Reinstalling Quadrajet- getting it to run right

[Chanman09]

Hello all,

I have just finished rebuilding my first carburetor!

Rochester Quadrajet.

I will say, I’ve put this off because it’s looked scary, but just like electrical work in the past, I got on here and snooped around enough, watched hours of YouTube videos and read manuals both hard copies and pdfs and cinched my belt up and did it.

I will say that the rebuild went smoothly and wasn’t nearly as daunting as I thought it would be. I will admit I didn’t get too carried away and just basically cleaned all the old gas and gunk out. Lots of elbow grease and chemicals and I feel like a very clean finished product was presented. I did not take out restrictors or cups or any super tiny pieces and just made sure they were clean and clear of obstructions.

I reinstalled the thing the other day and got the truck (1986 C20- 350/350) to start but it died quickly.

A few tubes of main screws up front and realizing my choke wasn’t set correctly I managed to keep the truck running for a little bit. And it was pretty smoothe compared to before the cleaning.

Here’s my question:

How do I dial it in where I can just turn the truck on? Lol.

Big question I guess.

I’m not sure I have any setting correct and I’m just out there blindly trying. I don’t really have anyone to help that would know about carburetors (or cars at all really) that could come stop by.

I’m currently looking at the Haynes charts on my specific carb but don’t know what it means. It’s like Greek.


I snooped on here and saw lots of quafrajet questions, but they seems specific to already running and just maximizing performance. Also,  I may have missed something obvious in the read only sections. So sorry if I did.

Thanks for any help yall can send my way!

[VileZambonie]

Assuming you have no vacuum leaks, and everything is hooked up correctly, is the choke working? Are you adjusting the fast idle speed screw? Off of the fast idle cam, are you adjusting the idle speed screw? Does it run if you give it throttle?

[Chanman09]

Vacuum ports are all accounted for or plugged, with the exception of the small port that goes to the breather nozzle thing.

My choke was floppy and the flap stayed open until I adjusted the choke element. Now it starts closed and has a spring to it when pushed open. The truck hasn’t ran long enough to warm up to see if it opens by itself. The vacuum thingy near choke operates when I manually checked it with thumb over the end of the port.

I had to back the main screws up front back several half turns to get it this good even. So I’m pretty sure they wereentnletting air/fuel in. They still may need to be unscrewed some?  Maybe 3 turns out so far.

Idle speed screw? Not touched it. Fast idle cam screw? Haven’t touched it.   The screw under the choke element and the screw under the throttle linkage is what you mean??  I haven’t touched them. But they may have been wrong to begin with. (Field find sitting since 96)

It runs if I give gas. I let off and it dies within 3-5 seconds.

[JohnnyPopper]

Get it warmed up to OT before adjusting. Operating Temperature for those who drive Fords.   

[zucchi]

To begin with, if you don't already have these two books that are essential reading, you should get them;  How to Rebuild and Modify Rochester Quadrajet Carburetors by Cliff Ruggles and Rochester Carburetors by Doug Roe (and Bill Fisher).

Tools that will help you greatly are a vacuum gauge, tachometer and a handheld vacuum pump.

Bear in mind that carburation works on air flow and vacuum. ANY vacuum leak anywhere will adversely affect carburetor function and make proper adjustments impossible.