Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: stevef on July 28, 2011, 06:51:32 PM

Title: accelerator pump rod...which lever hole to use?
Post by: stevef on July 28, 2011, 06:51:32 PM

I've noticed that on the Trans Ams I've seen with Pontiac q-jets, the rod is hooked on the outer hole of the pump lever. On the TA's with 403 Olds, the rod is hooked to the inner hole location. Why the difference?
Do all Pontiac q-jets use the outer hole?
If not, how do you decide which hole to use? Thanks.

Title: Re: accelerator pump rod...which lever hole to use?
Post by: Cliff Ruggles on July 29, 2011, 03:11:53 AM

The inner hole is preferred unless the application doesn't want or need as much fuel from the accellerator pump.  The length of the pump and the springs used on and under it are also a player here.  For most non stock applications, we use the inner hole.  I've had a few customers with high altitude applications move the arm to the outer hole to reduce some pump shot, but even seeing that done is a pretty rare.....Cliff

Title: Re: accelerator pump rod...which lever hole to use?
Post by: stevef on July 29, 2011, 07:58:17 AM

Thanks for the quick reply Cliff!

Good to know how you usually set it up.

It sounds like it works the opposite of what I was thinking. So, using the outer hole causes less pump shot? With the rod being on the outer hole on the end of the arm further away from the pivot, I would have though you'd get more pump shot.
And using the inner hole, closer to the pivot, provides more pump shot? 

Title: Re: accelerator pump rod...which lever hole to use?
Post by: Cliff Ruggles on July 30, 2011, 04:20:56 AM

Closer to the pivot point provides more movement on the opposite end.  Much like using a higher ratio rocker arm in an engine.....Cliff

Title: Re: accelerator pump rod...which lever hole to use?
Post by: stevef on July 30, 2011, 05:23:00 AM

Thanks alot for the clarification!