h82stop

Good Afternoon boys and girls.
I just installed a 383 in 73 Corvette. I have a chance to get a great deal on a 750 Holley dual pumper 4779-C from a buddy who bought it for his stock 350 but it's too big.
Here are the specs for my motor. 9.9:1 compression, 2.02 aluminum heads, hydraulic cam with a 240-246 @.50 duration and 537-540 lift and a 4 speed. Would my motor be able to handle this carb or would I be better off with a 650. As usual thank you very much for your help. You guys make car life a lot easier.
Charles

Gordonm

The 750 should work fine if it is properly tuned. I ran a 750 DP on my 350 for years tuned correctly though.

SH-60B

750 is not too big for your combination, or even your buddies stock smallblock. Most 70s Corvettes had 750 carbs on them. A 650 would leave some power corked up on your combination. If your buddy did some changes to it, return it to "as delivered" specs (jets), it will be quite close to what you need.

mikem350

You have a great engine combo that could use the air of a 750! Many members here use this carb.

I just went thru my 750 DP, has #72 pri and 80 sec jets (as delivered)good starting point!

Les

Add me to the list of those giving you a . That's actually a great match for your engine. Your 383 will be very happy with it. We can help with tuning if it needs it. Just make sure your accelerator pumps are properly adjusted and then see how it runs.

BEVO76

750CFM all day long on that combo. I prefer the Holley Classic 750 but thats just my preference.

pauldana

Thats a big cam... why did you not go 11:1 if you had aluminum heads? Would have been better with that cam..

A 750 DP is not to big,,,I ran a Demon 750 (Demons were known to flow more than advertised as well) and that engine ran so amazing, that when I snapped the crank, my son took it and rebuilt it with a new forged crank...and he says it going in his C2 that he is going to get some day... 750 is fine..

BOOT77

Let me put it this way a 750 will work and may or may not require more tuning, so idk what your tune ability is. A 650 is a safer bet for needing less tune with better drivability. If it's your friend can't you just try the carb out?

Little Mouse

the 750 is the right size. but that cam is to big.

BlowAMouse

No mention of intake manifold or rear end gears. If your manifold is limited to 5500 RPM then some tuning to the 750 will be required. If you’re spinning above 6k, the 750 will feed the top end nicely. As already posted, it will be up to your (or your buddy’s) tuning ability.

Smash the loud pedal and see what happens….

BlowAMouse

and to answer your original question, My wife tells me that SIZE DOES MATTER.....

SH-60B

You mean like, blowamouse? Lofl!

keithinspace

My engine: A 10.5:1 compression straight no-bore 350, 200 cc aluminum head, SOLID roller cam with 248/254 duration @ 0.050 and 0.576/0.582 lift with a 4-speed.

Personally, I run an Quick Fuel annular-booster double-pump 650, and here are my reasons why:

--I knew my engine build would leave "a little to be desired" in the low-end-torque category.
--I knew I would always run a dual-plane intake to amplify my low end torque.
--I knew that I would never run over 6,000 RPM even though my engine is safe to run to 7,000 RPM. Just a longevity/durability thing. 6,000 RPM is PLENTY.
--I knew that the choice of a 650 would incrementally amplify my low end torque at the sacrifice of high-end volumetric performance (which I'm not using)
--I knew that the choice of an annular booster carb would amplify my low end torque (better atomization) at the sacrifice of high-end volumetric performance (which I'm not using) (the annular boosters physically take up more of the sectional area of the carb throat itself, so not as much air can pass through in the over-6,500 RPM range that I'm not using anyway)

So...that's where I ended up. I built an extremely knarly, knobby, cam-heavy engine to scare small women and children and fitted it with a bunch of things (including a 6AL MSD system) to increase its driveability and low end torque so I'd be comfortable farting around town.

The engine is a MONSTER and has turned out to be an amazing combination. It has a NASTY idle and produces well over 450 hp at the flywheel (based on the known horsepower of the cars I've beaten). My 0-60 right at 4.0 seconds if I get a really good launch. Which is tough, by the way.

I do have some "cam surge"...mild part-throttle bucking below 2,000 RPM...but that's just part of the deal. I ADORE the character of the car and wouldn't change a single thing about it.

I would pick up a fair amount of power if I added a single-plane manifold and a dogleg booster 750, but it would ALL be over 5,000 RPM and it would HURT my sub-4,000 RPM performance. Great for a drag strip. Sucky for around town driving.

ALL THAT SAID, your 383 will pump more air through the increased displacement, although with a slightly less aggressive cam. If you are at a 5,500 to 6,000 redline, I'd be on the fence...either would work fine. Your choice. I'd PROBABLY go with the 650 double-pump personally, but that's me. If you're above 6,000 RPM, I'd probably give the nod to a 750, especially if you go the annular booster route.

That was my thought process. Hope it helps.

427Hotrod

You'll be fine. A 750 DP is about the most universal carb out there...will run well on just about anything.

I've used the same one on a stock '82 Mustang GT, a stock 350 Vette, a hot rodded 350 Vette, a stock 327 Vette, a hot rodded 327 Vette, a nasty 427 Camaro, more nasty 427 '57 Chevy, Roadrunner with a near stock 440and a mildly built 383, a mildly built 454, and a seriously nasty 350 in a Camaro pure race car...and who knows what else that poor thing has been on? It just flat works with minimal effort.

The biggest issue with most carbs is people mess with them too much. The "universal" DP's come from the factory aimed at an engine with a larger cam (less vacuum) and carb signal. They have no idea what you're going to bolt it to, so they had to make an assumption. If it's a very mild engine with super strong vacuum signal it "may" pull too much fuel at lower speeds and seem rich. That's simple tuning. Carbs are designed to handle a wide range of airflow..they move fuel based on what air is moving though it. No need to go crazy on them.


JIM

BlowAMouse

ya, use to be SqueezeARat.....now i'm old...

fishslayer143

It will work fine on your engine , especially since you have a manual trans, and if you have a dual plane intake .. I personally Prefer QuickFuel to Holley, but that carb will be fine .. You probably will need to change Powervalve to match your cam s vacuum characteristics, or it will open way too soon causing flooding ..

keithinspace

EXCEPTIONAL point and sometimes overlooked. I had the absolute WRONG powervalve in my carb and it wrecked my tuning. Caused me to advance my curve way too early to cover all the fuel my powervalve was dumping into the engine. It was a difficult learning curve for me, no pun intended.

My engine pulls about 7 inches at idle.

Ultimately, I put in a 'blank' powervalve to take it out of the equation. I de-curved and de-shimmed my dizzy, and "found center" with a MUCH less aggressive combination of timing and jets.

Once I felt comfortable, I added the lowest-vacuum powervalve they make, and made incremental steps to compensate. In the end, I have a nice curve, nice jets, and not much fuel smell at any RPM or load.

And I agree with the QuickFuel feeling. Put them side-by-side and the differences are very obvious. I hate covering mine up with an air filter...that's the first thing I take off when 'showing off' my engine. Show folks the jewelry-like QuickFuel under the drop-base air cleaner.

454Luvr

In my opinion, you'll see much better mid-range torque and light-to-light street acceleration with the smaller carb. I ran a 650 Holley DP on a '72 454 for several years. It was a real killer, much more responsive than the 850 DP I tried at first.

fishslayer143

Too many people throw big cams in and never consider the effect low idle vacuum has on carb.. I have 5-In HG at idle , a 2.5 PV works well for me. Standard PV in that Holley is a 12 , it will just pour fuel in with big cams.. Quickfuel is a very easy carb to dial in with some practice,, I love them .. I have the QFSS750 DP, it runs flawlessly.