Running 2 barrel carb?
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
Running 2 barrel carb?
About 3 weeks ago I tied off the Quadrajet secondaries to work of the primaries without them interfering. I forget about it until today when I took it for a nice long ride.
Is there a downside to not running the secondaries? The car sure runs good.
Is there a downside to not running the secondaries? The car sure runs good.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
If you're only driving on the primaries, there is no difference - the secondaries only open going into WOT. But if you can't tell the difference in performance with or without the secondaries locked out, you have a throttle travel problem that is preventing secondary operation: Have someone press the pedal to the floor while you observe throttle arm movement. With the pedal to the floor, see if the throttle can then be moved further open by hand to open the secondaries. Most C3 Vettes never get the secondaries fully open due to travel problems. You can fix this by:
1. Install the trottle cable in the lowest hole in the throttle arm.
2. Grab the gas pedal and bend it upwards to provide more travel.
3. Remove your floor mat.
1. Install the trottle cable in the lowest hole in the throttle arm.
2. Grab the gas pedal and bend it upwards to provide more travel.
3. Remove your floor mat.
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
If you're only driving on the primaries, there is no difference - the secondaries only open going into WOT. But if you can't tell the difference in performance with or without the secondaries locked out, you have a throttle travel problem that is preventing secondary operation: Have someone press the pedal to the floor while you observe throttle arm movement. With the pedal to the floor, see if the throttle can then be moved further open by hand to open the secondaries. Most C3 Vettes never get the secondaries fully open due to travel problems. You can fix this by:
1. Install the trottle cable in the lowest hole in the throttle arm.
2. Grab the gas pedal and bend it upwards to provide more travel.
3. Remove your floor mat.
1. Install the trottle cable in the lowest hole in the throttle arm.
2. Grab the gas pedal and bend it upwards to provide more travel.
3. Remove your floor mat.
If there is no fuel being used by the secondaries when the linkage is disabled then I may leave it that way. I have a tendency to drive with my foot too far on the gas and I'm getting only 12 or 13 mpg - maybe this will help.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Actually what I was looking for is some info on whether there is any idle circuit in the secondaries and are the secondary throttle plates set slightly open as on a Holley.
If there is no fuel being used by the secondaries when the linkage is disabled then I may leave it that way. I have a tendency to drive with my foot too far on the gas and I'm getting only 12 or 13 mpg - maybe this will help.
If there is no fuel being used by the secondaries when the linkage is disabled then I may leave it that way. I have a tendency to drive with my foot too far on the gas and I'm getting only 12 or 13 mpg - maybe this will help.
I suggest going to a DPFI unit for economy and performance, but i'ts a techy effort, and some money spent...the aftermarket units are WAY more expensive than say an old TPI unit....long time to make up for 2-3 grand worth of update gear....but 5-700 is more doo able....
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Actually what I was looking for is some info on whether there is any idle circuit in the secondaries and are the secondary throttle plates set slightly open as on a Holley.
If there is no fuel being used by the secondaries when the linkage is disabled then I may leave it that way. I have a tendency to drive with my foot too far on the gas and I'm getting only 12 or 13 mpg - maybe this will help.
If there is no fuel being used by the secondaries when the linkage is disabled then I may leave it that way. I have a tendency to drive with my foot too far on the gas and I'm getting only 12 or 13 mpg - maybe this will help.
There is no way you can drive the car at cruise using the secondaries. The secondaries start opening at about 3/4 throttle travel, which basically means you'd have to have the pedal to the floor before you're into the secondaries on a Q-Jet.
