Question: replacing carb. which is best and easy to install?

[myred73vette]

I have a 73 L82 with 750 cfm carb and want to change over to another carb I have had problems and tired of missing with this one. Which do you think is the best carb. to go with and ease of installation. I am leaning toward a Edelbrock.. Thanks for any input.

 

[Crimson Thunder]

You're going to get 800 responses to keep your Quadrajet. Mine was long gone when I bought my car. I have a Holley 670 Street Avenger on mine and i'm very happy with it.

 

[Hib Halverson]

You're going to get 800 responses to keep your Quadrajet. (snip)

You'll get 799 more after this.

But if you absolutely want something other than a Quadrajet design, I'd go with a Holley. Just understand that no 4bbl will have better response or fuel economy than a properly-calibrated Quadrajet.

 

[Vettehead Mikey]

798

 

[philbillyvette]

this guy knows a thing or two about Quadrajet carbs, read several articles in performance magazines on his product. maybe a route to go would be a well built and calibrated Quadrajet from him. i was doing research on getting one of his carbs, but then i ended up selling the car after it got sideswiped.

SMI CarburetorSMI- Sean Murphy Induction

 

[lars]

Which do you think is the best carb. to go with and ease of installation. I am leaning toward a Edelbrock.. Thanks for any input.

The dyno testing the I have done, and duplicated by dyno testing done by Cliff Ruggles, shows the Edelbrock carbs (re-pops of the old Carter AFB) to be the worst choice for performance. If you need a cheap carb just to get a car running, with little setup hassle, get the Edelbrock. If you want the car to run well, step up to something else.

If you want good performance combined with best fuel economy, stick with a well-tuned Q-Jet. The Q-Jet will produce significantly more torque in the low- and mid-range than any square-bore carb. The last back-to-back dyno run I did on a Q-Jet versus 750 Holley had the Q-Jet kicking out 100 ft/lbs more torque at 2500-3500 rpm than the Holley on a 428 Pontiac engine.

On the top end, the sqaure-bore design of the Holley gives it a slight edge, but it depends on which "Holley" you're talking about: The cheap Holleys are cheap. You get what you pay for. The carb to consider would be, at a minimum, the "Street HP" to get a good level of performance. If you currently have a Q-Jet and stock manifold on the car, keep in mind that converting to a square bore carb also involves swapping over to a square-bore manifold, fabricating new fuel lines, obtaining throttle cable brackets that will work, and figuring out your vacuum hose routing on a carb that has half the vacuum provisions of a Q-Jet.

If you're considering a square-bore carb, such as the Holley HP, you could also consider the QuickFuel carbs and the ProForm - these are also very good products. BG ("Demon") just went out of business, so that option is no longer available except as remnant stock at Jeg's - I've had very good luck with the BG products.

There is no "ease of installation" when swapping over to a completely different carb. If you are replacing the Q-Jet with somthing else, there is no direct replacement, and on-engine tuning will be required to obtain the best level of performance once you get all the fabrication taken care of. You can e-mail me for my "BG Carb Installation Paper" to get an idea of the installation issues involved in swapping to a square-bore carb.

Lars

 

[White75]

The dyno testing the I have done, and duplicated by dyno testing done by Cliff Ruggles, shows the Edelbrock carbs (re-pops of the old Carter AFB) to be the worst choice for performance. If you need a cheap carb just to get a car running, with little setup hassle, get the Edelbrock. If you want the car to run well, step up to something else.

If you want good performance combined with best fuel economy, stick with a well-tuned Q-Jet. The Q-Jet will produce significantly more torque in the low- and mid-range than any square-bore carb. The last back-to-back dyno run I did on a Q-Jet versus 750 Holley had the Q-Jet kicking out 100 ft/lbs more torque at 2500-3500 rpm than the Holley on a 428 Pontiac engine.

On the top end, the sqaure-bore design of the Holley gives it a slight edge, but it depends on which "Holley" you're talking about: The cheap Holleys are cheap. You get what you pay for. The carb to consider would be, at a minimum, the "Street HP" to get a good level of performance. If you currently have a Q-Jet and stock manifold on the car, keep in mind that converting to a square bore carb also involves swapping over to a square-bore manifold, fabricating new fuel lines, obtaining throttle cable brackets that will work, and figuring out your vacuum hose routing on a carb that has half the vacuum provisions of a Q-Jet.

