My 79 cutlass with a 455 built engine came with a Holley double pumper carburetor
it had the manual choke bypassed with a little rod

I decided to install a manual choke and after doing a bit of research I adjusted the fast idle screw to bring the rpm to 1400 ish on choke

however when I do this my regular idle is high with the choke off like 1100-1200 rpm

Ive tried adjusting it numerous times but I’m guessing once choke is off it should idle to whatever the running idle screw is set for

I know this carburetor is old but any tips or suggestions on why this is happening?

I do plan on getting this rebuilt but still not sure if it will fix the problem or should I just get a new one ?

on a fun note. I’m assuming the fast idle screw opens the secondaries ??

because I feel a massive difference in response and power when I was adjusting the screw and it would idle around 1200

 

Check throttle shafts for any play in them. It causes a vacuum leak. Carb will not idle well at all.

 

I did perform a smoke test to check for vaccum leaks but none found

it idles fine

just not when you adjust the fast idle choke screw

 

You should be able to set your warm idle where you want it first with a mix of ignition timing and with the curb screw on the primary (shoot for a square transfer slot) and the curb screw on the secondary (you have to take the carb off to adjust this from underneath on most Holley carbs). Finally, you can adjust the high idle screw on the choke to get the idle you want when the choke is set.

 

Thanks.
I will get this rebuilt first as it’s probably 12 years old now without it being touched.

the rebuilt guy I’m using said he will adjust it as he rebuilds it

 

It sounds like the fast idle cam is sticking and not dropping all the way down. Or the choke is not really opening all the way. Can you post a close up picture of the fast idle screw area when you are having the problem ? Exactly which model number Holley is it ?

 

Thanks. I have disconnected again until it get rebuilt