QJet Idle Problems
Thread Starter
Race Director
Joined: Jul 2002
Posts: 13,858
Likes: 0
From: A 12/8 man in a 4/4 world
QJet Idle Problems
senario:
79 qjet.
No choke or choke linkage.
Problem
Idle is either 2000 RPM usually cold or just at temp or it drops to the point of stalling.
runs great at cruise and at WOT.
The stalling usualy happens at operating temp.
runs great at cruise and WOT.
Ideas?
I believe my timing is set correctly.
79 qjet.
No choke or choke linkage.
Problem
Idle is either 2000 RPM usually cold or just at temp or it drops to the point of stalling.
runs great at cruise and at WOT.
The stalling usualy happens at operating temp.
runs great at cruise and WOT.
Ideas?
I believe my timing is set correctly.
Last edited by Disco_Mike; Jun 2, 2007 at 09:45 AM.
Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
Why no chojke or choke linkage?
I had a similar problem and it turned out that someone in the past had removed the choke pull off and the fast idle cam and when they put it back on they did not attach the cam at the bottom of the choke linkage to the cam off the fast idle.
The result was the car would not hold idle until it was real warm. Prior to warming up it would only run if you held idle at 1500 RPM. As soon as you backed off the gas it stalled. Choke butterfly was not movable even by hand.
I pulled the fast Idle cam and threaded it thru the choke and it worked great. The choke needs to be closed at startup and then slowly open as it warms up. If it doesn't it will be hard to start and even harder to hold idle.
I had a similar problem and it turned out that someone in the past had removed the choke pull off and the fast idle cam and when they put it back on they did not attach the cam at the bottom of the choke linkage to the cam off the fast idle.
The result was the car would not hold idle until it was real warm. Prior to warming up it would only run if you held idle at 1500 RPM. As soon as you backed off the gas it stalled. Choke butterfly was not movable even by hand.
I pulled the fast Idle cam and threaded it thru the choke and it worked great. The choke needs to be closed at startup and then slowly open as it warms up. If it doesn't it will be hard to start and even harder to hold idle.
Racer
Joined: Jul 2006
Posts: 336
Likes: 10
I removed the choke of my 77 Qjet. I am very pleased with the results. The engine start first try with 5 accel petal pumps, I wait for about 30 seconds, sometimes playing the throttle a bit, before backing out of the shop. It idles nice at around 500 and rises to 800 when warm. Idles at the same RPM at every stop light, seems to have better response with restriction gone. No crap hanging off the carb!! I think the choke system is the most complex part of these carbs.
Be sure to plug the vacuum port to the coil chamber!
Be sure to plug the vacuum port to the coil chamber!
Thread Starter
Race Director
Joined: Jul 2002
Posts: 13,858
Likes: 0
From: A 12/8 man in a 4/4 world
I dont drive the vette in really cold temps.
I had trouble with it occasionally sticking.
The only thing I really notice is if im not up to temp and the secondary try to kick in it bogs. (no choke = no secondary lock out)
btw, I did know to plug the coil port.
my vette is up to temp in a few minutes anyway.
I had trouble with it occasionally sticking.
The only thing I really notice is if im not up to temp and the secondary try to kick in it bogs. (no choke = no secondary lock out)
btw, I did know to plug the coil port.
my vette is up to temp in a few minutes anyway.
