Hot Rods 471 with (2) 2-barrel Carbs

Hello!

I have a stroked 283 built for a supercharger. I am planning on running a 471 blower. All calculations for this built (engine & car) indicate a CFM range of 800-900. I wold like to run (2) 2-barrels. Because each would need to be 400-450 CFM, I am considering the Holley 2300’s. My research has not discovered anyone running this combination.

Is this a bad idea, or are there alternatives that I am not considering?

Thanks for your time and consideration!

 

I've never seen it done. If you can get two carbs to fit on there and work well, with less hassle and expense than a single carb of similar size, then go for it. Post pictures when you're done.

 

Just remember that 2 and 4 barrel carbs are rated differently.

As cool as it may look, I would probably use a single 4 just for the built in progressiveness.

 

Thanks, Jim.

This is one adapter:

 

Did you stroke it a 1/4” to make it a 307? My favorite “stroker” SBC
All kidding aside, 2 500’s or a 950 dominator... take your pick.

 

Thanks for that. I have thoroughly researched various single carb applications, and you are correct....much easier but little “cool” factor. If I could find a single air cleaner/scoop that looked decent and that wasn’t a fuel injection or multi-carb imitation I might be interested. Any pics of 471 single-carb setups would help.

 

If we did every thing the easy way we don't lean much and all look the same. Post some pictures I like your idea.

 

It’s a 1966 283 bored +0.030”. We used a new small journal Eagle 327 forged crank, Scat 6.00” rods, and custom 21cc dish Ross pistons. Milodon 4-bolt main caps. It works out to 311 CI.

 

Please, no corrupting my mind.

 

Just curious why you are considering the 2x2 vs. a 2x4? Lots of 2x4 adapters for a 471. Most are spaced for 97s, but some will fit 94s. Many prefer the 97s on a blower due to the mechanical fuel enrichment. The 94s use a vacuum power valve. But I think your idea of the two big two barrels could be made to look nice. Doesn't take much to make a carb adapter for a 471. Have fun with it.

 

Thanks for the reply. I can’t seem to find a good multi-carb combination that is in the 800-900 CFM range. I seem to either be at about 750 or 1000 CFM with various 2bbl and 4bbl combos. Although it is expensive, I do know that this Jim Inglese set-up works really well on small-bore, small displacement 471 blown engines and holds tuning well:

 

2 4412 Holley,some guy in San Jose runs them on hi 2 blownsbc

 

The Holley 4412 (500 CFM at 3 inches Hg) would be about 350 CFM at 1.5 inches Hg.

Holley used to make either a 600 or 650 CFM 2-barrel, but I don't remember the number, and don't feel like thumbing the Holley sales catalogs to find it. If it were 600 at 3 inches, then the 4 barrel rating would be approximately 425.

Stromberg made a 900 CFM 2-barrel that would be about 650 on the 4-barrel scale. And Holley made one that was roughly 550 on a 4-barrel scale, but neither will fit your intake

Jon.

 

Beatnik Bandit 303 with two 97s

I bet with a little work you could get a pair of big 97s to flow more than the advertised 250 CFM each.

It would look a hell of a lot better than a pair of Holleys

 

If you do 97s, you need four of them.

 

I was playing with the idea of adding a 471 with 2xHolleys 2bbl. to a Ford Y-block back 10 or so years ago..
I got as far as making a intake to hold 471,a 3V crankshaft drive pulley ,for twin belt drive of 471 n 1V for waterpump n gen,and found Tunnel Ram topper that was a one 4bbl on tunnel ram//by putting it up side down on 471 could be mod to mount for 2x2s or 2x4. I never finished,ran out of $ needed for a 471 snout of around 8in. long, give or take 1/2in. for 471 drive=that's what stopped me,so it all got put too back of shop. May trade it off or what ever. make offer or trade .

 

Jim, would that be an adapter like this?

 

Thanks, Jon. To run multiple carbs on a 471 that needs about 800-900 CFM, what would all of you suggest? I have included the calculations that we used for the CFM requirements below. I am learning here that they may be designed specifically for 4 barrels and are not directly applicable to 2 barrels. Is this correct?

