Oil pump clearance question

Discussion in 'Street/strip 400/430/455' started by Houndogforever, Dec 3, 2019.

  1. Houndogforever

    Houndogforever Silver Level contributor

    All my searching comes up with lots of information on the oil pump end clearance, but I cannot find ANYTHING telling me about wall clearance to the pump gears?

    How large a feeler gauge should I be able to fit between gear and pump housing diameter?

    I'm trying to determine if this used TC I have is good because I will then sell it since I bought a TA cover.
  2. johnriv67

    johnriv67 Well-Known Member

    Don't quote me, but I believe less than .010 is desired. Other guys who know more will chime in
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    ranger likes this.
  4. Schurkey

    Schurkey Silver Level contributor

    From a certain perspective, since you can't change tip-to-wall clearance it doesn't really matter unless it's so huge that the pump housing is unusable.

    Ideally, someone would sell oversize gears in +002, +.004, etc. sizes.
  5. 87GN_70GS

    87GN_70GS Well-Known Member

    Could have the gear pockets bored out then fabricate some sleeves out of tubing and press in place
    BuickV8Mike likes this.
  6. Schurkey

    Schurkey Silver Level contributor

    I thought about that. I think that's a dangerous route. The two tubes (sleeves) would have a fair amount of overlap, which has to be bored-out to fit the gears. With that much of the tube (sleeve) gone, there's little press-fit to keep the things in place.

    I think it'd be easier to build slightly oversize gears to fit into a worn--or freshly-reamed gear pocket in the original cover. 'Course, making gears is no trivial task unless you're set up for that sort of work.

    Far as I'm concerned, making the gear pocket out of the same cast-aluminum as the timing cover was a big mistake. The hotter the engine gets, the more the housing expands, and the greater the leakage around the gear tips. An iron pump housing--or an iron insert in the aluminum timing cover--would have been a better, more durable, but far more expensive solution.
  7. Houndogforever

    Houndogforever Silver Level contributor

    I wonder if you could have existing gears flame spray welded up and regrind slightly larger?
  8. Schurkey

    Schurkey Silver Level contributor

    You'd only have to lengthen the gear tip. The flanks of the gears--the parts that touch each other--would stay the same.
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Years ago, they were using spray coatings to repair the pocket. That might be an option for an other wise good TC?
  10. Schurkey

    Schurkey Silver Level contributor

    I suppose an anodizing process could add a couple thousandths of wall thickness. I don't know what could be "sprayed on". Interesting process.
  11. BuickV8Mike

    BuickV8Mike SD Buick Fan

    Hard anodize is also a little thicker and provides better wear resistance.
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  13. Schurkey

    Schurkey Silver Level contributor

    Seems to me that either Teflon or hard anodized coating would do a fine job of preventing cooling system corrosion (at least until it got scarred by bolt threads or slipped wrenches or water pump impeller interference or whatever.)

    Might be cool to drop the entire front cover into the Dip.

    Edelbrock sells BBC aluminum cylinder heads intended for marine applications. The water-jacket and non-machined exterior has some sort of anodizing that prevents corrosion from the raw-water cooling, but still allows heat transfer.

    Both the oval and rectangular port heads are hard-anodized to protect the aluminum in the harsh marine environments.

    Hard anodized black to protect the aluminum in the harsh marine environment.
    Last edited: Dec 5, 2019

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