Holley carb

Hi guys,
Just finished my '27 "T" pickup and all is well. I do have a problem with the curb idle. The carb is an old holley 4160 on a 305 chev. I rebuilt the carb and it runs fine, but won't idle down under about 1200 rpm. I note that the throttle shaft on the arm side is pretty sloppy in the throttle plate hole. Will that cause a fast idle? I cant find any vacuum leaks that might be causing the fast idle. I've successfully rebuilt many of these style carbs before and haven't done any thing different.
Thanks,
Olguy

 

Depending what you mean by sloppy, sounds like you found your vacuum leak.

 

http://www.chevelles.com/forums/showthread.php?t=165331 see post number 10 secondary transfer slot adjustment

 

Try spraying the throttle shaft see if that don't slow down the idle RPM

 

Have you changed the camshaft? If so you may not have enough vacuum at idle, so have to increase RPM to get it to idle.
If this is the case drill a small hole in the primary throttle plates on the same side as the transfer slot.

 

You have "two" things going on with sloppy throttle shafts.

1. A vacuum leak between the throttle body and the shafts.

2. Since the butterflys are round, and the throttle shafts are loose...when closing the throttle, the butterfly blades get hung up on the i.d. of the throttle body bores rather thAn sitting nicely on the actual throttle stop.

Time for a rebush of the throttle shaft bores or a new carb.

Mike