Don't know if this is a carb problem but I'll pitch it out there. I recently bought an 83Z LG4 with a 4 barrel quadrajet carb. When I fire up the car, it jumps to 2300 to 2800 rpm and stays there. It never drops down to idle rpm. Is this a carb tune problem or something else?

 

Most likely it is something holding the throttle blades open. Could be the choke high idle cam (meaning the choke isn't disengaging the high idle cam for some reason), gummed up works, bad throttle cable, improper adjustment, etc.

 

Thanks, I removed the carburetor and everything seems to be working ok mechanicaly but I have a question. Are the blades controlled by electronic sensors? How does it know when to idle down?

 

Maybe this has something to do with it?

http://www.partsgeek.com/catalog/198...oid_relay.html

 

What does this screw control. It does affect idle speed but the idle becomes very rough.

 

Looks like the air valve spring adjuster.

this link has alot of info and diagrams on quadrojets

http://vetteworks.tripod.com/qjet.htm

 

I'll check into that connection. Thanks. There are two electronic connections on the carb. I'm guessing one is for the choke but don't know what the other is.

 

Just saw your link. Lots of great info. Thanks!

 

Should be three.

read, learn, live:

https://www.thirdgen.org/forums/carb...e-rebuild.html

 

That's the "vacuum break"/"choke unloader" adjustment screw. Sets how much the choke butterfly is opened when the engine first starts.

If that affects your idle when the engine warms up, for sure your choke isn't opening.

 

There is no power wire connected to your choke thermostat. That wire provides 12 volts to the choke thermostat coil to warm it up so it opens the choke. Find that wire and hook it up. It's a single wire.

 

Genius! I'll try to track it down. The harness is butchered.

 

and a smurf threw up on your motor

 

Haha. I think it's from lack of air flow.