If you're considering a square-bore carb, such as the Holley HP, you could also consider the QuickFuel carbs and the ProForm - these are also very good products. BG ("Demon") just went out of business, so that option is no longer available except as remnant stock at Jeg's - I've had very good luck with the BG products.

There is no "ease of installation" when swapping over to a completely different carb. If you are replacing the Q-Jet with somthing else, there is no direct replacement, and on-engine tuning will be required to obtain the best level of performance once you get all the fabrication taken care of. You can e-mail me for my "BG Carb Installation Paper" to get an idea of the installation issues involved in swapping to a square-bore carb.

Lars

What's the count to now? 795?
Listen to this man, he knows what he's talking about.

 

[Copdogcorvettes]

I have a 73 L82 with 750 cfm carb and want to change over to another carb I have had problems and tired of missing with this one. Which do you think is the best carb. to go with and ease of installation. I am leaning toward a Edelbrock.. Thanks for any input.

Well this will be #1 for the other side. I went thru about 3 Q-Jet and still couldn't get mine to run the way I wanted. Finnally I put on a 650 Spread-bore Holley; It's be on there for 2 years now and Love it. I've got tire smoking performance, and 17+MPG on the Hiway.

Holley is easy to tune and adjust; None of that needle, seat, jet and the rest of that stuff. The Holley is just better and easier to work on; but that's just my believe. (After 30 years of running Holley)

Gary

 

[SVO]

My opinion is to stay with your present Q-jet and have it rebuilt by a Q-jet specialist. I'd recommend not picking up a rebuilt unit from your local AutoZoo or similar parts house. Parts house rebuilds can be problematic. Second option would be to go with a Holley spreadbore, as it will fit your stock L-82 manifold. The spreadbore is only available in a 650 cfm model, and you may lose some performance by stepping down from the 750 cfm carb. Third option would be to go with a Holley square bore but that would require a manifold change. If you change manifolds, beware that most aftermarket high rise manifolds will have hood clearance problems when used on Corvettes. If you go with something like a Holley 3310 750 cfm carb, you can use the vacuum hose routing for a '72 LT-1 to figure out hose routing for your car.

 

[lars]

The spreadbore Holley is a viable alternative if you cannot find a suitable Q-Jet. The Holley spreadbores do bolt up to the stock manifold, but throttle lever configurations and vacuum hose connections will be different from the stock carb on the engine, making some fabrication work required.

The new spreadbores are available in 650 cfm, but there are a lot of used spreadbores, in good condition, that can be picked up for a fair price. There are 4165 and 4175 models, and many of the 4165's are 800 cfm. List numbers such as the 0-6211, 6212, 6213, 6262, and many more, are 800 cfm 4165 spreadbores. Properly set up, these can be made to run just fine.

Lars

 

[terry82]

i think the key to it is ,to have the what ever carb you get. to have the right pro set it up .its hard to take a carb out of the box to fit your needs run right.

 

[Hib Halverson]

I've used all three–Quadrajet, Edelbrock AFB clone and Holley–on my 71.

Unfortunately, as much as I like many other Edelbrock Products, my experience with the Performer four-barrel (the Carter AFB clone) was not so good. I found the carb impossible to tune for good drivability and the AFB's poor fuel control (ie: the fuel "slosh" that had GM switching from AFB to Holley and Quadrajets after 1963) under braking was a big problem...to the point that under heavy breaking, the engine would run so rich, it would stall.

My experience with the Quadrajet was outstanding...until my modification program went beyond 450-hp. I found the Quadrajet fairly simple to tune for drivability and farily simple to modify for increased performance up to a certain point...say 450 hp. If my engine was still down around that level, I'd still have a QJ on it.

I think, for a street high-performance and/or street track engine of 450hp or less, Quadrajet is the best choice because of it's ability to make good power yet also have great drivability and good fuel economy. For up to 350 hp, you need a 750. More than 350-hp, look for an 800 cfm Quadrajet.

For race-only engines or very aggressive steet high performance engines making more than 450 horses, the traditional Holley 4150 is the way to go. Currently, I use a highly-modified 850.

The highly-modified part is what I've had to do to get the Holley to have good drvieability and fuel economy as well as make lots of power. The Holley, while easy to tune for wide-open throttle performance is more difficult to tune for light throttle drivability and fuel economy.