Carburetor Adjustment Guides/Articles

[T.Wagner]

Hi All,

I am looking for some links to how carburetors work and how to adjust them. Specifically for the Rochester Quadrajet on my '83 Hurst. I want to learn more about them and in my own research I am not finding much pertaining to car carburetors. I am waiting to get my service manual which will likely have some information in there, but I am looking for some more in-depth articles. Mainly the more tedious adjustments like jets, float levels, and metering rods. I would love to be able to adjust it myself and really get the carb running the best that it can!

Thanks for your help!

 

[G-Body_Vet]

There's a few good books on q-jets. One by Doug Roe, the other by Cliff Ruggles.

Here's a site too.
http://cliffshighperformance.com/simplemachinesforum/

 

[drogg1]

I thorouhly enjoyed Cliff Ruggles' book. It gives a complete run down of the function of each part. Additionally, it explains how to start tuning from idle to full throttle. He gives a few examples of different jet sizing and setups for different levels of performance and use. Which carbs came in which cars and which are the more desirable is explained. Definitely knowledge above and beyond what you might easily or immediately find online and backed up by years of experience.

I've also heard that Doug Roe's book is execellent.

 

[pontiacgp]

Cliff Ruggles book is great and the best tool I have bought to tweak the quadrajet is a wide band air/fuel mixture gauge. It takes the guesswork out of the equation to do the final settings for the engine it is on

 

[T.Wagner]

Thanks for the recommendations!

Cliff Ruggles book is great and the best tool I have bought to tweak the quadrajet is a wide band air/fuel mixture gauge. It takes the guesswork out of the equation to do the final settings for the engine it is on

I saw a post you made about that wide band air/fuel mixture gauge! It looks like a great tool and I am definitely interested in it. We have been taking my car to a mechanic that we like and he does a pretty good job, but I really want to learn to do everything myself. He has my carb set-up pretty good right now (and it was just rebuilt a month ago) but I am sure if I learned how to do it and had the necessary tools I could get the car running to its highest potential.

The only thing that I am nervous about is adjusting all the internals like metering rods, float levels, and jets. I'd be afraid to screw it up... I looked quick online and it seems the metering rods are pretty expensive! I am a little scared for the trial and error process because it looks like that will add up really quick...

Also, does it matter that my carb is computer controlled? At least I think it is since it has electrical plugs and sensors on it. If I go changing things like jets and metering rods will that screw up the way the computer senses things?

 

[T.Wagner]

pontiacgp, how is your car running after you got that gauge? I believe in the thread you made about the wide band you said you feel it increased performance and it should get an extra 2-3 mpg on the highway? I didn't see any updates after that.

 

[pontiacgp]

It's running better than ever but any fuel savings have been deleted by my right foot. I am going to try a new set of primary rods this week cause it's running a bit lean at cruise on the highway. To compensate that I have my idle mixture a bit rich. If not for the gauge the car is running so good I would not have known that the carb could use a little tweak.

 

[T.Wagner]

It's running better than ever but any fuel savings have been deleted by my right foot. I am going to try a new set of primary rods this week cause it's running a bit lean at cruise on the highway. To compensate that I have my idle mixture a bit rich. If not for the gauge the car is running so good I would not have known that the carb could use a little tweak.

Very cool! I want to get me one someday. What kind do you have?

Right now I am just working on getting everything set-up with the vacuum system. I'm going to go through it all over the next few days/weeks to make sure everything is routed to the correct location. After that I may start tweaking the carb!

I also found a YouTube video where the guy explains re-jetting his Quadrajet. I thought the video was pretty good and informative so I'm posting it here in case anyone is curious.

Part 1:

Part 2:

 

[pontiacgp]

That guy is a member here, I posted those videos on another thread but it deserves repetition...he's known in this forum as edonthebeach and those videos are really well made and informative..

 

[T.Wagner]

Before I decide to start tinkering with the carb is this even something I can do? I assume that once they became computer controlled you can't really adjust them that much? All I know is I have the 4MV on my '83 Hurst/Olds and I see some electrical switches on the carb. Can I change the metering rods/jets in my carb or is that going to screw up everything?

This seems like a good little kit if I actually decide to go through with tweaking it.
http://quadrajetparts.com/quadrajet-calibration-tuning-1975-later-jets-p-301.html