ZZ430 idle speed
Thread Starter
Intermediate
Joined: Feb 2007
Posts: 48
Likes: 4
From: Apopka Florida
ZZ430 idle speed
Alright, haven't posted on here in forever but anyways, I've got a 78 Corvette with a kit built ZZ430 with 650 Speed Demon carb, LT4 hot cam, 1.6 ratio rockers and Vortex Fast Burn Aluminum Heads. The issue I'm running into is getting the car to idle, i rebuilt the carb recently and haven't had much luck getting the car to idle below 2.5-3k and the internetz haven't been much help finding info on what the idle speed should be. 
Racer
Joined: Mar 2008
Posts: 315
Likes: 0
From: KY
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Alright, haven't posted on here in forever but anyways, I've got a 78 Corvette with a kit built ZZ430 with 650 Speed Demon carb, LT4 hot cam, 1.6 ratio rockers and Vortex Fast Burn Aluminum Heads. The issue I'm running into is getting the car to idle, i rebuilt the carb recently and haven't had much luck getting the car to idle below 2.5-3k and the internetz haven't been much help finding info on what the idle speed should be.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Sends shivers down my spine when I hear rebuilt carb and won't idles below 2500RPM in the same sentence. Could be anything not rebuilt properly to a properly rebuilt carb and not setup correctly 
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
So you are ruling out there was no problems with the rebuild ? It is perfect, you put it back on the motor like it was before and now it idles at 2500-3000RPM.
Shouldn't do that if everything was done correctly do you agree with that ?
Look for vacuum leaks sometimes you forget a vacuum hose PCV or brakes or lights and the idle with go up, make sure any unused vacuum ports are sealed
Shouldn't do that if everything was done correctly do you agree with that ?
Look for vacuum leaks sometimes you forget a vacuum hose PCV or brakes or lights and the idle with go up, make sure any unused vacuum ports are sealed
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
I've come across this before on a street legal drag car, the owner thought it was the big cam that was stopping it idle. Turned out he hadn't plugged the brake booster outlet 
Also are you sure the cam and ignition timing are correct?
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