Hey Everyone!

i have a 302 with all the stuff in my signature on it, and its a fresh rebuild. the piston rings haven't even been broken in yet.

My problem is my truck has a weird idle. in order to get it to fire, you gotta give it a healthy amount of pedal, and have to keep giving it gas in order for it to stay running. the strange part is sometimes when you let off the pedal for a bit the rpms will stay high (by ear, probably around 2500-3000) for a few seconds then drop down again, while other times it will just drop until it eventually bogs out and stalls. it sounds fantastic, no chatter, exhaust leaks or anything.

I suspected it might be the carb, so i have adjusted the float levels, and they are in the ballpark (I can't fine tune this stuff with one hand on the throttle ) i haven't done anything with the idle mixture, because i can't keep it running long enough to do anything....plus i can't find the right size allen wrench...lol.

I have tried raising the idle speed, but i have a 4180C holley carb, and based on pictures ive seen, this carb doesn't have a idle speed screw. am i missing a crucial part, or does this carb really not have one?

I have the spark plugs at .40, and i can't set my timing yet. i've swept the distributor through the range where the engine will still start (not knowing the exact degrees), and it still wants to die if you stop giving it gas.

is the ignition, or carb to blame? and how would i go about fixing this? is this due to 10 month old gas not really cutting it? next time i stop by work (i work at NAPA) i'm going to pick up some seafoam.

 

My first thought is a vacuum leak