Hey guys,

I'm stumped. A14 with a Weber 32/36 carb starts and runs good initially when cold, but starts to run terribly when hot. The engine has great compression, and was recently rebuilt. When hot, the car won't idle unless I turn in the idle speed screw quite a bit, and even then it's very rough. Seems that no matter what I play with, I don't get any improvement.

So far I have:

-set timing to factory specs (and tried advancing it slightly)
-adjusted valve clearances
-cleaned carburetor, adjusted floats to spec, and replaced jets, needle valve, gaskets, etc.
-eliminated all known vacuum leaks (haven't found any by spraying almost everything with starting fluid)
-replaced spark plugs, wires and such (old spark plugs looked normal)
-checked fuel pressure - it was around 3 psi
-fiddled with the idle mixture screw on the carb but not with different jets

I'm stuck and need some ideas. This car has never run right since I've owned it so I don't have any reference points to go off. Thanks for your help

There is an air leak. A hose is missing, or a gasket is leaking. Or the carburetor has an internal leak.

Ok. I'm almost positive it's not an internal leak in the carb, as almost everything is new. I just replaced the intake manifold/exhaust manifold gasket and valve cover gasket, so I don't think those are it either. As far as hoses missing, it's very possible because the engine is swapped into another car. The only hose connected to anything is the line from the vacuum advance to the carb and I'm pretty sure it isn't leaking. No smog stuff, etc but all the unused ports on the intake manifold are plugged and aren't leaking. I'm not sure where to look now. Would pictures of this help?

Logic is not helping you solve the problem. Instead try a systematic approach.

New carb never did work right? Swap another carb, even the original factory carburetor on there to test if that is the problem.

Makes sense. I'm a student on a very limited budget so I'll keep my eyes open for a working carb to try swapping on.

With further research, it appears the engine is an FU engine (round intake ports.) Could it be that this carburetor doesn't work with the FU engine?

A Weber 32/36 will idle perfectly on an FU engine.

As ddgonzal said, its going to be a vacuum leak. There are ways to test where the leak is - eg spray some WD40 around the manifold gaskets, carby adapater, vac lines etc while the engine is idling. The revs will pick up a little when the engine sucks some in throught the leak.

Problem solved! Worn throttle shafts - fixed using some bearings from a hobby shop. Was hard to pin down because spraying carb cleaner near the area didn't do too much to the idle. However, now it runs like a dream! I guess the "new" carb wasn't so new after all.

Thanks for the help guys.