Question: Stock Q-Jet or Edelbrock

[Thore826]

Ok, I have a question which was probably answered many times before, but I'm new to posting here so bear with me! We restored my '75 L-48, interior and exterior; we got lucky with the mechanical, not much to do. The car sat for about 12 years, and just needed a fuel pump to get it started. Then the other parts died off over a three-month period (radiator, power steering pump and hoses, etc.) Finally, overheating messed up the carburetor. We were going to just go up to Auto Zone and either rebuild the stock carburetor or get a rebuilt one, but I was also considering getting the Edelbrock Performance Carburetor and Intake Manifold from Summit. is it worth it, or would a tuned Q-Jet work just as well (fuel economym, power)? The Edelbrock is claiming that it'll perform better than the Q-Jet, but I know not to trust everything the internet tells me! I only want to do this once, so anyone have an opinion; Edelbrock or Q-Jet? Thanks (sorry for the long post)

 

[baxsom]

i would say send the carb out to be rebuilt by a pro or replace it with a reman from jegs
http://www.jegs.com/p/JEGS/752437/10002/-1/10271

 

[LVMYVT76]

There is nothing wrong with a correctly tuned stock carb, it came from the factory that way and was engineered to work properly. Now, to find someone that rebuilds them correctly is a bit of a problem, even buying a rebuilt from a parts store doen't mean it was done right. I sent mine off to a person who not only rebuilds them, but restores them, costs a bit more, but worth it.

 

[Vette79]

Stick with the Q-Jet. Power,Economy and they are easy. Aslo, do a search on this topic in this forum. I'm sure you will find some helpful information on the Q-Jet.

 

[Vettehead Mikey]

Finally, overheating messed up the carburetor.

Engine overheating does not cause a carb to permanently malfunction. What makes you believe that it needs rebuilding?

 

[Thore826]

I think I worded it wrong, tune up is probably right. Nothing has been touched mechanically on the car since it came out of the showroom, I think the spark plugs I replaced were stock. But whenever I really put the pedal down, the engine bogs out, and it'll stall out if you dont let off. I was talking to a few people and they said it sounds like something with the carburetor.

 

[Hib Halverson]

A useful answer to this question is going to depend partially on the condition of the existing Quadrajet. If you have it apart, what's it look like inside?

 

[Thore826]

No, we didnt take it apart so I'm not sure what it looks like inside. It's the original carb, and the car was not maintained very well over the years. Why, if I did take it apart what should I be looking for? Thanks

 

[Thore826]

BTW, I appreciate all the help, but don't go out of your way. I plan on keeping the stock carburetor; its just a question of which would perform better if tuned properly, a stock Quadrajet or the Edelbrock w/ the Edelbrock intake. I just figured since the '75 is probably the weakest year if it was possible I'd try to get some performance upgrades w/ the repairs. I already swapped out the old exhaust for sidepipes, and if it does come down to replacing the carburetor I was reading that the Quadrajet can perform very well if used properly, but no one said anything in the other posts about how well the Edelbrock performs with the new intake manifold.

 

[Vettehead Mikey]

Swapping brands of carb will make little or no difference in power output on your engine. Swapping manifolds will give limited benefits and may create some side effects (reduced bottom end tq.) that are undesirable. Not worth it IMHO, the OEM manifolds (intake and exhaust) are already pretty good.

To get serious power out of a '75 L48 (I guess you're aware that this was a 'landmark' engine in the history of the Corvette) you might want to bite the bullet and think of a crate engine.

 

[Thore826]

Thanks. At the moment I'm not ready to swap engines, but I knew that would be the best way.

 

[Voodoo81]

follow-up question

I have some follow-up to this question.

I don't think my '81 quadrajet has ever had any TLC (starting is a bear that has amounted to copious amounts of carb&choke cleaner sprays into the carb). Am I able to buy one of the rebuilt ones from Jeg's as was posted, or will there be some issue due to the computer controlled issues that us '81-and-later owners face?

I realize that the carb may not be the solution to my problems, but it's in the works anyway as I restore this vehicle and prepare to either conver to stroker 383 or drop in a ZZ4 to cure my oil burning/dripping/lack of power problems.

Thanks for any advice/help.

John

 

[Rodney Gold]

If you gonna uprate the engine , you might as well get a decent carb right now....
A Holley 770 street avenger or the like would be desireable for a mil;d to wildish performance engine , or a simple 600 cfm Vac sec for a mild street motor.
I would go the 770 route , even tho its big for the engine right now , it's easily tuneable for just about any conditions unlike the Edelbrock's which are not that easy to tune to the nth degree.

 

[Vette79]

John, if you are going to stick with the QJet, and I see no reason why you shouldn't, here is someone that has worked for a few of us in the past that will help you with your QJet. I'm currently running a QJet he built for my application. Only adjustments that I needed to make were with the idle mixture screws. Here's his link: http://search.ebay.com/_W0QQsassZmountaintink

Here is a link to my build that has the QJet installed:
http://www.corvetteactioncenter.com/forums/showthread.php?t=103334

 

[Copdogcorvettes]

The old Q-jet is a very good carb for both performance & mileage when they are tuned properly. If you are going to rebuild it then get someone who know what they are doing with Q-jets.

I'm an old school Holly guy; so I have a Holly spreadbore 650 on my '78. The spreadbore was made for the SB 350, small mains and dish-pan secondaries. There is nothing else that works so well, short of TPI, for a Corvettes.

I know someone will disagree and that's fine, but GM came up with the spreadbore and it works.

Gary