I am going to be rebuilding a 350 for my berlinetta, and I have q-jet from a 1970 350 pickup truck. it has no emmissions, which is why i want it, and i have some questions. i plan on rebuilding it, what can i do to get more performance out of it? i want good gas mileage, this is why i like these carbs, but has anyone ever built up a camaro with a q-jet and gotten great results? i would like to be in the 300 hp range. thanks

 

I have used them for well over 15 years now in all sorts of applications. They can easily handle 300 HP. The imprtant thing is to make sure some dip-stick who had the thing before you didn't mess around inside the carb and start ripping stuff out he didn't understand. Like the power piston assembly and primary metering rods. Once you KNOW you are back to stock specs and everything is working correctly THEN you can start tuning for performance.

The secondaries should be the first place you concentrate. Get a good set of performance-oriented metering rods. I am partial to "DR" rods, myself (GM p/n 17053659- still available!). Combine that with a "G" hanger (available from Edlebrock) and you're gonna be in good shape.

Loosen up the secondary air valve tension spring from 7/8 turn stock down to only 1/2 turn and those secondaries will come in much quicker and increase mid-range torque quite a bit.

That's about 75% of the battle right there. There's a LOT more that can be done but tose simple mods will DEFINITELY make a big difference in performance- not jsut on a dyno, but torque you can FEEL when you open it up.

 

thanks a lot, also, this is my first project car, it is a senior project, and I would like to rebuild my own carb. Is this possible or should i take it and have it done with my experience level? thanks

 

If you're going to do it yourself for the first time please go buy yourself a book called Rochester Carburetors by Doug Roe (available from Summit and you local speed shop). There is an EXCELLENT chapter on how to do a basic stock rebuild of a QJet. Also, you can send me an email when you are ready to tackle it and I'll be happy to give you some pointers and work with you to get the jets/rods and other calibration issues "in the ballpark."

It's not at all like a Holley inside and there are VERY few people around who really know them cold (that is to say, I trust MYSELF over any "professional" shop I could send it to!). But in a single rebuild, if you really take the time to understand how the systems work you can be well on your way to being a QJet guru. Knowing how to make 400+ HP with a $20 carb you can buy in any junkyard is a handy skill to have!



[This message has been edited by Damon (edited April 26, 2001).]

 

I have my Q-Jet and a Holley 600cfm, and I put my Q-jet back on until I can get a Demon 750cfm. I have 400+ HP and have no problems with my Q-jet (as long as you keep it in tune)....so they can be modified to handle the HP you are looking for. I put the Q-jet back on when gas prices went up because the primaries on the Q-jet provide good fuel economy and normal driveability while you can mod the hell out of the secondary side. It allows you to tap into power on demand rather that use it all the time. But for overall power and gas guzzling..nothing beats a non CC carb.

------------------
Formerly known as 1984L69Z28

1984 Z28 - L69 optioned, 350HO w/ Trick Flow Heads, Drop Forged Lunati Crank, Crane Cam and 1.5 Roller Rockers, Stock Z28 Intake Manifold, Highly Tweaked Rochester Carb(700cfm), K&N Filter, ThermoMaster Chip w/ 160 Stat, Comp Headers, 3" Stainless Dual Exhaust w/ no Cat & Dynoflow Muffler, 4 wheel disc brakes, etc....

God bless us father, son, and holy ghost....whoever goes the fastest wins the most!!

 

I put a kit in my Edelbrock q-jet last night (same design as Rochester). It took me three hours from unscrewing the air cleaner to screwing it back on, and that included talking to my mom on the phone for half an hour. I've done a few over the years, but they really aren't that bad to build.

The "sticky" points are getting the rods back into the jets, keeping the accelerator pump under the airhorn gasket, and that pesky choke rod. With patience, you'll get it. A real carb cleaner you can dip the parts in and compressed air to blow out all the passages afterward are must-haves. As well as a clean work area where you can lay everything out as you disassemble and reassemble.

I assume you know you need a vacuum/mechanical advance distributor to go with your 1970 carb. I wouldn't advise using the truck's distributor unless you convert it from points to electronic.

My 396 was rated at 325 hp (gross) stock w/q-jet, and now has better intake, cam & exhaust. Trust me, top end is NOT its weak point...!

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. 0.030 over 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlock header mufflers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1/94.6 @ 5800' Bandimere.

 

this post just helped me make a decision. i think i'm gonna keep my q-jet and sell my holley 600cfm. i was given the holley when a friend replaced it on his 71 cutlass. now i'm gonna sell it and get some cash so i can upgrade my intake.

------------------
1982 Camaro SC-Z