Greetings Vetters......I want to replace the stock quadrajunk on my 79....and I was toying around with installing a Eldelbrock 650 AVS 2.....any thoughts or feedback.

 

I had a new edelbrock 600 on my 74 when I bought it and had nothing but problems. bad flatspot and its an inferior, older design than the quadrajet which is a 750/780cfm capable carb with better performance. my quadrajet was damaged and I know nothing of rebuilding or tuning them so I bought a used holley street avenger 670 and had no issues rejetting and replacing the power valve to suit my car but many say they are lousy carbs too.

 

I also run the 670 . Once tuned ,my mild 350 runs great.I have had people at car shows think it has fuel injection.because it starts up so fast hot or cold.

 

Must say, I've read on here that the Holley 670 street avenger is a **** carb. But I bought one somewhere around 2003. I remember playing with it a bit dialing it in in the beginning. After some jetting, playing around abit with springs for secondary opening. It started and ran fine. I sold it on a little over a year ago. (Changed over to EFI). The Holley is easy to work on. Get parts for and it seems plenty of people know how to get them dialed in if you don't. The Quadrapuke on the other hand. Seems finding someone who truly knows how to dial one in. .... well.
so I to would suggest the Holley.

 

I wonder how Edelbrock was able to start selling carbs at the Auto Parts store.......they sure infiltrated the market. Others have used them with mixed success but myself and many other informed sources will tell you that you have to ask yourself why you are replacing it. Every novice Vette/Musclecar owner in their life it seems thinks about putting a different carb on their car will yield some kind of benefit.
But here are the facts:
1) A carburetor by design only does three things....meter and distribute and mix fuel.
2) There are many different ways to go about this...but they all end up achieving the same goal.
3) 95% of carb problems are ignition and ignition timing....but since most do not or do not want to understand timing, it is easier to bolt this new thing on top of an engine and say you did something.
4) The 68-81 Corvette 327/350 had a Quadrajet on it, unless it was an LT-1. The Quadrajet is one of the most misunderstood units in all of autodom and was bashed by uninformed mechanics in the 70's/80's as inferior, when it was actually one of the best fuel mixers ever designed and powered millions of GM products.
5) Up to the 400 horsepower level.....there is zero benefit with replacing a Q-Jet with anything else, in fact....most swaps will make it run worse and be down on power.
6) Here is the big one- An Edelbrock is square bore carb. Most every C3 has a spread bore intake. There is an adapter for this that is one of THE most terrible pieces of **** ever designed. The mismatch it creates in the primaries causes all different kinds of running issues that the average guy does not understand. Period. I work on many old cars, and I WILL NOT work on yours if you bring it to me with this setup. I have one in the driveway now...a 72' 350/200 4 speed all original except a shop here lost his original carb and the "neighborhood mechanic" put an Edelbrock 600 with adapter on it. It runs fat....pops out of the hole and although it is a month old and has approximately 200 miles on it...there is black reversion down the carb throat that always happens with this setup. I have a nice Q-Jet on the shelf...so it is going on the customers car.
7) Not to say the AVS 2 is a bad unit....if you change the intake out to a 2101 Performer or 2701 EPS, it will work great....but only if you are prepared to jet/calibrate it. I am leaning away from all Edelbrocks now as they only want 5-6 psi of fuel and any more causes flooding conditions and a myriad of other problems......with so many great options now, for that reason alone, I will not spec an Edelbrock carb anymore.
8) If your Q-Jet is working fine....leave it. Spend the money on some ceramic coated long tube headers and a real exhaust system....this is something you will notice.
9) Any square bore carb you try to adapt to the stock intake is going to give you problems.
10) Setting proper jetting on an Edelbrock is just as difficult if not harder than a Q-Jet.
11) After over 20 years.....Edelbrock still doesn't have a real lehmens manual for the average guy to understand and will give you the run around when you call them. They don't care about you or your car.....they care about selling carbs with the largest marketing budget in the business.
12) When you bought a real high performance Vette engine option in the 60's and 70's.....GM scrapped the Carter AFB (nee Edelbrock) for a Holley 4150/4160.....think about that.
13) All carbs will seem lousy if your setup, and follow through is lousy.
14) 300,000 or so Corvette's came off the line new with a Q-Jet, if you bring a Q-Jet back to the way it was when new, it will run exactly the same as new...all things considered.
15) 90% of all remanufacutred Q-Jets are pure garbage...10% are good. Do you want to play the odds of what to pick?

To the OP.....greetings, I am from Clarkston....born in Pontiac. Have they tossed Witmer out yet? LOL.

Thank you for listening to my morning rant. LOL.

Jebby

 

If it's the original carb, I'd like to buy the high performance Q-Jet off your '79. E-mail me with price and carb number.
Lars
V8FastCars@msn.com

 

 

Duplicate post.....

 

Maybe he's got two "Quadrajunks"

 

Lars nailed it!

To be clear, you're talking about replacing a carb that came out in the mid 60's and was refined through the 70's - you honestly have one of the best QJet designs there is, and replacing it with a carb that was came out in the 50's and deprecated in the early 70's.

I could understand going to a Holley 4-barrel - they're easier to work on, easier to do quick changes at the track and super modular, but you won't see a perf difference from a well-tuned Q-Jet.

 

yep

 

Update...... I rebuilt my qjet.... And the car ran perfect.... Untill the Module smoked

 

Update...... I rebuilt my qjet and added a fuel pressure gauge and a fuel pressure regulator and set it to 4.5 psi... And the car ran perfect.... Untill the Module smoked

 

See? Your carb ran so well the ignition couldn’t handle it.

Thanks for following up!

 

Hay Shark....
That's awsome!!!! Lmao!!!!
Also.... Just to let people know....
The Qjets aren't so bad!!!!

 

...So does that mean you're not going to sell it to me cheap...?
Damn....
Lars

 

I replaced my Carter and ALL Hollys with Qjets for 2 reasons.

#1 gas milage
#2 performance, hands down!
#3 Lars knows a good carb.
#4 best thing I ever done.
Now my 67 has 3 holly carbs, but I will deal with that. After many gas milage checks the Qjet made all others look bad and gave more performance.
Easy to work on and just have to adjust the secondary spring correctly.

Dom

 

Lars.... Nooo!!! Not. now!!!

 

Keep your #'s and send it out for one of the experts here to restore. You will be happy.

Dom

 

Bad way to ask for advice...QuadraJUNK really?????

1. You don't understand carbs.
2. You are maligning the best carb ever made by man.
3. They probably made something like 300,000,000 of these....do you really think that GM would refine the carb over 40 years and keep making junk? Can you IMAGINE the warrantee hits in $$$$????

My advice....send your carb to Jebby/ Lars, have them/him rebuild it for you.

I have had a 4MV for 45 years...SAME carb. Junk HARDLY!