Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: 65malibu on July 06, 2024, 07:18:57 AM

Title: 17084223 idle bypass air
Post by: 65malibu on July 06, 2024, 07:18:57 AM

What is the correct way to size the bypass air? I have control with the mixture screws, but if I pull off the hose to the choke pull-off the idle speeds up, seemingly needing more air. Should I go up in size of the bypass until the idle doesn't increase?

Title: Re: 17084223 idle bypass air
Post by: 77cruiser on July 06, 2024, 08:58:54 AM

No, if it idles & drives good & no nozzle drip I'd leave it.

Title: Re: 17084223 idle bypass air
Post by: quadrajam on July 07, 2024, 06:49:20 AM

^X2

Title: Re: 17084223 idle bypass air
Post by: Cliff Ruggles on July 08, 2024, 01:19:27 AM

Pulling off a small vacuum hose should increase engine speed.  Lower the idle speed back down and re-adjust the idle mixture screws, if needed, and see if it improves sensitivity with them and no nozzle drip.  In most cases no need to add more bypass air if you don't have nozzle drip and full control with the mixture screws, but every application is slightly different and there are times when adding a little bit more helps.....

Title: Re: 17084223 idle bypass air
Post by: 65malibu on July 08, 2024, 07:53:31 AM

So, readjust the mixture screws and idle with the small vacuum hose off? Wouldn't it be rich when I put the hose back on?

Title: Re: 17084223 idle bypass air
Post by: Cliff Ruggles on August 16, 2024, 03:44:49 AM

If it likes that scenario then you can go in and open up the idle bypass holes in the baseplate to duplicate it.  Of course you will need to put the hose back in place for testing.....