I certainly appreciate everybody’s time, consideration, and input!!! The depth of knowledge and experience in this forum is an invaluable resource.

[(DxR)/3456] x [(B/14.7)+1]=C
D = Cubic inch displacement of the motor - 311
R = Maximum engine RPM – 6,500 to 7,000
B = Maximum blower boost - 6
C = Maximum CFM required

7,000 Max. RPM:
311 x 7,000 = 2,177,000 / 3,456 = 629.92
6 / 14.7 = 0.4082 + 1 = 1.4082
629.92 x 1.4082 = 887.05 CFM Total
887 / 2 = 444 CFM each for dual carbs

6,500 Max RPM:
311 x 6,500 = 2,021,500 / 3,456 = 584.93
6 / 14.7 = 0.4082 + 1 = 1.4082
584.93 x 1.4082 = 823.69 CFM Total
824 / 2 = 412 CFM each for dual carbs

 

1500 cfm works great on a blown 450ish inch big block, so 1000 should be about right on a blown 300ish inch small bock.

 

JimVG - I am going to offer no recommendation on carburetors for your application. The CFM answer was in my area of expertise, but aftermarket blowers are NOT in my area.

I have quite a bit of tuning experience, and cloning, Holley 4000's, (1957 T-Bird), Stromberg WW's (1957 Studebaker), Carter AFB's (1963~1964 Studebaker), and Carter YH's (Corvair); but no experience with aftermarket blowers.

However, if I were doing this, I would listen to Jim (Squirrel) in the post above this one.

Jon.

 

I ran four original 97s on a 4-71 on my 303 Olds
low compression, tiny valves, stock cam, never over 5k rpm
it did fine on the street, ok on the strip.
224 hp at the rear wheels on the dyno- roughly double stock hp

you have a very different animal

 

http://chucknuytten.com/
Might want to ask them.

 

Eventually, you're going to have to figure out what "look" you want the engine to have. What is it going in? What other parts will be on the engine? What will be the general time period appearance of the car when it's all done?

If it's kind of a mishmash of parts, then the 2 big 2bbls will fit right in. If it's a traditional looking car, then 97s would be great, or maybe even figure out how to put four 2G Rochesters on there (maybe back to back, facing sideways?). A single 750 early AFB would also work great, although you might lose a bit of performance. If you really don't care, then put a big single 4bbl on it, either a 930ish new Holley, or a Dominator, or something.

There's usually a lot more to these decisions, than first appears.

 

I ran a 471 on a 331 SBC with a 750 CFM AFB carb on my old truck for many years. It was very streetable and ran well. Here are some pics of the set up.

 

To all, thanks for these comments and reply’s. As mentioned above, I really appreciate it!

The car is a 31’ Model A Coupe. No chop or channel. Full fenders and boards. Not really trying to build traditional or period correct. As Jim mentioned above, “a mishmash of parts”. Pieces I have either had over the years or have had in various cars. I do want to run the 471, as it looks best to me on top of the 283. In consideration of everyone’s contribution, and thinking about the new build and the investment I have to-date, I may just run a single 4bbl that’s boost referenced (or do it myself) for an extended break-in period. Once the rest of the build is dialed in I can do something more unique with multiple carburetors. The only exception would be the dual Weber set-up that is built specifically for the 471, but that currently is cost prohibitive. I will start another thread on the whole build, as I have a number of other unrelated questions. I have included a few pics....

 

I made this billet one piece plate for my brothers flathead for 2300. we used holley 7448 carbs the I cut the air horn off, (gives more flow) plus cut the back off to fit them on the 4-71. I also boost referenced the power valves. Don't have it running or anywhere close to run, but I think it will do just fine on our 286 incher.

 

@Flatrod17

Shhhh, don't say 'billet' here. Nice piece, though!

Are you going to blend the steps at the inlet of the blower?

 

Flatrod17, that looks nice! I prefer my aluminium hot rod stuff bead blasted with some glass beads and a coat or two of Gibbs. But maybe I am lazy.

 

Jim, what specific glass beads are you using? Can you post a pic of a piece you have applied this method to? Thanks!