General Category > Quadrajet Carb Talk and Tips
Airhorn vent
mcx:
Cliff...what was the last year the qjet used the airhorn rubber vent at the front of the carb,
which has small linkage attached to accel pump arm? I have a 7042211 which has this feature but I feel it might be a mismatch of parts. Thx, Mike
Cliff Ruggles:
It was not used in 1972 and started to disappear by the end of the 1969 production run.
You'll find it on some 1970 models but can't say I've seen anything 1971 or later that used it outside of a few Service Replacement carbs.
I'll add here that the 1972 airhorn also used the large MAB's and most of the vented ones used much smaller MAB's so for sure it would not work well without recalibration if they are still in place.......Cliff
mcx:
Thank you for the info, I cross checked a 7042210 and it has .120" mains and sure enough this mismatch 7042211 has the much smaller bushing type main bleeds...I even rechecked a 7045229(1975 Chevy) and it has the huge mains in her, like you are saying.
...could the 7042211 Mains just be carefully drilled to match .120" and call it a day? Mike
mcx:
I was looking at the two airhorns , it seems the only other difference between the pre 70 rubber vent type lid with the small bushed type main bleed and the later post 70 non rubber version with the larger main bleeds is the air path through the airhorn idle air bypass...a pre 70 airhorn to main body gasket would be needed for it function,correct? Drill out the main to .120"and swap out to correct gasket?
Cliff Ruggles:
I would not drill out the MAB's without knowing what else has been done to the carb?
It may be a "reman", or other parts swapped in conjunction with the incorrect top.
If the airhorn isn't "notched" for bypass air the notches can be added. Far better than trying to use a notched gasket as they will often "whistle" with airhorns that aren't notched as the air passes thru the small flat openings......Cliff
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