Blue_IROC_86

iTrader: (2)

When i bought my 82 Z28 it came already with a crate 350. Has Edelbrock headers. straight pipe 3" to the muffler, Victor Jr. Intake.

Now i have been reading a lot on these forums. the motor came with the 750 on it, I get the common stumble between 1200 - 1500 RPM. but sometimes under hard acceleration it breaks up. Should i downsize my carb?

built91Z28

Its a stock 350 with a Vic Jr. intake and a 750 carb? Those are both way too much. Put a nice dual plane intake on it with a 600 or 650 max and it'll probably drive much better.

I use to have a small single plane on my motor and then switched to the Vic Jr. and noticed a good amount of low end torque was gone. It definintely switched my power band up a good amount. But I'm far from a stock motor.

Blue_IROC_86

iTrader: (2)

no kidding. im still new to the carburetor scene. always been a multi-port guy. So if i switch over to dual plane with a 600 cfm will i also gain any MPG?

built91Z28

It is possible that your mileage will get better because your motor will then be built more balanced and your low end torque will improve probably letting you use less throtle to stay at the same speed.

midias

If the motor is mild yes it is to much carb. Get a 600 or 650 you will be happier.

Blue_IROC_86

iTrader: (2)

Also here's some pics.. There's no way to tell if its a stock 350 or bored 30 over. it was a crate so its anyone's guess.

built91Z28

Wether it's .030 over or not doesnt really matter. What would make it be able to use a intake/carb combo like that is if it has aftermarket heads and a decent cam in it. If the head/cam combo is stock, then its way to much intake/carb for that motor.

Blue_IROC_86

iTrader: (2)

Alright that's what I'm going to go for than. Thanks a lot..

DeltaElite121

a 750 what... What manufacturer and type of carb is it? That single plane will kill your acceleration downlow, I agree.. Get an Airgap RPM intake. The carb on the other hand is what I'm curious about.

Cosmik Debris

Yes, this is important. I'm not familiar with Edelbrock carbs but if it like the Quadrajet with air-valve secondaries then it is not too big.

Blue_IROC_86

iTrader: (2)

Its an Edelbrock 750

Savage388

Ditch the Edelbrock and go for a demon or holley 650. That's what I plan on doing anyway. Mine has the same stumble and i know the carb isnt that big for my motor so its an issue with the carb itself.

DeltaElite121

mechanical or vacuum secondaries?

1gary

Not that is has anything to do with your carb,but you could get a NHRA track that runs a super stock class to tube one cylinder to tell you if it is .030 over or more or not.

Blue_IROC_86

iTrader: (2)

Its mechanical secondaries.

Blue_IROC_86

iTrader: (2)

yes i am ditching the edlebrock. i cant stand this carb

midias

Good idea it is too big

-AO-

That 750 might be a good carb for your engine. Keep in mind the Edelbrock's use an air valve so it will only flow what it needs to. The only thing I can recommend is to put the car on a dyno. And find out what heads and cam it has.

efiguy

iTrader: (2)

Yes, Edelbrock doesn't make a mechanical secondary carb.

I'm not an Edelbrock carb fan but replace the intake first. When you use a dual plane you can get by with a larger carb. Can't do that with a single plane.
My friend has a cherry 383 69 Camaro he bought already modded. It had a big Weiand single plane on it with a Demon 750. Ran like crap. He changed the intake to a Performer RPM and kept the same carb. It was a different car after that.

Blue_IROC_86

iTrader: (2)

Alright that makes sense. I know the guy that built my motor. When he got the intake the guy he got it from said that a stock or even mild build 350 wont run with a Victor Jr.

paul_huryk

600 cfm can support up to 400hp. Keep in mind that your carb is pretty much guaranteed no to be tuned right - for either primaries or secondaries (most people live it box stock). Just rejetting and setting up the timing right might get rid of the stumble.

Blue_IROC_86

iTrader: (2)

I brought it to my buddies and we put a timing light on it.. got it set right. Then we tuned the carb and no matter what we do it still stumbles. 600cfm will be fine

midias

Are you still running the victor 2?

Blue_IROC_86

iTrader: (2)

yes i am stll running it. i have no other intakes unfortunately

cuisinartvette

Single plane and dual plane will want different jetting possibly even a different squirter.
OP if you can find a used dual plane...any of them. Performer, stealth, air strike etc and a regular ol 600 holley your car will run so much better. That Vic is way way too big for what you got.

Most carbs out of the box may need some fine tweaking.

Blue_IROC_86

iTrader: (2)

Well looks like i need to find another carb and intake... if someone wanted to trade my setup for theirs that would be nice. but my setup is worth a little more than a dual plane

midias

Look on craigslist or ebay used. That intake is designed for 3500-8500 RPM and not all that good for low end.

A RPM performer or a clone will work great.