Technical Carburetor help

I have a 37 Plymouth coupe gasser. Brand new 1968- 327. Now 331, 10.5 pistons. 1967 291 heads. Weiand stealth dual plain. Comp cam 12-601-4 cam. Turbo 400 with 3,000 stall and 57 Chevy rear end with 4.11 posi and m50-15s. Looking for a carb preference. Please let me know. Thanks.

 

Boy howdy you done it now. This will bring them all out of the woods.

In truth outside of size brand wise it is what you or the guy who tunes it for you gets along with Best. I've always gotten along with Holleys pretty good and my buddy hated them and if he got a car or truck with one on it it ended up at my place or in my truck bed. I very honestly got home from his place one day and found one in the bed of the truck where he stuck it and didn't even tell me. I'm not great on them and no expert but can muddle along with them without a battle. A lot of guys like the Edelbrock AFB clone and my experience says on a stock engine in good shape they work damned well right out of the box and they rebuild pretty well when you buy their kit.

The main thing is don't put on a bigger carb than the engine wants. I've lost track of the over carbureted Chevy 327s I have seen in my life that didn't run worth a hoot because the owner bought the biggest carb on the shelf at the speed shop.

 

^^^

There are lots of engine calculators out there on the WWW. Plug in the displacement and RPM and you will know the MAXIMUM CFM the engine will need. A slightly smaller carb will work since the air flow will not be 100% of the formula result.

 

I come up with a 575 cfm. So 600 cfm then

 

I came up with a 575 cfm. This is just a play toy. Now mechanical or vacuum secondary.

 

I have about the same drivetrain but a looser convertor and I have a 700 Holley on there with no pv and different squirters and jets and it does good. But It stays 2500 and above all the time

 

Mr48Chev said it VERY well!

When Carter Carburetor Company was still in business, Carter recommended a 625 CFM (4759s) for race use, and a different 625 CFM (3721s) for performance street use.

Your question about mechanical or vacuum secondaries is a Holley question. Carters are a "demand" secondary, so they do not fit either of your categories. The 4759s is more aggressive than the 3721s in opening the secondary.

Jon

 

If you do run a mechanical secondary Holley it should work well with 3000-stall converter and 4.11 gears, I'm guessing your cam will also like a lower number power valve, about a 4.5 or 3.5 to keep it from running rich at low manifold vacuum during the choppy idle.

 

don't forget about quadrajet carburetors. we ran holley for years and tried a quadrajet and the truck is clearly faster and gets better fuel mileage.

 

For driveability I'd go with vacuum secondaries. They open the secondaries based on demand. If you are racing then mechanical is probably what you want.

 

What’s interesting is the carburetors used in the 60’ muscle car era. By the “calculations” they were over carbureted, and should have run like poop.

 

Zenith!

 

I saved the following link (video may pop up).

 

Worth a watch

 

650 or 750
Vac or Mech
Tunning required ,
With Wilson 1 inch taper spacer
Your 331 will like it

 

My 30 over 289s preference is a 750 Holley DP with a 1” open spacer, it makes 8 hp more with the 750 over the 600 and drives better. 455hp at the crank and drinks fuel like a big block.

 

Exactly the same results here. It also cured the big fuel dump hiccup when you hit the loud pedal.

 

I ran a 600 BP Holley on my 331 with 4 speed and 4.88 rear gear in a 62 nova 2

 

Yes Q J better on fuel mileage ,
With tunning on Holley you can tune a bog out
Pump cam , slots , different colors
& adjustments,
Squirters ,
Pump shots ,
P V
Then maybe deeper into air bleeds ect.

 

For those mentioning Q-Jet, I don't disagree, but the only Weiand Stealth intakes I can find are fitted for square-bore carbs, not spread-bore.

And using a spread-bore -> square-bore adapter just doesn't work well (I didn't say it won't work, just not well).

Jon

 

I’m a big fan of the Summit Carburetor that looks like an Autolite.
They’re affordable and run good out of the box.

 

Some yes, some no. The Holley carburetors used on the 350HP 327s were rated at 585 cfm.

 

My choice would be a 600-650 cfm Holley or Quick Fuel with vacuum secondaries.

 

In the flesh!

 

If you have all that go fast stuff in a gasser then you better be going with a mechanical secondary and I would choose a 650 cfm if it was mine.
Mechanical secondaries give you the best hit when flooring that sucka and a 4777 650 carb is a pretty good size for what you got going on there.

 

Yup, I agree with Swade, a 650 double pumper will get you where you want to be, its just a choice between 3 or 4 different Holley DP's; 1 or 2 different Quick Fuel DP's or 1 or 2 different ATM Double Pumpers. If you have a traditional type hot rod the the Holley Classic would be the right one; if you have a race type combo then the Holley/QuickFuel/ATM with the billet metering blocks & race type trim; if you have a lot of showy & chrome QuickFuel or ATM offer a DoublePumper in faux chrome that is very durable.
Like I said, a 650 DoublePumper, its just a choice of which one.

 

600 Edelbrock .
Looks right on your set-up....
EZ to tune.....
Secondary air dam opens when the vacuum from the engine asks for it sooo no BIG bog.
IF you still want the wah-WAAAHHH of the back barrels popping open there's a simple way to get that too !
Take the top off the carb and you will find the counter-weights on the air dam hickey. Just drill a couple holes in the weights to make them ;lighter so it will open quicker !
The SBF engine in my (M-word) brings a big stupid grin to my face every time I nail it in 1st/2nd/3rd gear.
When cruising just keep your foot out-of-it....
6sally6

 

I use exclusively original Carter AFB carbs, work awesome on everything, if you need help contact @carbking, Jon is a wealth of knowledge on Carters and a great guy to talk to. He walked me through the dual AFBs on my convertible.