l have a 1973 Lincoln continental sedan. 460, 8 cyl, carborated OH V. Car runs great at 190 degrees(cold).After a brief shutdown of 10-15 mins and restarting hot at 220-250 degrees the engine mis fires during acceleration. The question is do l have a failing carburetor or burnt exhaust value?
Coil has been replaced, distributor is new, spark plug wires are new, Spark plugs look like lightly toasted bread. l have eliminated ignition malfunction.

>> The question is do l have a failing carburetor or burnt exhaust value?

Do a cylinder pressure test to check. l would think it is the carb as they are notoriously difficult to keep running well..


Good Luck.

Neither one. Check u spark plugs, plug wires, & engine timing. The conditions u describe especially with a big block V8 at 35 to 36 years old make me think u have one of the following:
1. Spark plug fouling causing the plug not to spark due to excessive oil being thrown into the cylinder.
2. Deteriorated spark plug wire creating an open circuit break when the engine gets hot preventing the plug from being fired.
3. Loose distributor / failing advance mechanism causing the spark to be to advanced & or delayed causing a mis-fire.

You might have a failing spark coil.

A carburetor problem on this engine usually results in bad hesitation at any temperature or stalling not mis-firing.

A valve not sealing on this engine, one to three you'd barely notice. More than that & this engine probably would not even start.

my guess is the timing and its either off or your timing advance is not working correctly and being as old as it is if you have not changed the timing advance l would do that regardless and then set the timing.

Sounds like a timing problem or worn valve guide seals. Check fuel filter and fuel pressure .

Sounds like carb. Engine is suppose to stay around 190 degrees, 220 or above water may boil over.