Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: ChevyZ06 on November 13, 2018, 01:05:10 PM

Title: Idle Air Bypass
Post by: ChevyZ06 on November 13, 2018, 01:05:10 PM

I am working on a 1969 Q-jet on a 454.  I am trying to increase the air around the throttle plate and keep the correct angle. I have located the ports in the base plate and the body but I am not sure exactly where they are restricted in the top. Does any have a picture of the IAB restrictions?  Thanks

Title: Re: Idle Air Bypass
Post by: 77cruiser on November 13, 2018, 03:10:23 PM

How big are the ports in the base? That's where the restriction is.

Title: Re: Idle Air Bypass
Post by: ChevyZ06 on November 13, 2018, 03:20:22 PM

I will have to check. From memory I think .080

Title: Re: Idle Air Bypass
Post by: ChevyZ06 on November 15, 2018, 11:29:08 AM

Guys please take a look at this video and tell me if you think that this can be caused by anything other than what I think it is. Thank you

https://www.youtube.com/watch?v=GYZPl4_2_z0

Title: Re: Idle Air Bypass
Post by: Cliff Ruggles on November 16, 2018, 02:57:00 AM

What is the carburetor number?

Why do you think it needs more idle bypass air?

Nozzle drip at idle?

Control with the idle mixture screws?

Title: Re: Idle Air Bypass
Post by: ChevyZ06 on November 16, 2018, 10:02:23 AM

7029207...  Its on a 454 and I am having idle problems.  Cover the air horn and the idle gets better.  Ithink my throttle is open too far.

Title: Re: Idle Air Bypass
Post by: Cliff Ruggles on November 17, 2018, 05:10:12 AM

It's probably a Service Replacement 7029207 and they were set-up/calibrated for the 350/350HP manual transmission engines.

They can be effectively used for big block applications, but you will need a few parts and slight modification to the idle system.

When you get time call the shop, we'll need the cam specs, compression of your 454 and can help out from there.......Cliff