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Technical Roller Tappets and flat tappet cams

Discussion in 'The Hokey Ass Message Board' started by porknbeaner, Oct 2, 2021.

  1. OK so here is the deal. I am getting ready to screw a motor together. The block is new enough to be a roller block but it is still a motor that we would use in a HAMB friendly car.

    That was the back story. ^^^^^

    Now the discussion came up about using roller lifters on a flat tappet cam. This was just a general discussion. Before someone gets all self righteous about this question bear in mind that roller cams have been around since gawd knows when.

    Anyway I am no expert on the subject and have not tried it yet (I have run roller moors since as long as i can remember). But my thoughts are that the cam shaft and the lifters will not care. I could be wrong.:eek::D

    So what are your thoughts or better yet experience in this subject.

    Please play nice and don't fight. Remember drama is your enemy.
     
    427 sleeper and Deuces like this.
  2. That’s a hell of a question beaner. My concern would be some flat tappet cams have the lobes machined slightly tapered to control end thrust. That may cause one side of the wheel on the roller to dig in? Other then that I can’t see why it wouldn’t work other then losing the more aggressive ramps we can get away with on roller cams.
     
    427 sleeper, Deuces and ekimneirbo like this.
  3. I would have thought that however a flat tappet cam is ground to induce lifter rotation would not work with roller lifters. The roller lifters would want/need a flat surface.
     
  4. oooops I screwed that one up. Sorry.:oops:
     
    Deuces likes this.

  5. Flat tappet cam lobes have an angle on their surface to spin the tappets, roller cam lobe surfaces are ground parallel to the cam.
     
  6. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,467

    Elcohaulic
    Member

    +2..
     
    gimpyshotrods, Deuces and Joe Travers like this.
  7. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,416

    oldiron 440
    Member

    Cam profiles are completely different between the two types of cams.
     
    Elcohaulic, gimpyshotrods and Deuces like this.
  8. Budget36
    Joined: Nov 29, 2014
    Posts: 7,249

    Budget36
    Member

    Is it roller lifters or roller rockers? I assume rockers?
     
    Deuces likes this.
  9. Deuces
    Joined: Nov 3, 2009
    Posts: 21,299

    Deuces
    Member
    from Michigan

    If using roller rockers with a flat tappet cam, then yes!
    If using roller lifters on a flat tappet cam, no way!....
     
    Budget36 likes this.
  10. There's also a metallurgy issue; roller lifter rollers/cams are made of steel, flat tappet cams are cast iron. The steel will eat up the cast iron. If cast iron would work, the OEMs would use it but they don't.
     
    427 sleeper likes this.
  11. blowby
    Joined: Dec 27, 2012
    Posts: 7,957

    blowby
    Member
    from Nicasio Ca

    And flat tappet cams lobes are offset to the lifter bore. I'm guessing roller cams are not.
     

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