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Hot Rods 471 with (2) 2-barrel Carbs

Discussion in 'The Hokey Ass Message Board' started by JimVG, Jul 11, 2020.

  1. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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!
     
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  2. squirrel
    Joined: Sep 23, 2004
    Posts: 46,358

    squirrel
    Member

    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.
     
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  3. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 2,498

    GearheadsQCE
    Member

    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. :D
     
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  4. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    Thanks, Jim.

    This is one adapter:
    3844DCF5-E27F-40F1-A74C-34D57D0C6EE2.jpeg
     
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  5. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,677

    jimmy six
    Member

    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.
     
    redo32 likes this.
  6. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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.
     
  7. 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.
     
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  8. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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.
     
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  9. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,164

    Jmountainjr
    ALLIANCE MEMBER

    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.
     
  10. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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: 99D6C57C-DB27-493A-B523-F80BCE9A5259.jpeg
     
  11. sdluck
    Joined: Sep 19, 2006
    Posts: 2,475

    sdluck
    Member

    2 4412 Holley,some guy in San Jose runs them on hi 2 blownsbc
     
  12. carbking
    Joined: Dec 20, 2008
    Posts: 2,830

    carbking
    Member

    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.
     
  13. Paul
    Joined: Aug 29, 2002
    Posts: 14,886

    Paul
    Editor

    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

    Beatnik-Bandit-3.jpg
     
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  14. squirrel
    Joined: Sep 23, 2004
    Posts: 46,358

    squirrel
    Member

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

    97.jpg
     
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  15. Moriarity
    Joined: Apr 11, 2001
    Posts: 18,576

    Moriarity
    SUPER MODERATOR
    Staff Member

  16. dana barlow
    Joined: May 30, 2006
    Posts: 3,956

    dana barlow
    Member
    from Miami Fla.
    1. Y-blocks

    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 .
    PDR_2244.JPG
     
    Last edited: Jul 25, 2020
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  17. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    Jim, would that be an adapter like this? BA56BF92-96EC-48A3-B6D0-97878C015D27.jpeg
     
  18. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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
     
  19. squirrel
    Joined: Sep 23, 2004
    Posts: 46,358

    squirrel
    Member

    1500 cfm works great on a blown 450ish inch big block, so 1000 should be about right on a blown 300ish inch small bock.
     
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  20. carbking
    Joined: Dec 20, 2008
    Posts: 2,830

    carbking
    Member

    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.
     
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  21. Paul
    Joined: Aug 29, 2002
    Posts: 14,886

    Paul
    Editor

    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
     
  22. Pontmerc
    Joined: Jul 13, 2013
    Posts: 100

    Pontmerc
    Member
    from Finland

  23. squirrel
    Joined: Sep 23, 2004
    Posts: 46,358

    squirrel
    Member

    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.
     
  24. Russco
    Joined: Nov 27, 2005
    Posts: 4,131

    Russco
    Member
    from Central IL

    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.

    8CEEC441-7941-4F8B-AC44-7594E2A5E4F3.jpeg 00D66214-FD92-44B7-8141-62CDEBD8813E.jpeg 304CCB9A-8A02-44FC-86B8-991A9EB86FF9.jpeg 38BB600B-1322-44E1-B2B5-17892A08C671.jpeg
     
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  25. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

    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....

    ACA8A350-292A-41F5-9946-2FBDFCFD0BF7.jpeg 2EC22C6F-368A-4D43-9080-170C43AB2772.jpeg 8D906C24-B3F5-4C89-8711-922DD8AA1EF5.jpeg A3086730-B7E8-4309-AF61-EEF23E1E41A1.jpeg D2B7FC7A-81F7-451D-A813-EEF1D4282D95.jpeg 27EC2BC7-401D-4C2D-A48D-F0964A80B631.jpeg 4148755-77d2c552f244821315355ecadcb3fcc3.jpg
     
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  26. Flatrod17
    Joined: Apr 25, 2017
    Posts: 54

    Flatrod17
    Member

    plate.jpg 4-71.jpg boost tube.jpg 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.
     
  27. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 2,498

    GearheadsQCE
    Member

    @Flatrod17

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

    Are you going to blend the steps at the inlet of the blower?
     
  28. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,164

    Jmountainjr
    ALLIANCE MEMBER

    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.
     
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  29. JimVG
    Joined: Nov 6, 2016
    Posts: 34

    JimVG

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

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