Just incase this has been asked before I apoligize but I couldn't find a thread about it. Lately when I start my car the idle is real low. So low that I need to give it gas or it will stall. It's even worse in the winter. I have the orginal 4bbl rochester carb that came with my 305 but everything else (including my new 350) is different. After the car is running and warmed up, it will sometimes idle at 800 rpm like it's suppose too. But it is rare. How do I adjust it? I think all I need to do is adjust the idle but if not im open to suggestions.

 

There are two idle adjustments on the carb, the "fast" or choke idle, and the "curb" or warmed up idle. Sounds like you've got an issue with the former and the latter is fine.

The fast idle is a function of the choke closing and a cam pivoting to engage the fast idle adjustment screw. First thing is to verify the choke is closing completely when cold - you do that by removing the air cleaner when the engine is stone cold and opening the throttle slightly - the choke butterfly should snap closed and a green weight on the passenger side of the carb should move up. The other end of that green weight has the idle steps built into it that the adjustment screw engages. If the choke doesn't snap shut and/or the weight doesn't move up, make sure those mechanisms and linkages move freely - being gummed up is a common source of problems with the choke. If they move freely but don't act properly, your choke thermostat is probably shot (the round plastic can on the passenger side of the carb).

If all that is okay, there's one more possibility, the choke pull-off is opening the choke too much when the engine is started. It should only open a few 32nds of an inch at first. A fairly simple adjustment if needed.

If everything does what it is supposed to as described above, you need to do a simple adjustment of the fast idle screw to bring the idle up.

 

The carb is the one part of my engine I know very little about. I know I had the choke thermostat replaced before by my mechanic because it was bad. Where exactly is the fast idle adjustment screw? Is it possible you could refer me to a picture or something?

 

https://www.thirdgen.org/forums/carb...qjet-need.html

Post #24, items 88 & 89. Also some good links in that post.