Hi guys,

I'm considering going to an aftermarket carb after issues with the quadrajet. I want to buy a carb that will fit under the hood with the stock breather equipment. I have a 79 L82 with a holley spreadbore aluminum intake.

I've read a bunch of comments on here, and honestly just got more confused, but I really need some guidance on what actually fits under the hood.

Thanks,
Gary

 

I'm currently installing a Quick Fuel 650 Double Pump with Annular Boosters. I have a solid lifter 350 "LT-1 Clone" engine with double-hump heads and a dual-plane aluminum GM intake.

Whatever you get, I would definitely spring for the Annular Boosters. My understanding is the part throttle fuel atomization is FAR superior to regular dog-leg boosters. There is slightly less room in the barrel throat, so there is a very small amount of peak flow lost, but at the benefit of low-end torque.

The 'comparison' review I read had a side-by-side bench test on a ~400 hp engine of an annular vs. dogleg style carb and the annular carb was generating nearly 100 ft-lb MORE at 1,500 RPM than the dogleg. There was no point in the power curve where the dogleg outperformed, though the differential diminished to a few HP at the top of the test. They would have crossed if the test was carried out to 7,000 RPM.

But really...how much time do you spend above 5,500 or 6,000 RPM? Versus 1,500 to 2,500?

I did have a problem with my stock throttle bracket and cable with the extra spring weight of the double pump, though, so plan on upgrading that as well. I'm installing a new Lokar setup when it comes on Wednesday.

I have yet to run the car on my new setup...I'm keeping it "dry" until I do the throttle cable so I can set the cable pull through both the secondaries without flooding the crap out of my engine.

The Quick Fuel is definitely a nice piece. Putting my money where my mouth is, I'll tell you that if you put a Holley and a Quick Fuel on a bench, there really is no comparison.

For a Holley 110 GPM fuel pump, new push-on fittings and lines, braided distrubution hose, new Lokar cable, springs, and bracket, new NGK plugs, and the Quick Fuel carb, I'm coming in a few pennies short of $1k.

All that because I got a piece of varnish stuck in my needle valve while in a 12 car convoy up to a Corvette show and had to get towed 35 miles. Just fixing the problem once and for all!

 

Get lars to go through your Qjet imo best overall street carb.
Love em but dont know jack abot tuning them.

Running an AED850 but irrelevant to this thread not really a street motor.

 

What are the issues w/the QJet?

 

Of course I offered an opinion without actually answering your question:

I don't see why any Holley 3150 or 4150-framed carb should NOT fit under your hood.

As my post pointed out, there may be a few other issues if you go with a mechanical secondary, but you'll have those same issues going from a Q-Jet to a Holley frame since the way the throttle cable mounts is different...I belive that is the case, anyway. The Q-Jet bracket is different from the Holley bracket.

 

the fuel inlet where the filter goes is stripped. we removed the fitting, not knowing that it had already been stripped and repaired. now, the adapter used to fix this problem cannot be used again. so, it looks like I need a new carb. don't need which way to go.

 

I can fix your stripped Q-Jet.

Lars
V8FastCars@msn.com

 

Lars + Q-jet = from what I've heard (and I believe it)

But for out of the box SIMPLE...no fuss, no muss Edelbrock 1406

 

Honest question for the brain trust: If 'correctness' is not an issue, why would you replace a Rochester Q-Jet with a new or rebuilt Rochester Q-Jet?

If you're spending the money anyway, a newer, more advanced carb is a wonderfully simple and effective way to "let more than a few ponies out of the stable", as it were.

 

Best advice I could give.
I'm still running my Q-Jet on my mildly modified 81 motor. It works great and I still get 17-18 mpg is mixed driving.

 

@Keith - If you want a newer, more advanced carb, I suggest you consider a modern fuel injection unit. Other carbs may offer more CFM than a Q-Jet, but none are better at driveability and fuel metering over the entire range of driving needs. Others will chime in; that's just my 2 cents...

 

Getting a FI kit that feeds anything over 400 HP is $2,000+. And it is a fairly major bit of work to install, with the electric fuel pump and all.

I had a hard enough time justifying $1,000 through the CFO.

A well tuned carb will come very close to the 'feel' of a FI system, anyway. If only a small bit more tempermental. And, of course, less efficient. I figure I'm in the 10 to 12 MPG range.

The annular booster is supposed to be the fo-shizzle, though. I have high hopes.

In all honesty, I'm a little surprised to hear such high praise for a Quadrajet. Don't see many aftermarket companies tripping over each other to come up with their newer and better version of a Rochester. Much less have all the track guys drooling over my awesome Q-Jet. I'm not bashing...I have absolutely no dog in the hunt. I guess I'm the one that is missing out.

 

the basic problem is that they are for the most part 40+ years old and as a result may not work as good as new....also the possibility of inferior rebuilding at one time or another......a good specialist could cure that issue.....{Lars maybe}

they are very good carbs but!

 

Plenty of guys getting 20+ MPG with carburetors, even without O/D. O/D will put you there easily with a well tuned carb.

The issue between EFI and carbs is in adaptability... an EFI system can instantly react to changes that a carburetor otherwise could not. Such as significant temperature or altitude changes...

 

same carb im running. had to get adapter to make it fit my factory intake.you may have a hood clearance problem though. im not sure my car came with the big hood scoop already on it.
billy

 

I found a local carb shop S&S here in Houston to rebuild the quadrajet. He seems really knowledgeable and professional. Also wanted to know which cam I was running so that he can set it for my engine. I'll let yall know how it turns out.

Thanks for all the help. I appreciate it.

Gary

 

Nothing wrong with a Q Jet IMO. I rebuilt mine that was in my oem '69 350/300 when I put it in my ZZ4. Changed jets, the needles, the hanger & put in a "small float. Runs strong without any issues. I never even considered a Holly replacement - FWIW.

 

garym52 If you don't get good results from S&S, try Zepeda in Pearland. He rebuilt the original qjet on my 1970 big block. OMG! Absolutely awesome performance for put your spine against the seat torque and it makes that famous qjet sound when those big secondaries open up. I don't know S&S and hope they do you a fantastic job, just wanted to mention someone I've used.

 

Thanks for the info....I wasn't aware of Zepeda but my office is in Pearland so that would have been great. I'll look him up if I have any issues. Are you from this side of town?

 

Just make sure they don't put one of the self-tapping oversized inlets in it or one of the O-Ring inlet fittings - these can destroy the float bowl casting. They need to have the tools and capability to correctly machine the inlet and tap it for a stainless helical thread insert in order to do the repair correctly - this insert is a non-standard thread size, and is not available in your local hardware store.

Lars
V8FastCars@msn.com