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Technical Cam choice for Blower on Smallblock

Discussion in 'Traditional Hot Rods' started by ace high, Oct 22, 2017.

  1. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    I’d like some thoughts on which cam would be better for a Chevy 350 with 8.5:1 CR with stock cast pistons and a GMC 471 blower making 4 lbs boost. Strictly a street car, but I want that occasional burst of WOT extra HP but I don't want to destroy the engine.
    I’m thinking of two different cams
    First cam would be 114 Lobe Separation, with 222 duration @ .05 and .450 lift
    The second cam is 112 Lobe separation, with 202 duration @ .05 and .400 lift
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,499

    gimpyshotrods
    ALLIANCE MEMBER

    The first one.
     
    loudbang likes this.
  3. AngleDrive
    Joined: Mar 9, 2006
    Posts: 807

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    I have a Crane H-278-2 in my 4-71 283. 222/234, lift .467/.494, lobe separation: 114
     
  4. paul55
    Joined: Dec 1, 2010
    Posts: 3,308

    paul55
    Member
    from michigan

    I was doing the same thing and the cam I was looking at was a split profile cam. 214/224 duration and .445/.465 on the lift.
     
    loudbang likes this.

  5. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Do you have stock pistons or forged? About how much boost do you have?
     
  6. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Seems like the 114 LS is the way to go.
     
  7. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    I'm hearing that that longer exhaust duration similar to computer control engines is a plus for blower motors.
     
  8. AngleDrive
    Joined: Mar 9, 2006
    Posts: 807

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    Forged, about 8lbs. It's going in a 41 Ford p/u with crash box and banjo, so I won't be using the HP even though I have lots of spare transmissions and rear ends. You really need to stay away from too much overlap.
     
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  9. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    I'm kind of concerned about my stock pistons, rods, and crank. I'm hoping I'll be OK where I'm underdriven
    with 4 lbs boost.
     
    loudbang likes this.
  10. wingedexpress
    Joined: Dec 24, 2006
    Posts: 894

    wingedexpress

    4lbs shouldn't be a problem, just control any detonation with good timing and gas.
     
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  11. Deuces
    Joined: Nov 3, 2009
    Posts: 18,533

    Deuces
    Member
    from Michigan

    Got pics of the blower assembly and intake????
    Please post away...... Thanks!!!!! :)
     
  12. AngleDrive
    Joined: Mar 9, 2006
    Posts: 807

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    My 283 was a power pack motor with small chamber heads. I found a set of 57 2 barrel 64 cc heads to lower the compression ratio some. Ignition is vertex mag. I'll run 90 octane non ethanol with a shot of octane booster. Carb is 50 caddy wcfb
     
  13. DDDenny
    Joined: Feb 6, 2015
    Posts: 13,648

    DDDenny
    Member
    from oregon

    Belt drive or Gilmer?
     
  14. AngleDrive
    Joined: Mar 9, 2006
    Posts: 807

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    I have 60% of a three belt drive and all of a 2" gilmer. Would like to run the three belt set up but what i need might not be worth the cost to complete. Since it is a early 60's style build either one would be period correct.
     
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  15. buffaloracer
    Joined: Aug 22, 2004
    Posts: 800

    buffaloracer
    Member
    from kansas

    Watch the timing very carefully.
    Pete
     
    loudbang likes this.
  16. pitman
    Joined: May 14, 2006
    Posts: 4,959

    pitman

    Forged, or cast crank? Had a 300hp 327, was bullet-proof w/the right hardware.
     
  17. squirrel
    Joined: Sep 23, 2004
    Posts: 46,708

    squirrel
    Member

    do you mind if I ask for the basics, such as transmission type and rear gearing?

    The fact that you are running cast pistons means that you won't want to rev it too high, and either of those cams would be ok with that.

    First cam if you have a little bit of gear/stall, second cam if it's a stock drivetrain.
     
    saltracer219 likes this.
  18. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Gilmer
     
  19. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Cast
     
  20. ace high
    Joined: Dec 15, 2007
    Posts: 210

    ace high
    Member

    Trans is a Turbo 400 ; Rear ratio 3.08; 2100 stall speed
     
  21. squirrel
    Joined: Sep 23, 2004
    Posts: 46,708

    squirrel
    Member

    I think either cam would work ok.
     

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