Alright Y'all, I have to ask ya how to adjust my carburetor. It has been giving me hell over the past couple weeks.

To start off, 1980 F100 with 302 V8, complete rebuild with flat top pistons, mild cam, high rise aluminum manifold, Holley 650 4 barrel with vacuum secondaries. SO, The issue I was having was out of nowhere, the truck would stall out when I came to a stop going forward only, in reverse it would not stall out when coming to a stop. I read a couple ideas of what it could be, went to a couple shops in town, I adjusted the float in the secondary bowl, fuel level was a little high, lowered it back down, moved the idle adjustment screws to factory then adjusted to get highest vacuum, Idle was moved to 1000 rpm in order to keep the truck from stalling out. If I lowered the idle back down to 850-900 rpm the truck would stall out again, even with the floats and all mentioned above adjusted. I have kept the truck at 1000 rpm for about a month now and now I am noticing that when the truck was turned off, the engine would continue to crank over for about 3-4 strokes and then stop. Not liking that.. So I am at a standstill at what needs to be done, extremely annoyed because none of the shops in town will help me. I am located now in crossville, TN. The shop that rebuilt the engine is located in Fayetteville, NC, and I cannot just hop up and drive 7 hours to get a carb adjusted.. Hopefully someone here can help me out with this extremely confusing and annoying issue I am having. Thank you.

 

Hey have you checked for vacuum leaks ???
That's what it sounds like to me.

 

Double check the float levels again front and rear. You should be able to pull the plugs with no fuel leaking out. And then bounce the fender with your body weight and some fuel will slosh out. High bowl levels can cause this, when the fuel level is high and you hit the brakes it can spill over into the engine and make it stall. The rear level is hard to adjust, since so little fuel is used back there. If you find it's still high when you check the rear bowl, lower the level way too low, and then take it out and open it up to use the fuel up back there. When you come back it should be really low, and then you can carefully bring it up a little at a time, till it just sloshes out when you bounce the fender.

If that's not the problem, I would take each mixture screw and turn them out exactly 1/4 turn from where they are now, and see if that helps any. Make sure any adjustments you make are with the idle down slow, with the idle at 1000 you really can't make any idle mixture adjustments, because you are not at idle.

 

Thank you franklin, I greatly appreciate the info. I was on the right track with adjusting the rear bowl float level, but you are correct and I will re-check all levels and just verify everything is where it should be, and as for the vacuum leaks, I have checked every area where vacuum lines exist by spraying carb cleaner on all connections to hear for higher rpm, so that ruled that out. Thank you for the swift reply and I will post tomorrow with the results.