Hello. I recently purchased a 1969 dodge dart, with the 225 inline 6. I have done the usual repairs (fluid changes, spark plugs and wires, fuel pump and line, thermostat, and even carburetor and distributor). The car starts and drives alright except when at idle such as red lights where it begins to tremble and shuts off. I have to start it again and begin to accelerate it while idling to keep it from giving out. I fixed the timing and switched to electrical distributor but the problem has persisted. Any help is appreciated.
I’m guessing the carb needs adjustment, either idle rpm, mixture, or choke settings.
Carburetion includes more than the carburetor. I would guess that it has to do with the fuel/air ratio and upsetting this could be a problem in the carburetor or a vacuum leak somewhere outside the carburetor.
Good idea on the vacuum leak, or a leaking mounting gasket.
If the Dodge has a vacuum advance on the distributor, there may be a hole in the diaphragm on the vacuum advance. You might test the vacuum advance by removing the vacuum hose from the advance unit and plugging it and see what happens at idle. You might also take the vacuum hose to the advance unit and try blowing through it. If you can blow through the vacuum advance hose, there is a bad diaphragm in the vacuum advance unit.
If this is the case, repairing the vacuum advance will not only solve your idle problem, but will give your engine more pep.
Is the choke fully open when warm?
I would remove the air/fuel mixture screw from the carburetor body, clean the tip and spray carb cleaner down into the hole. Then install the screw and gently tighten until the it barely seats. DO NOT tighten, just contact the base. Then back out the screw 1.5 turns, start the engine and adjust for best idle.
I had a 68 with the 318. The chokes were a major problem. I agree with the choke pull off system that can cause major issues and I think they used that coin shaped heat riser device that would always be bad. Replace the pull off, disconnect that coin on the manifold, or put in a manual choke on the thing. Mine was only two years old but I’d drive down to the cafe for coffee and to meet with the boss, come out after coffee, and the dang think would crank and crank before starting again.