Why is it doing this
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,235
Likes: 1
From: Sterling Va
Why is it doing this
On a 79 Corvette when you floor it you can hear that 4 barrel sound but it's quiet, and for about 2-3 seconds the car feels like it's not running at all just coasting, then it finally takes off. Just had a major tune up (timing, plugs, wires, cap, rotor). Car had been sitting awhile but now has fresh gas.
Melting Slicks
Joined: Jun 2001
Posts: 2,264
Likes: 546
Most likely the secondary spring is not tight enough causing the secondaries to come in too quick. On the seconday air valve shaft (passenger side) there is a allen wrench set screw, coming up from the bottom. Loosen the set screw and adjust the air valve till it just bearly closes then turn the wind up spring 3/4 to 7/8 turn and lock the set screw. DO NOT turn more than one turn it will distort the spring. 
Ron B.
Ron B.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by itsonlyairandfuel
Most likely the secondary spring is not tight enough causing the secondaries to come in too quick. On the seconday air valve shaft (passenger side) there is a allen wrench set screw, coming up from the bottom. Loosen the set screw and adjust the air valve till it just bearly closes then turn the wind up spring 3/4 to 7/8 turn and lock the set screw. DO NOT turn more than one turn it will distort the spring. Ron B.
Ron B.
I would add-when you loosen the set screw the other screw will all of a sudden spring and you will loose the original setting-find a picture-in the end of carb is a straight blade screw-hold it while loosening set screw-then tighten it 1/4 turn then tighten set screw and go roadtest-adjust again as nec.
Last edited by ...Roger...; Sep 28, 2006 at 09:15 AM.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
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From: Dayton Oh
Originally Posted by Ibuyvettes
On a 79 Corvette when you floor it you can hear that 4 barrel sound but it's quiet, and for about 2-3 seconds the car feels like it's not running at all just coasting, then it finally takes off. Just had a major tune up (timing, plugs, wires, cap, rotor). Car had been sitting awhile but now has fresh gas.
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Drifting
Joined: Jul 2002
Posts: 1,995
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From: Garland Texas
Check the choke pull-off. It controls the opening rate of the air valve. Also you have two fuel pick-up tubes insde the carb and two booster tubes for inital secondary operation. It is very common for 1 or more of these tubes to fall out of top plate and into the float bowl. Since the car finally does start to pull there's a good chance you dropped a booster tube.
Mike
Mike
Intermediate
Joined: Aug 2006
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From: Lynn Ma.
Originally Posted by paul67
I would vote for the accelerator pump. Test as noted above. Adjustment is by bending the rod. Rather crude but it works.
Russ
CF Community Team
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From: Cape Cod, Mass.
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3rd vote here for the accellerator pump. I agree that there should be no lag on a properly set up Quadrajet.
Racer
Joined: Feb 2004
Posts: 360
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From: Meridian, MS
Originally Posted by Ibuyvettes
I don't know where all these parts are, I need layman descriptions.
Race Director
Joined: Feb 2005
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Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Originally Posted by DWncchs
Ibuy is that flooring it from a standing start or flooring it while cruising?One is a primary problem and one is a secondary problem.
Mike
