And the choke is wide open and has released the secondary latch on the right side.
Quadrajet Secondaries
Thread Starter
Le Mans Master
Joined: Apr 2013
Posts: 5,000
Likes: 1,056
From: Arlington TX
2024 C1 of the Year Finalist - Unmodified
2023 Restomod of the Year Finalist
2023 C1 of the Year Finalist - Unmodified
Quadrajet Secondaries
Before I replaced my unbuildable Qjet, there was a definite sound of "Waah" when kicking in the secondaries, and a rush of power. I can't seem to get that back with the Jet Performance Quadrajet I've been tweaking.
I've followed Lars paper on setting the secondary spring windup, secondary rods seem right compared to his data, and I've set the hanger height, but I only get a slow increase in power and not the Waah. I don't think the secondaries are opening. Linkage isn't the factor.
Any ideas? Is it the spring windup, the rod diameter, or something else?
I've followed Lars paper on setting the secondary spring windup, secondary rods seem right compared to his data, and I've set the hanger height, but I only get a slow increase in power and not the Waah. I don't think the secondaries are opening. Linkage isn't the factor.
Any ideas? Is it the spring windup, the rod diameter, or something else?
Melting Slicks
Joined: Sep 2004
Posts: 3,223
Likes: 666
From: Northeast
The Lars' paper I have reads "If the secondaries are operating correctly, the transition into the secondaries will be so smooth that there should be no kick feeling at all- only smooth acceleration". ".. that secondary kick is an improperly set up secondary air valve....".
When setting my air valve I needed to pull off the highway and adjust the setting so that I did not get that kick. Been on the dyno and dragstrip & it works well.
Adjust the spring setting and see what happens on the highway if you think everything else is operating correctly. I found out on my first dyno day that the air valve did not open at all.
When setting my air valve I needed to pull off the highway and adjust the setting so that I did not get that kick. Been on the dyno and dragstrip & it works well.
Adjust the spring setting and see what happens on the highway if you think everything else is operating correctly. I found out on my first dyno day that the air valve did not open at all.
Instructor
Joined: Jun 2008
Posts: 233
Likes: 9
From: Marietta Ga
This is exactly what happened to me. With the pedal to the floor, the accelerator linkage only pulled the secondaries part way open. Super easy adjustment to the cable..... I was way overthinking it. Hope its that simple for you.
Thread Starter
Le Mans Master
Joined: Apr 2013
Posts: 5,000
Likes: 1,056
From: Arlington TX
2024 C1 of the Year Finalist - Unmodified
2023 Restomod of the Year Finalist
2023 C1 of the Year Finalist - Unmodified
The Lars' paper I have reads "If the secondaries are operating correctly, the transition into the secondaries will be so smooth that there should be no kick feeling at all- only smooth acceleration". ".. that secondary kick is an improperly set up secondary air valve....".
When setting my air valve I needed to pull off the highway and adjust the setting so that I did not get that kick. Been on the dyno and dragstrip & it works well.
Adjust the spring setting and see what happens on the highway if you think everything else is operating correctly. I found out on my first dyno day that the air valve did not open at all.
When setting my air valve I needed to pull off the highway and adjust the setting so that I did not get that kick. Been on the dyno and dragstrip & it works well.
Adjust the spring setting and see what happens on the highway if you think everything else is operating correctly. I found out on my first dyno day that the air valve did not open at all.
Interesting. Still, I love to hear those secondaries kick in...
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
You can check the throttle cable movement with engine OFF. Just don't do it any more than you need to get it set properly, as each time you exercise it, there is some raw fuel dumped into the manifold. Do it a lot, and there's LOTS of raw fuel in the intake. (Could be exciting if you start it up like that! 
)
As mentioned above, test the throttle movement by having someone in the car depress the accelerator pedal. Testing it manually by moving the carb linkage is NOT the same thing!!!
With accel pedal depressed FULLY, hold the upper secondary air valve wide open and make sure the choke is fully released. Then look down into the secondary venturi and make sure the throttle plates are completely vertical. If they are not, make adjustments to throttle cable and/or carb linkage as needed to get them fully open.
)As mentioned above, test the throttle movement by having someone in the car depress the accelerator pedal. Testing it manually by moving the carb linkage is NOT the same thing!!!
With accel pedal depressed FULLY, hold the upper secondary air valve wide open and make sure the choke is fully released. Then look down into the secondary venturi and make sure the throttle plates are completely vertical. If they are not, make adjustments to throttle cable and/or carb linkage as needed to get them fully open.
