Holley High Idle
 

just resently I got the new motor runnin in my car, 355 sbc in an 89 iroc. Its got a Holley 670 street avenger on it, electric chock, vac secondaries. Once the choke comes off itll idle at around 600rpm(stick car). However when I hit the gas the idle will go up to anywhere from 800-1200rpm. I noticed the throttle linkage isnt returning all the way. I adjusted the idle screw so far that its not even touching anymore. I can push on the linkage and the idle will go down to 600 but come back up once I let go. I figured the return spring was too weak so I bought a CSR throttle bracket with double return springs on it. I can get the idle to hold at 600 but the spriings are so tight I can barely press the gas pedal. The problem has to be somewhere else. Everything on the motor is new so I know the carb linkage isnt all gummed up or anything. Anyone got any ideas?
Matt

I'm just guessing but I'd say your butterflies maybe rubbing. I've fixed that by loosing the screws on the thottle shaft and then gently open and close the throttle until the butterflies are free, then retighen the screws.

X2..just don't take the screws all the way out they are smooged over on the ends to keep them from backing out.

Also I would still adjust the speed screw back down until it at least touches.

The screws on the throttle shaft are the ones that hold the butterflies in place. One for each butterfly? Just want to make sure Im picturing the correct ones.

Also check the plastic cam on the throttle side it can cause a bind and this type of problem. Not sure what this cam is called but it has a flat screw and 2 or 3 adjustments...

Nope there's two(2) screws for each butterfly, you'll have to remove the carb and then remove base plate to access them.
Then just slighty loosen the screws per bore (4) then rotate the shaft a couple times to center the butterflies up and enure there is no binding and tigten them back down, recheck your work and put it back together.
Hope this helps.
Goodluck, Charles

Does it do the same thing with the throttle cable unhooked? The cable may be too short or need adjusted to let the throttle close completely.....

Yup still does it with the cable off

Camaro430 have you adjusted the butterflies yet?

i agree Butterflys or a snug trottle shaft thaat needa little working in

take the carb off and look at it from all sides,over and under while you pull the blades open...you should be able to feel the drag while the carbs are in your hand...