strange idle problem - i'm stumped

[Bobby]

I can't seem to get the carb tuned right. I have the Holley 4160 and I recently rebuilt it. I followed all of the instructions and whatnot and I still have a problem. It will accelerate just fine with no hesitations and it runs strong with good fuel delivery. Once it drops down below 1k rpm it bogs down and dies. I have all new gaskets for absolutely everything and the PCV valve is still good with a new hose running from it to the carb, so it shouldn't have a vacuum leak. The floats in the bowls have been measured to their correct positions and the fuel is doing what it is supposed to from what I can see. This has given me a problem for quite some time now and I'm about to break down and just go get a new carb out of sheer frustration. Anyone know what I need to do?

[ffmedic74]

RE: strange idle problem - i

Are you sure its not a bad fuel pump?

[Bobby]

it's getting plenty of gas so i don't think it would be a bad pump. it will rev up strong, just when it dips below 1-1.5k rpm it just dies.

[surroundsound64]

Did you set your metering block correctly? For that carb and your altitude the screws on the metering block should be approx 2 1/2 turns OUT from seated.

This may be a dumb question but I'll ask anyway... did you get all the parts back in it? That carb has a bowl transfer tube that when left out will still allow the engine to run, but as you describe, not idle. I think it's the 4160 that will do that anyway... I quickly looked online for a schematic of it but couldn't find anything.

[Bobby]

2 1/2? I've never tried that before, I've always heard 1 1/2 and that has always worked out well for me in the past.

I'm pretty sure the carb is 100% back together, I went back in and took it apart just to put it back together to make sure everything was there.

[surroundsound64]

I moved here from Duncan almost 2 years ago... 2 1/2 always is always what I used on mine at that altitude. If 1 1/2 is what you had been using and it worked then keep using it.