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1950 Straight 8 Engine Heats Up & Quits

Hello, I have a 1950 Buick that quits when it gets hot.Simple as tinker toys,right? It’s gotten progressively harder to restart.I need to let it cool much longer than the 20 minutes or so it used to take.I’ve replaced the coil & carbon core plug wires (with solid core wires). They both may fail when hot if already weak.Have replaced the points also & boiled out the carburetor, which had some corrosion in the bowl.Thermostat

appears OK, temperature doesn’t rise above usual. Haven’t had the courage to take it out on the road again. This simple ignition system has me awfully frustrated. Has anyone got a good idea?

Are using gas with ethanol? If so, you shouldn’t be. The fuel system in your vehicle isn’t designed to handle any amount of ethanol. And if you are using gas with ethanol it makes the fuel system more suseptable to vapor lock.

Tester

Does this car have a 6 volt system ? I once worked on a 53 Vauxall Victor that had a bad coil and the new coil acted like yours. Found out the parts store had given me a 12 volt coil.

Are the points and timing set to spec? What is the condition of the radiator?

Yes, make sure you have a 6-volt coil regardless…You may need to install an electric fuel pump back near the tank to overcome the vapor locking caused by todays high vapor-pressure fuels…Your local airport, if you ask them nice, will sell you 10 gallons of 100 octane low-lead…The old Buick will LOVE that!!

Check for spark when hot. If no spark, it’s ignition. If spark, then it’s fuel. You didn’t say that you tried another condenser. How does it quit? Suddenly or does it run poorly and then die?

There is a heat riser valve/stove in the exhaust manifold. If stuck in the closed position the engine will stall at idle when hot. The valve has a counter weight visible just above the tailpipe connection to the exhaust manifold. There is a bi-metal thermostat spring attached at the counter weight. The counter weight should be free to move with hand pressure. Don’t burn your hand. If memory serves me, the counter weight should be down (valve open) when hot.

Yes, am using gas w/ ethanol, but have been for a number of years now, that’s all that’s available hereabout. And it ran alright. It began quitting just recently; I’ve had it for 19 years. Thanks.

Are you trying to fix an overheat condition, a no crank (or slow crank) or a good crank with a engine that won’t fire, or all three at times?

I’ll check the part # on the new coil. Thanks.

The points are spec & the timing slightly ahead.This engine has a peep hole in the bell housing for timing & I haven’t been able to manage a good look into the mouse hole.I’ve timed it by trial & error, until lately it’s run very smoothly. Radiator’s alright, temp doesn’t rise anymore than usual on the temp gauge.Have watched that closely.Thank you.

Do you mean once it gets hot the engine will not crank? If so 2 possible causes of that are not enough oil flow and carbon buildup in the cylinders. It is possibly spraying lots of water into the carb while running could help clear it out if it is carbon buildup.

I don’t recall if I switched the condenser; will have to check.It had been starting easily & running well even when into operating temp range, then bucking & backfiring at some point, then quitting. I used to be able to wake it up w/ a small shot of ether, but lately the engine doesn’t respond to that. This has evolved from a small hassle into large predictable one.Thanks.

I removed the heat riser when I replaced the exhaust pipe a few years ago.Thanks.

This is a real shot in the dark, but you might want to check the fuel line from the gas tank to the fuel pump. A pinhole leak may cause the mechanical pump to suck air and stall the car. It sounds like a fuel problem if you can start athe car with a shot of ether.

The engine cranks well & starts easily when cool; then runs rough & quits after it’s been at operating temp for awhile. No overheating. Will crank well but not fire when warm.The no-fire when warm is the problem. Thanks.

No, the engine cranks well when hot. Used to start again after cooling for 20 minutes or so, but lately won’t start that quickly. Need to let it sit for several hours.Thanks.

If the ignition is failing when the car has been run, the problem may be the coil resistor. This resistor limits the voltage to the ignition points so that the points don’t burn out prematurely. After so much current has passed through the resistor, it may open up with the resulting loss of voltage to the igniton points. When the car has cooled, the resistor closes and functions normally.

I USED TO be able to start it w/ ether when hot, indicating spark available, but not lately. The problem has gotten progressively worse until now, when I have to let it get cold before it’ll start.

I’ll have to look at that. I can’t visualize a coil resistor on that engine; I’m not sure it’s ever had one. I’ll look at it soon. Also check my old auto book to see whether there’s supposed to be one there. Thank you.