What carb should i run

[YellowBeast1969]

Hey guys, i'm a newbie here as most of you probably know. I'm still learning this american V-8 thing, as i used to race only imports. But anyways, i just got my 69 Vette a few weeks ago, and I'm working on bringing it back to its original performance and then some. Right now, the Carb on it is a Holley 650 CFM with electric choke. And a couple days ago, my dad gave me a new intake manifold that he had in his attic. The new one is an Edelbrock double carb and he says i can run 2 480 CFM Holleys on it. I'm wondering if it will be worth it to buy 2 new carbs, or should i just stick to the 650?

Thanks for your input. -Jim

 

[resto75]

If it were me I would stick to the one carb you have. Your asking for problems with two carbs. Kind of double trouble.
You have the right carb now so why take a chance.

 

[cruisin-davey-g]

Hi Jim: What size motor do you have?

Dave

 

[YellowBeast1969]

Its got a 350

 

[SwaveDave]

I think youll find that 2 carbs for your 350 engine is going to be too much carbueration and youll never get it to run right. Plus, youll be constantly adjusting them to work together.

 

[woobie1966]

two carbs would be hard to adjust, if you are not familiar with carburation (dealing only with imports, i assume were fuel injected) get some professional help in tuning the carbs. if i were you i would go even smaller (holley makes a 390 cfm 4 bbl),
if you can get it to work, it would: 1 perform well, and 2 look cool
if you want ease stay with what you have.
mike

 

[MoeJr]

Stick with the one Holley. Much easier to maintain and for a newbie to american carbed v8's it is a good starting point. Maybe down the road after you have had the car a while and learned the ins and outs of the beast then try the 2 4bbl setup with 2 390 cfm Holleys. Just my .02.

Moe

 

[GerryLP]

Jim,

The two-carb set-up would be a plus when it comes to volumetric efficiency, for with the two Holley 390 CFM carbs it would have one jet for each cylinder; however, today's manifolds are pretty efficient, and tend to correct situations where one cylinder would "lean" another. Tuning the linkage I am told that its difficult, but even then this would be workable.

Definetely, learn and tweak the single four barrel carb first before attempting multiple ones. Unless you have other transportation that you can use while you mess around with the Vette, the use of the single four barrel is best at this point.

One good carburator source book is the Holley Carburators, Manifolds & Fuel Injection by Mike Urich & Bill Fisher. The Berkley Publishing Group manages it, and it's probably is in its fifth edition, but I got the fourth edition about a year ago, so maybe the fourth edition is the last one.

As always -not all books are strong in all subjects, so this would be a good start, but don't stop there.

 

[WhalePirot]

used to race only imports

Welcome to the REAL world...

No question. Stick with the single 650. Learn how to adjust and tweak it to run properly, without the issues of dual carbs---balancing/synching/etc.

I ran a Holley 750 dbl. pumper on a crate LS-6 (454); turned 6500 rpm with no air starvation. You'll gain no high rpm breathing and could quite well caused problems with the dual setup at the low end.

I don't buy the volumetric efficiency thing at all. :argue More would be gained through head/intake work than with a simple dual carb approach.
Mike

 

[JohnZ]

Don't bother with the dual-quad setup - they're more trouble than they're worth (Chevy gave up on them in 1961); the Holley you have now willl work just fine. All the real big-power engines from then on had single 4-barrels (except the Tri-Power L-71's, which were marketing-driven, not engineering-driven, and only lasted three years).

 

[cruisin-davey-g]

Its got a 350

Hey, "Yellow Beast": You're 69 sounds like a nice one. The only reason that I would put the Dual Quad set up on a car like the one you mentioned, is if I were "showing" the car to impress everyone that looks at it. As a regular driver, it's really too impractical. Unless you're motor is "beefed" up enough to handle it, you'll be asking for nothing but trouble with the dual quads. Besides, the 2 480 CFM's you mentioned before would be WAY too much for the motor. If you are still deciding to put the set-up on the motor, go with at least 350 CFM carbs for the small block. That will be plently for a "street-strip" motor. Still, if your motor is mostly "stock": I'd forget the whole thing altogether. Good luck on what you decide to do.

Dave:

 

[GerryLP]

I don't buy the volumetric efficiency thing at all. :argue More would be gained through head/intake work than with a simple dual carb approach.

Like I said, todays manifolds do a pretty good job; however, the volumetric efficiency benefit is a fact...

(except the Tri-Power L-71's, which were marketing-driven, not engineering-driven, and only lasted three years).

I believe that is true; however, recall that those tri-power or cobra-jets really used vaccume secondaries which really self-adjust to the signal received from the primary side of the carbs (some even were installed with the vaccume sides towards the front of the engine...I believe.)

Regardless, I am still not ready to mess around with dual-quads (lazy I guess)...:L

 

[robert kirk]

I run 2x4's on a BB. This is a low profile intake not a tunnelram. The response is on par with a ir system. This is not a stock motor. It has a roller cam with 560, 566 lift, 280 duration. 110 center. alum heads, 10.3 comp. I have no trouble with fuel puddling, but 2x4's can be set up to run insinc, or progressive, what ever you would like with very little problem. the carbs are 550 edelbrock's. I used these because they are easy to tune, and have no gaskets below the fuel level. There are several companies that make linkage, and fuel systems if you don't want to fabracate your own. I found the setup and tuning of the 2x4 set up to be no harder than a single four setup. I also think a single 4 will make more torque, do to the advances that have been made in intake design, But when you pop the hood the cool factor of 2x4's is hard to beat. If you want i can post some dyno runs showing the fuel flow #'s from about 3thou upto 5800. If your wanting tar top ori, or are looking for every # of torque then a single 4 is the way to go, if cool, neat-o, or other emotions are involved then 2x4's is a good choice. With a little brain power and labor you can have a trick setup that works great and looks really neat. robert