often white. On some cars,the resistor was under the dashboard. Our neighbor had a 1946 Ford and when the car was hard to start, he would bridge the coil with a half dollar to get more voltage to the coil.

When this quits, have you ascertained that there is fuel in the carburator fuel bowl? Have you done a fuel pump pressure and flow test both cold, hot, and when the engine stalls? Modern fuels are rough on mechanical fuel pump internals i.e. diaphragm and valves. As mentioned previously, check the suction line for soft hoses and possible air leaks. Also these old engines were susceptible to vapor lock if the suction line came anywhere near hot engine parts.

Keep us in the loop when you find the solution to this problem.

Are the plugs sooted black? Do you smell gasoline as the engine warms up prior to stalling?

Next time it quits, pull the coil wire out of the distributor and have someone crank the engine with the key on. Hold the coil wire near any metal and you should see the spark jumping. If not, it’s an ignition problem. If you have good spark, then you have no fuel delivery. By removing the heat riser, you REMOVED carb heat, not created it. This will make warm-up’s very slow in the winter time…The old fuel pumps will not tolerate the ethanol in todays fuel. A REBUILT fuel pump will, as the rubber diaphragm will be made out of upgraded material…

Assuming your car has a 12 volt system, there will be a coil resister someplace. There should two wires going to the positive side of the coil. One goes through a dropping resistor and the other supplies full battery voltage when cranking. The coil itself will be a standard 6 volt coil…

So first, figure out if it’s spark or fuel causing the problem…

Unless this 1950 Buick has been modified, it would have a 6 volt negative ground system. Even so, most cars with 6 volt systems had coil resistors. I know that the 1952 Dodge my parents owned had a 6 volt system and a coil resistor. Buicks didn’t go to a 12 volt electrical system until 1953 and then only in the Super and Roadmaster models. The Buick Special didn’t adopt a 12 volt system until 1954.

A condenser failure can very easily do what you’re describing and there is no test for a condenser.

Spark or fuel? What are we trying to fix??

I would bet it is the coil or the condenser. I don’t think it has a resister. As someone said, it should have a 6 volt system unless it has been updated. And yes, removing the heatriser will lessen the heat to the carb., taking longer to heat up. I worked for GM building Buicks in the 50s and they went to a 12 volt system in '53, except the Special, which was a straight 8, got the 12 volt system in '54. I bought a 53 Special new.

I’m assuming here the OP has verified whether the carb has gas in it or not when it quits.
If the carb has gas and the coil has been replaced then the condenser would be suspect to me.

It’s also possible for a coil to jump a spark with a faulty condenser but that spark will not be strong enough or consistent enough to fire across a plug gap that is under pressure.
So this means eyeballing a plug that is laid on top of the engine block for a spark is not a 100% sure test. I discovered this the hard way, several times, about 30 years ago.

I have never seen a points ignition fail because of a failed condenser…I’ve seen a lot of failed points ignitions…BILLIONS of perfectly good condensers have been thrown away in the course of doing the annual 12,000 tune-up on points ignition cars…

Minor Tune Up = Points, plugs, condenser, set dwell and timing, adjust carb.
Major Tune Up = Points, Plugs, Condenser, cap, rotor, wires, set dwell & timing, adj. carb.

Also performed. Clean and lube distributor, check operation of vacuum and centrifugal advance mechanisms. Check distributor cam for wear and shaft for play.

While I agree that condenser failure is comparatively rare, I have seen condensers fail. Contact points that are prematurely burnt on one side or the other can be due to a bad condenser (assuming it’s the correct farad rating) and a stinking bad condenser (less than a 1000k miles on it) on an antique Harley left me cursing life on the side of the road one time in the TX panhandle on a 100 degree day.

Uneven point wear caused by arcing is not a sign of failure but a sign the condenser does not match the inductance of the coil…A common problem…Now Harley condensers, well, what can I say? At least they were better than Lucas…

My guess is you have “vapor lock” meaning the gas is vaporizing in the fuel lines before it gets to the carb. This is like a bubble that “blocks” fuel flow. Cars of the era were subject to vapor lock. Modern cars with high pressure fuel systems don’t have a vapor lock problem and modern fuels aren’t blended with any concern regarding vapor lock.

You might be able to reduce the heat around the fuel line by covering the fuel line with insulating materials in the engine compartment. You may need to be sure the carb itself is cooled either by more ventilation, or perhaps some insulation on or around the carb too.

When I was a kid we had a '52 Ford with a flat head V8 that would vapor lock frequently in the summer. We carried a jug of water and when it died in an intersection we’d get a push out of the way pop the hood and pour the water on the fuel pump and fuel lines from the pump to the carb and we’d be underway again in a flash. Without the water jug you’d pop the hood and wait about 15 to 20 min. and then it would fire up and off you go.

It happens at lower speeds because the lower flow of fuel allows more time for the fuel to heat up and vaporize in the fuel line from the pump to the carb. Carry a gallon jug of water with you and try the water cool technique if it works you know the problem. Then all you need to do is come up with a solution.

Install an electric pump back by the tank.

You haven’t said exactly when the engine quits. Does it simply stall at idle, or will it quit even if running at higher speeds?

Buicks from later on in the '50s had a nasty habit of percolating the fuel in the carburetor float bowls and stalling if allowed to idle for very long. I don’t know if earlier, straight 8s had similar problems. I think I’d insulate the fuel lines from exhaust heat everywhere I could though, just to rule that out.

I think caddyman is right when he suggested the distributor shaft. When they get worn out, the points begin to fluctuate and at worse, cause the engine to quit. Turn the engine until the points just start to open, then try to move the shaft around with your hand. If its worn, you can see the points open and close. It could also be the condenser.

edit: nevermind my reading comprehension is calling it quits. Good night.

Vapor lock, choke stuck ethanol, the high voltage ignition system… Any one could be the problem.

My point is that a faulty condenser can and does cause point arcing and metal transfer. A condenser going bad does not automatically mean the engine ceases to run immediately either; it can resemble running out of gas, vapor lock, or what have you.

So how many Harleys and Delco-made Harley condensers have you owned and how much tune-up work on Harleys have you actually done?