Q-jets

[1969K10]

Are there differences in Q-jets that make some more desireable than others? I've got the one I'm running from a '79 camaro, and one on the shelf that I was on my truck when I bought it. I'm going to need to do a carb rebuild, and wondered if it was worth messing with the shelf one to see if it was any different than the one I'm running... I'm not really looking to go huge CFM, just easier to work with really.
THX

[jacobs]

See http://www.corvetteclub.org.uk/files...une_a_qjet.pdf

[Zoomad75]

Get the book "rochester Carburators". In the book it breaks down what carbs were which size, what's able to be tuned or not tuned.

Personally I'd shoot for late 60's to early 70's car versions or up to late 70's trucks. Reason being is once the pollution controls were getting more strict, they started putting limiting caps or block off plugs to the idle adjustments. Even later ones had the goofy mixture control solonoid for the computer controlled q-jet.

The early ones are completely adjustable. Plus with the book you can break down the fuzzy logic to q-jet tuning with actual sizes for rod's jets and hanger. It's worth the price.

[1969K10]

Jacobs - the link is dead, but it got me close enough to find some Q-jet articles to read & one of them breaks down the Q-jet #'s - THX

Zoom - thanks! I'll be digging that book up and seeing what's in it!

[jacobs]

Originally Posted by jacobs

See http://www.corvetteclub.org.uk/files...une_a_qjet.pdf

Try this http://www.corvetteclub.org.uk/files...une_a_qjet.pdf

OR http://www.vetteclub.org/TechnicalTi...ng%20Paper.pdf

You may want to stay away from the 1965 to 1967 q-jets. They had a diaphragm type fuel-inlet valve instead of the normal needle-and-seat.
I have one I purchased new in 1966 and I've never had any problems with it but many don't like them.

[DieselEater]

I have read Cliff Ruggles Book more than a dozen times, and have learned something new every time!!! Although the Q-jet is fairly complicated to dial in on a specific engine combo, I think it is the best choice carb up to 700 H.P.!!!!!! Learn it!!! Buy the book, along with a hand full of carbs at 5-bucks each, along with a couple good rebuild kits and learn...........Look up Lars Grimsrud's papers on tuning q-jets also..........

If you don't want to go deep into learning q-jets, but still want one......Buy an Edelbrock 1910 850 cfm.........worth it!!! (still have to tune it though).

[jacobs]

Not to hyjack the thread but is Cliff Ruggles book better than Doug Roe's book on Q-Jets? I always thought Doug Roe's book was excellant but maybe I ought to expand my library.

[DieselEater]

I would answer by saying the same thing you just said!!!! I'll look up the one not read to see if anything is better or worse.........


Anyway, I have a date with LARS GRIMSRUD this spring to get my JET Q-JET from JEGS dialed in for my specific application. Again.........If you are not making more than 700 HP....I think a Q-Jet is the way to go!!!! But you will have to learn them and rebuild a lot of them and cuss a-lot and etc.....

My biggest reason for saying all of this is using a Holley 750.....a badly tuned Q-Jet.....and a edelbrock square bore. The feeling at 6000 RPM with the Q-Jet was nothing short of spectacular (spelling). Great response in the primaries due to small size. AWESOME WOT if tuned due to HUGE secondaries.......BEST CARB EVER MADE.........!!!!!!!!!!!!!

[jacobs]

Originally Posted by DieselEater

Anyway, I have a date with LARS GRIMSRUD this spring to get my JET Q-JET from JEGS dialed in for my specific application.

Any idea what Lars charges?

[DieselEater]

Not a clue??????!!!!

In an e-mail he replied to my request after multiple correspondence to call him when I was ready for my test and tune. I fully plan on taking care of him based on the idea that he answered my questions and said come on up. (Let alone he actually knows what he's doing!!) I'd gladly pay him more than expected due to the fact that he appears to be an actual nice guy and not an arrogant (spelling) dude who wants to make money!........I'll definitely report my findings to all after we get down to business. Just remember, I'm building a purpose based Pullin' carb for MAX flow @ 7500 RPM!!!!! This carb may not work for a street/strip Chevelle?!?!

I'm on this site PURELY DUE TO THE FACT THAT CHEVY BOYS SUPPORT CHEVY BOYS!!!!!!!!! (I love my favorite Truck Pullin' site; But, they do lean toward the F-WORD).

http://www.network54.com/Forum/228279/

Very Cool Guys Here!!!!!!!!!!!!

Thanks,

A..............

[jake60]

Originally Posted by DieselEater

Anyway, I have a date with LARS GRIMSRUD this spring to get my JET Q-JET from JEGS dialed in for my specific application. Again.........If you are not making more than 700 HP....I think a Q-Jet is the way to go!!!! But you will have to learn them and rebuild a lot of them and cuss a-lot and etc.....

My biggest reason for saying all of this is using a Holley 750.....a badly tuned Q-Jet.....and a edelbrock square bore. The feeling at 6000 RPM with the Q-Jet was nothing short of spectacular (spelling). Great response in the primaries due to small size. AWESOME WOT if tuned due to HUGE secondaries.......BEST CARB EVER MADE.........!!!!!!!!!!!!!

Any updates??????

[eedgell]

If I remember right some Q's were made by carter, I think, and they are aluminum, Not as desirable. There rebuild kits are a little different as well. The rochester Q's are magnesium, and a much tougher body. Just a thought. They are casted with the maker on the body. Pretty easy to tell if you just look.