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Technical 4-71 on a 327

Discussion in 'The Hokey Ass Message Board' started by 1twisted1, Mar 17, 2019.

  1. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Ok as some might have seen in my other post, I'm the proud new owner of a GMC 471 with Cragar V-belt Drive and SBC Wieand Intake.

    This setup is going into my 52 Chevy build that I was planning on running a 283 in. So now the reason for this post, the 283 block I was planning on using is cracked and not worth fixing.

    How would the 4-71 work on a 327 30over so 331?, My fear is it would be to small for the motor. Should I just find another 283 to use?
     
    Last edited: Mar 17, 2019
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  2. The 4-71 was the blower most commonly used on the street way back when. It is more then enough blower for the average small block.
     
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  3. 4 x 71 = 284 cu inches. What's the ratio on your drive setup? Sounds like that little sweetheart would be great, driven 1:1 on your street 327!
     
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  4. Deuces
    Joined: Nov 3, 2009
    Posts: 23,754

    Deuces

    Spin the blower faster with a smaller blower pulley to gain more boost....
     
    Last edited: Mar 17, 2019
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  5. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Drive ratio just happen to be 1:1 with my pulley setup. 20190316_173416.jpg
     
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  6. AngleDrive
    Joined: Mar 9, 2006
    Posts: 1,145

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    What are you planning to do with this car? Street, drag, both?
     
  7. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Car will be a vintage 50'-60's street car, so only drag racing will be light to light
     
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  8. Fordors
    Joined: Sep 22, 2016
    Posts: 5,373

    Fordors
    Member

    Is it just the photo, or is the crank pulley a smaller diameter than the blower pulley? It looks like those underdrive the blower. What are diameters of pulleys?
     
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  9. AngleDrive
    Joined: Mar 9, 2006
    Posts: 1,145

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    Ok, combustion chamber size and cam choice plus cubic inches have a direct effect on boost. You are going to be in the 8 to 1 range with your 1 to 1 set up. I'll get my folder out and give you the specs on what I did to my 283 with a similar set up.
     
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  10. AngleDrive
    Joined: Mar 9, 2006
    Posts: 1,145

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    Thought the same thing
     
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  11. Russco
    Joined: Nov 27, 2005
    Posts: 4,327

    Russco
    Member
    from Central IL

    I ran that exact set up (471 on a 331 SBC weiand intake but with a 2” Gilmer belt instead of the v belt drive you have) for many years. 6% underdriven sometimes then 6% overdriven at others, it ran pretty good, ran on pump gas, was very streetable and a blast to drive.
     
  12. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Pulleys are the same size 6.5" 2019-03-17 20.12.16.jpg 20190317_200311.jpg
     
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  13. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    That sir is 100% BAD ASS!!!!!!! the fact your auto-crossing that bad boy is just flat out COOL!!!!!!!
     
    Last edited: Mar 17, 2019
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  14. Fordors
    Joined: Sep 22, 2016
    Posts: 5,373

    Fordors
    Member

    The camera might lie, but the tape measure will not.
     
  15. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Well thits build just keeps getting better, went and picked up the motor and 400 bucks and 2hrs later I'm home.

    GOTTA love what I found as a head number

    20190317_201417.jpg 20190317_195938.jpg .
     
    Last edited: Mar 17, 2019
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  16. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Thank You Sir, That would be greatly appreciated.
     
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  17. belair
    Joined: Jul 10, 2006
    Posts: 9,013

    belair
    Member

    Want, want, want. Congrats.
     
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  18. catdad49
    Joined: Sep 25, 2005
    Posts: 6,401

    catdad49
    Member

    Caprice............? No Way!
     
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  19. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Looks to be a nice 327/275 motor from a full size.

    Block
    3858174 - BLOCK CASTING NUMBER.
    E206 - BLOCK CASTING DATE
    F0607HCH - ENGINE ASSEMBLY DATE/SUFFIX CODE

    Heads
    3890462 - HEAD CASTING NUMBER
    F16 - HEAD CASTING DATE
     
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  20. J. A. Miller
    Joined: Dec 30, 2010
    Posts: 2,057

    J. A. Miller
    ALLIANCE MEMBER
    from Central NY

    Those are good heads - they came with either 1.94 or 2.02 valves. You can't tell until you measure them. My 327/275 motor had the 1.94s. Great little engine - be greater with that 4-71!
     
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  21. catdad49
    Joined: Sep 25, 2005
    Posts: 6,401

    catdad49
    Member

    Hey twisted, it's kind of any running joke around here that "any" 327 came out of a Corvette! With the right components and compression ratio this one should serve you well with that 4-71. Good Luck.
     
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  22. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Yup 1.94s and by the looks of it the motors never been apart . Still stock bore & pistons 20190318_154748.jpg 20190318_154417.jpg
     
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  23. Nice score STOCK bore even...….
     
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  24. I read that on the internet also

    ALL 327's listed was from a Vette...

    If its on the internet it must be true !
     
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  25. lumpy 63
    Joined: Aug 2, 2010
    Posts: 2,603

    lumpy 63
    Member

    It's been apart for sure because the steel shim head gaskets are long gone...But if it's standard bore it's a great find:cool:
     
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  26. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Would these be the gaskets your referring too? 20190319_155507.jpg 20190319_155520.jpg
     
    Last edited: Mar 20, 2019
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  27. patsurf
    Joined: Jan 18, 2018
    Posts: 1,025

    patsurf

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  28. 1twisted1
    Joined: Nov 26, 2011
    Posts: 184

    1twisted1
    Member

    Stock as they come. Little under due to carbon. Cylinders 8 & 2
    20190319_192649.jpg 20190319_192703.jpg
     
    Last edited: Mar 19, 2019
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  29. 19Eddy30
    Joined: Mar 27, 2011
    Posts: 2,314

    19Eddy30
    Member
    from VA

    1-1 set up with 4-71 on 330 cid will be around 5 psi of boost , you will need 850-950 cfm's of carb
    Draw threw blower Like cfm's ,
    your Boost plus static compression ratio under 13-1 you will be ok on pump 93-94 ,
    Its all in how you tune .
    No need to O ring (good fepro gasket#1004) might be 400 gasket , but a felpro wire ring
    Arp bolts or studs
    nor duble key way , small 327 Balancer hub ,belts will probably slip even with 3
    Mild port clean up , those heads are 1.194
    Small cam change ,
    About 32-33 total degrees with 15 -23 degres at idle
    2-1/2- to 2-3/4 inch exhaust.
    I have ran 10-5 forged pistons with 8 pounds boots
    8mm belt ( no slip ) & No blower hub . Cast crank
    Over 20,000 miles .
    On OLD pump formula /blend but not on new blend .
    3,200 pound car 107 mph 1/8 @ 6:60 8 inch wide Radial tire 28 tall 3:55 gear 2,200-2,500 stall
    6,500rpm's
     
    Last edited: Mar 19, 2019

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