Q-Jet adjusting secondaries
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,002
Likes: 0
From: Bay City MI.
Q-Jet adjusting secondaries
How do you adjust when the secondaries open on the Q-Jet? When I hit the gas at take off they open in first, then don't want to open in second, sometimes they open in third and they always open in fourth. Confused, thanks for the help.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Q-Jet adjusting secondaries (467-Ratman)
There is a lock screw under the (passenger side)air valve shaft Loosen it and close the airvalve the preload it by 3/4 -7/8 turn and tighten the lock screw. Also check the choke pull off for vacuum leak. get Lars tuning paper from http://www.corvettefaq.com for lots of good stuff on tuning Q-jets
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Re: Q-Jet adjusting secondaries (467-Ratman)
i assume you are referring to the operation of the air valve
disconnect the spring and linkage and test the rotation of the shaft. the air horn on my carb was slightly distorted from over tightened carb screws. this caused the air valve shaft to bind, which made for really flaky performance. so make sure it operates smoothly before setting the spring tension. Also make sure the valve plates are not catching on the housing.
disconnect the spring and linkage and test the rotation of the shaft. the air horn on my carb was slightly distorted from over tightened carb screws. this caused the air valve shaft to bind, which made for really flaky performance. so make sure it operates smoothly before setting the spring tension. Also make sure the valve plates are not catching on the housing.
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Re: Q-Jet adjusting secondaries (467-Ratman)
Another quick check - with the engine off have a friend sit in the drivers seat and push down the gas pedal as far as it goes. You look inside your Q-Jet and make sure that the secondary throttle plates are sticking straight up and down (open all the way). I beleive one of Lars papers describes how to fix this if your plates are not fully opening. 
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
Re: Q-Jet adjusting secondaries (467-Ratman)
Anybody have a close up picture for me so I know what to adjust? Thanks!
make sure the shaft moves freely.
[Modified by Turbo-Jet, 12:37 AM 7/6/2004]
[Modified by Turbo-Jet, 12:38 AM 7/6/2004]
