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the minimum amount of carbs on a 671 (2 brrl)

Discussion in 'The Hokey Ass Message Board' started by deadbeat, Dec 1, 2011.

  1. deadbeat
    Joined: May 3, 2006
    Posts: 655

    deadbeat
    Member

    Hey guys.First of all I have tried to search on here & came up with cfm's etc for Stromberg 94 carbs etc,but couldnt find any on what is the minimum amount of 94 carbs that I can run on a 671.
    Ive got 3 cherry 94 carbs & a 671 to run on a stock 390 FE engine.My question will that be enough or will I need to find more as they are getting harder to get.
    Again apologies if this has come up before.
    Cheers
     
  2. Blue One
    Joined: Feb 6, 2010
    Posts: 11,459

    Blue One
    ALLIANCE MEMBER
    from Alberta

    The purpose of a blower is to move air. If you are expecting to move lots of air and make boost and power, you need something which will flow air too.

    You will not be able to mount as many 94s as you would need to keep up with the airflow demands of a 6-71.

    Unless you can come up with a way to mount 15 of them and make it look good :rolleyes:
     
  3. The more you choke the inlet the hotter your charge will be. I wouldn't think that 3 94s would do it but there is no doubt someone here that has an equation that will help. I wouldn't run less than a pair of 650s if it was me. That is probably a little on the weak side.

    I guess to really know you need to know how much air the 671 pushes and then try and match your cfm rating to that.
     
  4. Ned Ludd
    Joined: May 15, 2009
    Posts: 5,026

    Ned Ludd
    Member

    It all depends on what speed you're running the 6-71 - and that needs to match the engine displacement and static compression ratio. Theoretically you can run a single 2bbl on a 6-71 if you run it slowly enough on a small engine. You would have to compensate a bit for pressure leakage at such low speeds, but on the other hand pressure/thermal issues are likely to be minimal.

    You can run a 6-71 on a stock-compression 750cc motorbike engine if you underdrive it 94% ...
     


  5. Ned

    You analogy reminds me of when I was a kid I knew a guy that said you could pull a freight train with a washing machine motor if you had enough gears.

    Sorry I am way off base here but it just made me chuckle, reminded me of a long lost friend.
     
  6. the way to figure it out is determine the cfm at red line the double it. i have a 354 hemi that is blown on the street. it is run at 2 under and makes 12lbs of boost. my redline is 7500 rpm. i run eight 97s and it runs great. if i could get two more on the manifold i would put them on. if you dont get enough gas in the engine under boost the engine will lean out. in severe cases detonation will occur. you will know it happened after the intake side of your pistons are missing and your rings loose their tension and a few bearings are flattened not joking 3 carbs on a blown 390 is just not enough.
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    four 97s work good on a 3-71 on a flatty....so I'd say you're about 5 carbs away from what you want on a 6-71 on a big block
     
  8. Actually most of the time when you see stromburgs on a blower you see 6.

    I raced stromburgs about 40 years ago, thay look neat but they really are not much of a carb. If I were huffing a 390 I would be running an induction setup like squirrel.
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    The familiar holley 4 bbl was introduced the year before the FE engine, does that tell you something?
     
  10. deadbeat
    Joined: May 3, 2006
    Posts: 655

    deadbeat
    Member

    Hey thanks alot guys,really appreciate the input.I have just come across another 3 carbs but they nead rebuilding.
    The only reason that im going with a 671 as I have a blower intake which Ive had for years & was thinking of using it & have just bought a 671.I also run 3 stromys on my FE at the moment so I thought I could "cheat" by using these carbs/linkages as well.
    Again thanks guys for the input.
     
  11. oj
    Joined: Jul 27, 2008
    Posts: 6,454

    oj
    Member

    Very informative thread, thanks.
     
  12. Is it for show, or go, or both? Underdrive it and run your 3 if you just want a blower motor. I don't recall you mentioning a horsepower goal...?
     
  13. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,625

    Atwater Mike
    Member

    Air 'Flow'? Wait a minute, that means the air has to have an outlet...Fluid dynamics state that when air is moving, it must have an exhaust volume 1.5X the unrestricted intake.
    But this air is under pressure! There would be a manifold pressure gauge, (as there's no manifold vacuum, there is pressure (6X71 C.I. volumetric) so the potential inlet of the 390 is the quotient of 1.5+ of the potential intake volume? I doubt it.

    To prove my point, if the 390 was a 'bottomless pit' of desired gradient, it would be 'puffed-up' at the valve covers, like those 6-71s did to all the Chryslers!

    See?
     
  14. deadbeat
    Joined: May 3, 2006
    Posts: 655

    deadbeat
    Member

    No,just a stock motor in a 60's style 1930 Tudor that im building atm.I have been collecting intakes for FE's for years & thought I would best start using them.Im getting sick & tired of moving them around my shed,,lol.:eek:.Later I will build a strong motor,,,cheers
     
  15. slickhale
    Joined: Dec 19, 2010
    Posts: 772

    slickhale
    Member
    from Phoenix

    if you run out of room in your shed for those intakes you can give me as many as you like, i'll even pay shipping:D
     
  16. 31modelo
    Joined: Apr 9, 2006
    Posts: 1,141

    31modelo
    Member

    If you would like to run 3 94's you should look for 2100's or 2110's. They both move a lot more fuel than the others. Yes like the rest have said all depends on how it's setup.
     
  17. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    The minimum number of 97's you can run on a 6.71 is one. Wont make any power, but you didnt ask how much power it would make, so there you go.
     
  18. deadbeat
    Joined: May 3, 2006
    Posts: 655

    deadbeat
    Member

    Mate you'd be surprised as to how many times I have heard that :)
    Aint no point having them if you aint going to use them

    Thanks bud.Finding good ones are a challenge down here

    QUOTE=falcongeorge;7197219]The minimum number of 97's you can run on a 6.71 is one. Wont make any power, but you didnt ask how much power it would make, so there you go.[/QUOTE]
    Yeah I dont want it so its un streetable as I will be driving the pants of it as I do with all my cars,thanks for your input
     
  19. I changed from 94's to Stromberg WW's and they are much easier to find & flow about 30% more than a Ford 94 or Strom 97. and about 1/8 to 1/2 the price.

    They are unfortunantly 4 bolt base, but the front 2 bolts line up with the 3 bolt base. You have to radius the manifold openings to allow the butterflies to fully open but that's about 3/16 inch (.8 CM if I calc correctly)
    I'm using 6 Stromberg WW's Edelbrock manifold on a 428 FE with Dashman spacers for linkage clearance.

    Stromberg WW's were used by Ford Chrysler Desoto & even GM until the mid 1960's.

    Movin/on
     
  20. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,207

    Shaggy
    Member
    from Sultan, WA

    Why go 94's anyway, there are bigger carbs of the same family all the way up to 1 3/16" venturi or possably bigger and best of all, they are typically cheaper too!!


    Oh, i didnt notice your location....
     
  21. dashman
    Joined: Apr 15, 2009
    Posts: 774

    dashman
    Member
    from Viroqua WI

    Just as a side point, I'm working on a small run of blower tops for the 6-71 that will be an 8x2 setup. It will have the spacing to run Holley 94's or Stromberg 97 carburetors. Or if you want a little more it could fit 8 small Rochester 2G carbs, which would be crazy, but the room is there.

    Dashman's Hot Rod & Speed Parts www.dashman.net
     

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