Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Idle problem pontiac HO 7237262

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Ethan1:
 

Ethan1:
 The photo I posted above, I believe this is what Omaha is referring to. The Idle Air Bypass. They are located just above the white circles. One is straight and the other looks like a dog-leg.

Cliff Ruggles:
The 1967 Pontiac carburetors didn't have idle bypass air, and it will most likely need some for that cam in a 400 application.  It can be added to the baseplate, and main body/airhorn modded as needed, or you can try drilling two very small holes in the throttle plates directly in line with the mixture screw holes, about 1/4" back on the throttle plates.  This will help, but it is not as accurate as using idle bypass air (controlled vacuum leak).

The carb will also need larger idle tubes, and idle down channel restrictions opened up some for that application.  Do you have one of our books?....Cliff

Kilraine hoGTO:
Throttle plates already have small holes in them , looks like factory ..., I dint want to "booger" up the casting , so if possible would like to send to you for mods ,, thank you all for great responses .. They all make sense...

Cliff Ruggles:
Probably a good idea for that one.  The early carbs don't use idle bypass air, and that carb needs some for the XE274 cam in a 400 application.  Needs a LOT more idle fuel as well.

If it were mine I'd put a different cam in it, and it would NOT be a Comp XE grind......Cliff

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