Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: spoolboy on March 28, 2025, 08:46:58 AM

Title: Make the bypass air easily adjustable
Post by: spoolboy on March 28, 2025, 08:46:58 AM

Is there a way to make the bypass air system easily adjustable via some sort of jets or a screw?

It would be cool to not have to move the throttle plates and uncover the transfer slots to adjust idle speed.

Title: Re: Make the bypass air easily adjustable
Post by: Kenth on March 28, 2025, 10:20:32 AM

Some Quadrajet do not show the transfer slots at idle, like 1972-74 Pontiac Qjets.
Other will show the transfer slots with throttle blades fully closed, like some Chevy M4 units.

Not a big deal, if you need to open the throttle blades more than 1.5 turns on the idle speed screw, add som idle bypass air in small steps accordingly.
You may need to add idle fuel to have control of the idle mixture needles.

HTH

Title: Re: Make the bypass air easily adjustable
Post by: Cliff Ruggles on April 06, 2025, 06:20:00 AM

You can tap the baseplate for removable brass set-screws if you want an easy way to add or take away idle bypass air.  I seldom do this, unless it's a pretty "high end" full race build that I may have to go back into for fine tuning once it's placed in service.  For those builds I also install removable DCR's and idle tubes, but for sure that's "overkill" for most of these builds......