hi everyone. Im hoping someone knows the answer to what is probably a pretty simple question. I have a 302 with a holley 600 carb on it. it starts fine and idles fine and drives fine (although it doesn't stop very well). the problem I'm having is if I just punch the gas briefly while completely stopped when returning to idle it just dies. I just noticed this problem when pulling into my dads barn to work on the car. there is a slight hump in front of the door and I just pushed the gas and let the throttle plates snap shut, and when returning to idle it died. not something that will give me problems very often but I'd like to take car of it. is this a tuning problem?
Holley Have you tried to set the float level on smooth surface? Idle speed ok?, have seen instances of leaking power valves, squirters, and throttle plates closing to far and restricting air passage. Justs sounds like a rich fuel air mixture after squirting a charge into the throttle body etc. at idle speed. Just a secondary thought, check the condition of the plugs and timing setting too. Plugs can tell alot about engine functions and fuel burn effeciency.
it idles at around 800 and in gear is at 600. and it's fine when I shift it into gear and when I drive it's fine. it doesnt have any problems when I put a load on it like if I have the wheel turned all the way to one side. sometimes when I crank the engine to start it when cold I have to hold the pedal all the way to the floor. there is a manual choke on the carb but it seems pretty worthless, the holley doesn't even seem to repond to it much. I don't know if the mixture is set to rich or what. when I screw in the mixture screws the idle goes up but they're almost all the way in so it's almost completely leaned out. it seems to run about perfect other than that one problem. plenty of power and a strong idle unless I just punch the gas and let up. if I rev it high and let up it returns to idle fine. but if I just give th gas a little punch it stumbles.
Does this car have long duration camshaft in ? Air condiditoning ? What is the ambient temperature ? Another thing to consider that I have seen happen is when you give a little bark and let off right away the fuel that was squirted out tends to make a seal around the throttle plates which effectively negates all signal to the idle circuit . If this is the case you could try to close the secondary throttle plates a little manually . But be warned you are opening a whole new can of worms by doing this .
like old guy suggested, perhaps the float level is too high? That would be the most likely cause I would think. Also, I have actually done this...but sometimes the gasket at the power valve will be off center slightly and cause slight leakage. Makes tuning a real pain. Good luck, and keep us posted
