Cam bumper

Discussion in 'Street/strip 400/430/455' started by jhonjhon, May 3, 2020.

  1. ranger

    ranger Well-Known Member

    Nice theory, but was used on both odd-fire and even-fire.

    Ranger
    Aiken, SC
     
  2. 87GN_70GS

    87GN_70GS Well-Known Member

    That is correct, they are tapered and crowned. However, they are not all the same direction, they alternate fore and aft, as to keep the force on the cam neutral (except for #3 exh on the 3.8 which is the only one that does not alternate as there was a blueprint error but that is another story)

    On the V8 they are all in the same direction
     
    Mark Demko likes this.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Ahh, very interesting.
     
  4. 87GN_70GS

    87GN_70GS Well-Known Member

    The article is about the V8

    The V6 had the cam bumper
     
    ranger likes this.
  5. ranger

    ranger Well-Known Member

    Yes, but the question is why? We are not talking roller lifters. Rather, flat-tappet. And why did Buick engineers even bother to include a "seldom-used" bumper that was cast into the timing cover. Added cost for nothing? Doubt it. And I have seen a few V-8s where it was obvious the cam did, at least occasionally, come into contact w/ the bumper.

    Ranger
    Aiken, SC
     
  6. 87GN_70GS

    87GN_70GS Well-Known Member

    The only thing I can think of is that if for some crazy reason the engine were to run backward, all those forces now act to push the cam out of the block. A bumper would limit that
     
    Last edited: May 28, 2020
  7. ranger

    ranger Well-Known Member

    Scott, I think you are missing a word in your post, first line? But the bumper was on the old odd-fire, as well as the newer even-fire, so we can't blame asymmetrical vibrations for the reason for the bumper, as I think one person possibly opined.

    Ranger
    Aiken, SC
     
  8. 87GN_70GS

    87GN_70GS Well-Known Member

    Thanks, corrected
     
  9. Mark Demko

    Mark Demko Well-Known Member

    IIRC, one of the lobes on the V6 cams had a reverse taper, I don't remember why tho:(
     
  10. Mark Demko

    Mark Demko Well-Known Member

    Ahaa! Maybe that was the reason!
     
  11. FJM568

    FJM568 Well-Known Member

    #3 exhaust lifter bore on 3.8 v6 was machined in wrong position and almost centered on cam lobe. With stock lower lift cams and stock valve springs it wasn't that big of an issue. But with higher lift aftermarket cams and stiffer valve springs, that particular lifter had trouble spinning and not breaking in properly.

    Don't ask how I know...x3. :mad: LOL

    That's why most go with roller cam conversions.
     
    Mark Demko likes this.
  12. Mark Demko

    Mark Demko Well-Known Member

    HAHAHA me too!
    For me it started with the KB turbo cam.... went flat.
    Then the Budget cast roller...…. crumbled apart.
    Been on the PTE Billet roller since '05 no issues.
     
    FJM568 likes this.

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