We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re exploring possible causes for leak downs in Quadrajet carburetors.
S.O. • Round O, SC
Q: I have seen numerous Rochester Quadrajet carburetors that have a leak down problem when the car sits idle for a day or more. My question is, how is the gas getting out of the float bowl, and how do you fix it? I have this problem with the Q-Jets on my 1972 Electra and 1986 Chevy pickup.
A: There are two things that can cause a Quadrajet to leak. First, check the two plugs in the bottom of the float bowl. These have a habit of coming loose, which will let fuel in the float bowl drain into the intake manifold.
The second thing is the fuel inlet. Since it sits at the bottom of the float bowl, fuel has a tendency to drain back through the fuel system to the fuel tank.
Solutions? Make sure those plugs are tight and replace the carburetor’s fuel filter with one that has a check valve at the inlet end. This valve will keep the fuel where it belongs—in the carburetor.
[…] for the carburetor, many people consider the Quadrajet to be among the best four barrel carburetors ever designed but the Q-jet is often criticized by […]
my secondary’s are not opening at all on my 69 corvette , I have a rebuilt quadrajet, is it a linkage problem or a vacuum problem. worked great and stopped suddenly.
On the choke side of carb.,there is a lock out pin on the throttle shaft of the secondaries. The choke linkage will lock out secondaries until it warms up. If the linkage is in a bind, the secondaries will remain locked out.
Hope this helps.