mustang runs horribly when engine is warm

[yodabiri]

Hello i have a question regarding how my mustang is running. Its a 65 mustang with 200ci and 3sp and everything is stock. I recentlly rebuilt the carburetor and am planning to get the DUI for the ignition. Anyways the problem is that it runs worse when it is warm. When the engine is still somewhat cold, the car runs great, great throttle response, no surging, no shaking, just smooth and fast! When the engine has been running for a while, the car starts to surge on acceleration, shakes a bit more than usual, hesitates periodically, and the throttle response is increadibly slow!
Also ive noticed that if i turn the choke cap on the carb to make the mixture a bit more rich, the car runs smoother. The engine idles fine when its warm.
Please help me out! Its really annoying and i have tried and tinkered with almost everything to no avail!

Thank you in advance!

 

[Anonymous]

sounds like a carb/choke problem to me...when wa sit last rebuilt? do you know?

 

[Anonymous]

When i have these symptoms it ALWAYS turns out to be a tiny bit of trash clogging the main jet. Of course i usually go through a bunch of checking before i end up pulling the carb top off. Easy things like putting the timing lite on her and then reving it up and making sure the advance is working. Also checking under the hood at night with it idling good and warm, looking for arcing plug wires. A clogged jet on my car will hardly affect cold cranking or even idle as those circuits do not seem dependant on the main jet. Richening up the choke provides enough gas to help some but is real ineffecient and similar to hitting one's finger with a hammer to take your mind off a toothache.

 

[yodabiri]

I was thinking that it was some kind of problem with the fuel system also, so eventually when my car is low on gas, i will have the fuel tank flushed and cleaned out and also the rest of the fuel system flushed. I am getting a DUI distributor soon and plan to change the carb to a holley or autolite 2 bbl also.

Thank you!

 

[Anonymous]

I recentlly rebuilt the carburetor

This is a good reason to check for trash in the float bowl which will clog or partially clog the main jet. When the choke opens up and the engine gets totally dependant on the jet for fuel, any obstruction in the jet will cause a lean situation. Often a pedaling action useing just a touch of the throttle will get you home as the accel pump will provide enough fuel to overcome a clogged jet.