Throttle cable adjustment
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Throttle cable adjustment
I happened to look down into the throat of my Q-jet to check the butterflies and noticed that the rear butterflies wern't opening all the way. I'm using the stock cable and mounting brackets and cant see anyway to adjust the cable except to slide it back at the bracket clip and then tighten it down. Is it required that the small ridge on the metal band of the cable be held up against the clip? Thats what I have now and the rears dont open all the way.
Thanks
Thanks
Melting Slicks
Joined: Oct 2010
Posts: 2,276
Likes: 337
From: "ɹǝpunuʍop", Adelaide, South Australia
not sure on your year, but,
check for any floor mats under the accelerator pedal are causing the limited travel.
or if the pedal lever/arm is bent after many year of pressure.
check for any floor mats under the accelerator pedal are causing the limited travel.
or if the pedal lever/arm is bent after many year of pressure.
Race Director
Joined: Nov 2006
Posts: 13,227
Likes: 7,825
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
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Cruise-In VIII Veteran
If the front butterflies open all the way the issue is NOT in your cable. Don't care what year it is.
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
From my Q-Jet Setup paper:
A common problem is the issue of inadequate throttle cable travel. This is very common on Corvettes and Camaros. With a helper in the car and with the engine “off,” have the helper fully depress the gas pedal (with the engine hot and the choke wide open to assure that the lockout lever is disengaged). Observe the carb on the driver’s side and see if the secondary throttle moves to the wide open position: You can grab the throttle lever once the assistant has the pedal to the floor and see if you can move it further. If the gas pedal does not fully open the secondary throttle, you have one of several methods to fix this:
Lars
A common problem is the issue of inadequate throttle cable travel. This is very common on Corvettes and Camaros. With a helper in the car and with the engine “off,” have the helper fully depress the gas pedal (with the engine hot and the choke wide open to assure that the lockout lever is disengaged). Observe the carb on the driver’s side and see if the secondary throttle moves to the wide open position: You can grab the throttle lever once the assistant has the pedal to the floor and see if you can move it further. If the gas pedal does not fully open the secondary throttle, you have one of several methods to fix this:
-
- Remove your floor mat. I call this the “25 horsepower floor mat tuning trick.”
- Install the throttle cable in the correct position on the throttle lever. The Q-Jet has an “upper” and a “lower” cable attach hole: The upper hole was used for trucks and station wagons. The lower hole was used for Corvettes, Camaros and Novas. If you install a Corvette throttle cable in the upper hole, you will never achieve wide open throttle since there is not enough cable travel to open the throttle from the top lever location.
- Straighten your throttle cable attach bracket. The bracket that supports the cable at the carb is often bent slightly forward. If the bracket is bent or moved forward, it will not allow enough cable travel to open the throttle fully. Simply bend the bracket back just a tad: I use a big hammer and a steel rod to give it a whack. I call this the “25 horsepower hammer tuning trick.”
- Fix your gas pedal linkage. Very often, the actual steel linkage coming off your gas pedal will be bent a little “flat.” This will cause the pedal to hit the floor before the carb is wide open. You can give the pedal more travel by simply grabbing the gas pedal and bending it up off the floor. Care should be taken not to damage any plastic pedal rod bushings when doing this: Support the plastic pivot points when bending the pedal rod so the plastic bushings do not break.
- Fix the slop in the gas pedal attach lever. Many C3 Corvettes have a bit of wear on the lever that attaches to the gas pedal rod: The rod is "D" shaped, and the attach lever has a "D" hole with a screw tightening feature. If this "D" hole is worn, you can remove the lever, grind some material off the locking feature surfaces so it snugs up tighter, and re-install it to gain some travel.
Lars
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Thanks Lars
I'm still dialing things in. Got the little vac adv limiter you sent me in, and thats working as it should. Just picked up a spring kit for the dizzy and will change those tommorow. Ive got the 36* set but it doesnt come all in untill about 3700, so the spring change should do the trick.
So far every little bit of work is bringing good results. I will chase the cable problem and get that squared away.
Thanks for all the help
Dan
I'm still dialing things in. Got the little vac adv limiter you sent me in, and thats working as it should. Just picked up a spring kit for the dizzy and will change those tommorow. Ive got the 36* set but it doesnt come all in untill about 3700, so the spring change should do the trick.
So far every little bit of work is bringing good results. I will chase the cable problem and get that squared away.
Thanks for all the help
Dan
