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Thread: Knucklehead springs

  1. #1

    Knucklehead springs

    Greetings
    I was fortunate enough to finally find a 38 knucklehead oil pump. It did however come with no springs. Mr Palmer lists 4 different by-pass springs, 713-36, 713-39, 713-41 and 713-42. The lengths are so close it's hard to figure if it would matter which spring you use, but. It may make a difference that I'm not aware of, You would think that Harley made positive changes, but it appears they made the spring in 42 shorter than 41 so what do I know. Any suggestion as what spring to use?
    Thanks
    Max

  2. #2

    Re: Knucklehead springs

    Quote Originally Posted by maxglass View Post
    Greetings
    I was fortunate enough to finally find a 38 knucklehead oil pump. It did however come with no springs. Mr Palmer lists 4 different by-pass springs, 713-36, 713-39, 713-41 and 713-42. The lengths are so close it's hard to figure if it would matter which spring you use, but. It may make a difference that I'm not aware of, You would think that Harley made positive changes, but it appears they made the spring in 42 shorter than 41 so what do I know. Any suggestion as what spring to use?
    Thanks
    Max
    I suggest you use the one made for your particular year pump. or you will be the next guy on here trying to figure out why your spraying oil out the front head.

  3. #3

    Re: Knucklehead springs

    Thanks
    That was my original thought, however I did a Google search and 713-36 didn't show up anywhere, even J Boone. The only part number I've even seen is the 713-41 part. My thought was, that the earlier part was either obsoleted, as the later spring was a better part or I just haven't looked hard enough. I also cant find the new part number for the -36 spring. Its possible that there is information listed in the shop dope books that I just haven't seen.
    Thanks
    Max

  4. #4

    Re: Knucklehead springs

    I also cant find the new part number for the -36 spring.
    713-41 superceded the early springs.
    Most 38's have upgraded to newer pinion shaft with separate gear which spins pump faster.

  5. #5

    Re: Knucklehead springs

    Thank you. I've ordered one.
    Max

  6. #6

    Re: Knucklehead springs

    It is likely the later spring won't work if you are running the stock 38 pump, what T bone said is correct , the later springs are stiffer which pushes more oil to the heads. I ran into this problem on my 38 and ended up cutting down a later spring , essentially trial and error.

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