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Old 10-25-2004, 06:20 PM
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Rebuilding a QJet for high performance - what year?

I'm looking to rebuild and modify a QJet to deliver top performance for my Vette. I was looking at ebay and wondering what year should I go for?

Also, is a QJet from a Camaro, Corvette, Chevelle, etc. any different from the other ones of that year? See what I mean?

Ideas/suggestions?

Thanks!
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Old 10-25-2004, 06:47 PM
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Why not just order a Q-jet to your specs from Sean Murphy Induction or Jet performance? both companies will set the carb up to match your engine specs. Q-jets came on low to mid performance vehicles, in the late 60`s high performance cars came with Holley carbs. The Q-jet changed over the years, and each one`s calibration (metering rods and hangers) were different per engine. any of them can be made to work in a performance application, but I wouldn`t bother with the feedback Q-jet of the early to mid 80`s.
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Old 10-25-2004, 06:49 PM
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Q-jets

If you can get one use the 69-70 years. Chevy & Pontiac had some really strong engines then being fed by the Q-jet. But I think you will have to stick to something off a chevy engine though. Our 70 Vette with a 350/300 horse engine takes the fuel inlet on the side but our 70 Pontiac 455 takes the fuel inlet straight on.
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Old 10-25-2004, 06:54 PM
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Re: Q-jets

Quote:
Originally posted by Restore60s
If you can get one use the 69-70 years. Chevy & Pontiac had some really strong engines then being fed by the Q-jet. But I think you will have to stick to something off a chevy engine though. Our 70 Vette with a 350/300 horse engine takes the fuel inlet on the side but our 70 Pontiac 455 takes the fuel inlet straight on.
And a 69 - 70 will bolt on to my 350 SBC? Shouldn't be any problems? Also, if I see one for a BBC, is it still compatible? Or do I have to stick to 350, 327, 305, etc. SBCs?

Thanks!
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Old 10-25-2004, 06:59 PM
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The Q-jet bolt pattern never changed. Rather or not it`ll bolt up to your engine depends on what intake your using, as some have a square bore pattern and others have a dual pattern that will accept spread and square bore patterns.
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Old 10-25-2004, 07:04 PM
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So if I have a QJet on my Vette right now with the stock intake manifold, any QJet from any year will bolt right up? So it has nothing to do with compatibility then.
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Old 10-25-2004, 07:10 PM
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if your using the stock intake yes any Q-jet will bolt up. Is your engine performance or stock? keep in mind if you just pick up a Q-jet and rebuild it, it won`t be calibrated for your engine and performance will suffer. Any carb has to be calibrated, Q-jets were installed on millions of GM vehicles, from 6 cylinders to 500 cubic inch caddy`s, if you took a Q-jet off a 305 chevy and stuck it on a 500 caddy it would be so lean it would likely cook a piston or some valves. Keep this in mind when you go Q-jet shopping.
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Old 10-25-2004, 07:19 PM
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Well I have an L48 350 ci SBC. Can I get away with a '70s 350 or a '69 327?
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Old 10-25-2004, 07:56 PM
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Q-jets

You guys are wearing me out I had to go fight the spiders to dig out my 70 Vette service manual.
Okay in 69 the Vette used a Rochester 4mv on the 350/350 HP engines and the 427/390 HP engines.
The 350 used a 0.066 main metering jet while the 427 used a 0.071 main jet. Both had a Primary Bore of 1-3/8 " & Secondary Bore of 2-1/4 "
In 1970 the 350/300 HP & 350 HP engines used the same 4mv q-jet with a Main jet size of 0.076. And the bore was a Primary-1-3/8 & Secondary Bore of 2-1/4". Holley's fed the BB engines in 70.
The 70 & the 69 427 q-jets used a 1/4 float level while the 69 350 used a 3/16th float level.
Mid 1972 is where you see a big drop on corvette engines power & carb jetting small block or big block.
Hope this sheds some light.
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Old 10-26-2004, 05:01 AM
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So what do you suggest for my application and Corvette then? A '69 for the 350?
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Old 10-26-2004, 06:33 AM
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Q-jets

I think either year 69 or 70 should provide you with what you need for fuel delivery. What I like about the Q-jets of those years is they were built for performance engines and were very dependable. So if you find one all is really needed is a good rebuild.
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Old 10-26-2004, 06:53 AM
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I'm not just looking for rebuild and reliability, but I have performance midifcation for the carb in mind as well.
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Old 10-26-2004, 07:01 AM
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q-jets

Those q-jets would be the perfect base to start at. Your headed in the right direction. Good Luck!
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Old 10-26-2004, 11:15 AM
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I was just looking at a couple of adds on ebay and this is one description:
Quote:
1969 Chevrolet Corvette 4-barrel Quadrajet(7029202) carburetor for 350 cu.in. automatic transmission car. It is also correct for 1969 Camaro,Chevelle,ElCamino and Nova.
What does the tranny have to do with the carb??
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Old 10-26-2004, 01:20 PM
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Tranny

[size=3]Doc here

The tranny has do do with a vacuum port on the base of the Q~jet at the rear of the throttle body for attaching the modulator valve line.If yours in manual, you can attach the Brake booster here Although The Manifold is the best source for that.

ANY Q jet, 1979 and down will be a good base to start (or even just bolt straight up) for your Corvette.

1979 and above had the TPS (Throttle positioning solenoid) and Throttle metering solenoid , located on the Front left and right of the airhorn, with a plug for each. these are used for Computer data. While you can Bypass these, or remove them, you just don't need them...so If your shopping EBAY, avoid them.

Q~jets came in a Couple of flavors Too I think prior to 81...650 CFM and 750 CFM...I think if your running a Stock 350, The 650 is the Best choice for that engine. 750 might dump more fuel then it's willing to digest.

Try to find one with an Electric Choke, and a anti~diesel valve (big solenoid on the throttle return) You'll be glad you did.

If you Build one right, tune it correctly, and maintain it well, a Q~jet can deliver good Street Kick, and still retain some semblance of Economy...(10 to 12 hwy on a Vette depending on how you drive it) My 80 gets 10 (on a fresh rebuild), My 2- 78's get between 6 and 10 (older carbs, that could use cleaning)

If you buy off EBAY, Expect to rebuild it...No matter what the seller tells you...Then if it shows up, and is rebuilt clean and correct...it's a plus!

AND A WORD TO THE WISE:

Don't Bid on ANY parts from seller: MELMYRA... She deals in Vette parts, and is a thief!!

She will sell you an Item, and when your check clears...Re~list it and sell it to someone else! (I followed her listings AFTER the items I bid on didn't show up!)

Then when you Complain, she'll tell you "It's lost in the mail!!" Sorry no refunds!(and since these were Several small items from different bids, I didn't bother to insure them...big mistake!)

I contacted The postmaster in her Hometown (small burg, that the P.M. personally knew everyone) and SHE said, She hardly mails stuff at all...and none to my address...They were put on alert for mail fraud...

I also contacted EBAY...and despite their policies, Other than negative feedback.. unless you buy EBAY insurance your on your own...Then I believe they only pay like 10% the bid price..

I bid on,. and won bids under several different Screen names, many items , Several hundreds of dollars...NONE of it ever showed up on my doorstep From HER!!

Good Luck with it!

Doc
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