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Thread: Re surfacing cylinder head

  1. #1
    Join Date
    Mar 2018
    Location
    Ohio
    Posts
    88
    My Cars
    2001 BMW 325xi, e46, m54

    Re surfacing cylinder head

    2001 325xi.... Just had heads machined. Never really had a head machined before. I remember reading something online about not shaving too much off of the heads because it retards the timing on overhead cam engines or something along those lines. I honestly don't know how much is a normal amount to have machined off. They shaved off 0.015 (fifteen thousandths of an inch).... Not sure if that's less than normal or more than normal. I know they make a special head gasket that is thicker, but I wasn't sure if it would be necessary with 0.015 or not. Thanks.... And for the record, iv been searching online for this info but just not finding much as far as how much is too much.

  2. #2
    Join Date
    Feb 2018
    Location
    caribbean
    Posts
    72
    My Cars
    09 x3
    on paper that's correct. if you reduce the center to center distance on any chain driven or belt driven system you automatically change the relative timing of the two pulleys that they are driving. having said that .015 is not a big deal and it would depend on the diameter of the pulley or gear as far as the angular error that would occur. on a very serious racing engine you would degree the cams anyway so it wouldn't be an issue. on a street motor I can't imagine it will make any difference at all in any respect. if you think about how much a chain will stretch over time under normal circumstance it's easy to understand how much leeway there is on a street motor.

  3. #3
    Join Date
    Mar 2018
    Location
    Ohio
    Posts
    88
    My Cars
    2001 BMW 325xi, e46, m54
    Okay thanks for the info. I didn't figure it was a huge deal for this particular situation, but again I hadn't dealt with this before myself.

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