Warm start issue

[jlutz455]

My issue is my 73 455 Trans Am q-jet.  It will start and die after sitting at work, from say 8-noon. Happened today and the temperature was 80 at noon.  I have to feather the gas to keep it running then it will get better and idle fine again if I drive about 1/2 mile. Does seem to idle rougher though than when fully warmed up.

I live in S. Florida , have the choke setup (i believe) correctly as the car will start perfectly in any cold condition...3 pumps of the gas, starts right up and idles at 1000rpms until choke opens then idles at 750.

The carb appears to have been restored and when I took it apart and took some measurements, has some mods already done like idle tubes drilled to 0.039" and the bypass drilled to 0.110". Also idle mixture screws were drilled bigger...forget the measurement.

There was brown epoxy smeared over the pressed in plugs, but it was leaking.  I ordered the epoxy kit from Cliff and put that in. It runs better, but still has this warm start dying issue.  Any ideas ?

Thanks!!

[Cliff Ruggles]

.039" idle tubes would be HUGE for a 1973 Pontiac carburetor.  Even the big 800cfm Super Duty Q-jets in 1973 only had .038" idle tubes.  Not sure what the other items measure for the idle system, or what tuning parts are being used, so really can't provide much assistance......Cliff

[jlutz455]

Just an update for anyone else that suffered from this problem. Took carb off and found the plugs leaking bad. Took out the set screws, re epoxied it, let it set up for 24 hours and reinstalled carb.  Works great now!! Cold starts take one full pump of gas, fires right up, fast idles at 1000 rpms,  Then if the car sits for say 4 hours and I go to lunch, just turn the key, let it crank and lightly touch the gas while cranking. settles into nice 850 rpm idle.  Car also starts right up if say running multiple errands.  Get in, just turn the key and NO gas. fires right up and settles into 850 idle again.

So....moral of this story is pull the carb if all else fails and check for leaking main and secondary leaks in the pressed in or epoxied plugs. Also gives you a chance to set the idle screws and transfer slot exposure to what Cliffs book shows so you know that's right.