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Technical Flathead V8's, cams and the RPM Effects?

Discussion in 'The Hokey Ass Message Board' started by tjm73, Jul 24, 2025 at 12:14 PM.

  1. tjm73
    Joined: Feb 17, 2006
    Posts: 3,655

    tjm73
    Member

    What RPM effects come with the commonly used flathead cams? Like which cams shift the powerband up the tach and by how much?

    OEM cams check out around 3500-4000. Do any of the streetable cams carry out to 4500-5000?
     
  2. 19Fordy
    Joined: May 17, 2003
    Posts: 8,313

    19Fordy
    Member

  3. tjm73
    Joined: Feb 17, 2006
    Posts: 3,655

    tjm73
    Member

    I found a hot rod article with a whole mess of intake dyno'd. 4 barrel, dual carb, triple carb. The 284 CID dyno engine had a H&H spec'd custom 280 advertised cam and it peeked in the hp's right around 4500 with all intakes.
     
  4. stubbsrodandcustom
    Joined: Dec 28, 2010
    Posts: 2,563

    stubbsrodandcustom
    ALLIANCE MEMBER
    from Spring tx

    The cam really isn't the major hold back on a flatty, it's the valves and configuration.

    My ISKY 1007b cam runs out about 4500 but pulls like a freight train in the mid range. I'd rather have torque I can use and enjoy than HP.

    Opening up intake valve to a larger size and you are on your way to making it better but fighting the exhaust all the way out. Porting and smoothing are two things to improve, but still, by nature they are hard to get to spin high without OHV conversions. The center port is a known HP killer on the exhaust.

    Good springs, some mild work, and probably any isky cam over a 88 will net you 4500, only real cams to push higher were the 400 jr and above.

    isky cam spec.JPG
    Making HP on a flatty is how much money you want to throw in the wind. My recommendation is to find a cam that sounds good and make a good stroker motor and if you still have money, bolt a HUFFER on top!
     
  5. tjm73
    Joined: Feb 17, 2006
    Posts: 3,655

    tjm73
    Member

    I firmly believe a good street engine only really needs to spin to about 5000 rpm. My daily driver is a 180hp/190ft-lb turbo 3 cylinder. I only use about 2/3's of it's hp but peak torque is around 3000 rpm and I work all 190 ft-lb all the time. But when I want 5000 from time to time, it's a little gutless.

    A flatty with 125-140 hp and with 200 ft-lb that I can access with a T5 would do just fine.
     

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