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Thread: Oil Pump Gear

  1. #1

    Default Oil Pump Gear

    Anyone know how many teeth are on the oil pump shaft gear?
    SFC, HQ,129th Sig Co, PAARNG, Vietnam Era

  2. #2

    Default

    No, but why do u ask?
    68 M-715 MVPA #2710

  3. #3

    Default See My Other Thread

    Quote Originally Posted by george walker View Post
    No, but why do u ask?
    Mostly academic but see my thread about timing. My distributor is off timing and I can't get anymore adjustment. I think someone had the oil pump out and did not align it when reinstalled. This in turn messes up the distributor. I want to figure how many degrees off it is.
    SFC, HQ,129th Sig Co, PAARNG, Vietnam Era

  4. #4

    Default

    Oh, well if its off just bring #1 cyl to tdc comp. then make sure rotor is at #1 in the dist, if not pull it out(dist) an move it until it is or is very close. at that point it will be close enough to get timing set. if you have to move the dist more than a couple teeth you may have to also move the oil pump shaft a bit to keep it aligned w/ the dist shaft also.
    68 M-715 MVPA #2710

  5. #5
    Join Date
    Dec 2003
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    SF Bay Area, CA
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    499

    Default

    Unfortunately the gear is not on the distributor shaft, it's on the oil pump. The dist shaft just has a blade at the end.

  6. #6
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
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    11,520

    Default

    Correct Hiker...and dont forget that one end of that blade is wider than the other so it only fits correctly 1 way...cant even put it in 180 degrees off.

    There is a procedure for the pump install...its in the -34 manual...or...

    Roll the engine to tdc on compression stroke...look where the rotor is pointing on the cap and put the #1 wire in that location...if it is off by much, then you will need to do the oil pump reindexing.

  7. #7

    Default 12?

    I haven't pulled the distributor or pump but based on pictures, drawings and doing the math, I think the oil pump has 12 teeth. It must be divisible by 6 and also divide into 360 equally. It holds out for my timing error.
    SFC, HQ,129th Sig Co, PAARNG, Vietnam Era

  8. #8
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
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    Default

    I get the 360 division but why 6?

    I did see one out a few years ago...wish I had counted...anyway, 12 isnt out of the question at all...

  9. #9

    Default

    Quote Originally Posted by rboltz View Post
    I think someone had the oil pump out and did not align it when reinstalled. This in turn messes up the distributor. I want to figure how many degrees off it is.
    You can verify this by removing the distributor and looking down the hole with a flashlight. With the timing marks lined up, the slot in the oil pump should be at 3 and 9 o'clock Even when 180 out the slot should still be fore and aft just offset up or down. This text suggests the blade on the distributor and the slot in the pump is offset from center. I've never seen one -- Just going by the text.

    The below text is from the TM 9-2320-244-20 Organizational Maintenance Manual.

    c. Ignitor. If a new ignitor is being installed, or if camshaft has been rotated with ignitor removed, rotate crankshaft until timing line on timing case cover is aimed with “0” mark on scale on vibration damper and engine is in the number 1 firing position.
    (1) Look down the ignitor shaft hole with a light and observe the position of the slot in the end of the oil pump shaft. It should be at the 3 and 9 o’clock position with the narrow side of the shaft on top.


    Last page of this link.
    http://www.m715zone.com/vb/view.php?pg=20chap2-14



    Also this link supports your theory of twelve-tooth gear and the potential for the timing to be off. This is not the same oil pump as the 230 but does have the offset slot for the distributor. This one is driven from the cam so the gear ratio is probably 1:1 where the 230 is driven by the crank and should be a 2:1 crank to distributor.

    The oil pump is driven from the camshaft by means of a spiral (worm) gear. The distributor in turn is driven by the oil pump by means of the distributor shaft which engages a slot in the end of the oil pump shaft. Because the tongue and the slot are both machined off center, the two shafts can only be meshed in one position. Since the position of the distributor shaft determines the timing of the engine, and is controlled by the oil pump shaft, the position of the oil pump shaft with respect to the camshaft is important.

    http://www.film.queensu.ca/cj3b/Tech...orInstall.html

  10. #10
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
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    11,520

    Default

    The 230 ha the oil pump driven off a worm gear on the crank...not the cam...

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