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two questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Langosta39, Feb 18, 2003.

  1. Langosta39

    Langosta39 1/2 ton status

    Nov 8, 2002
    Likes Received:
    Moscow, Idaho
    Ok guys, I used to run 2.5" backspacing, but now I'm running 4.5" (or whatever stock chevy is) and my 14.5" tires are hitting my pitman arm when turning right. Can I adjust my steering stops to fix this? Anyone else run 14.5s on stock BS wheels?

    Second, I am dreaming of a cam change, the milder CompCams 4x4 or the Crame dual pattern truck cam, but is it a good idea to do a cam change without changing cam bearings? Any considerations to take into consideration? : )

    thanks all,
  2. milspecjimmy

    milspecjimmy 1/2 ton status

    Aug 28, 2002
    Likes Received:
    raymond, maine
    how many miles are on it? i wouldnt think twice about tossing a cam in, i do it all the time. if it were a complete rebuild it would be stupid not to change em, but as long as the cam comming out looks ok, then go ahead. if you pull it out and it is scored all to hell on the bearing journals, the you need to change em any way. that and cam bearings arent a high failure item any way.
  3. Poohbair

    Poohbair 1/2 ton status

    Jan 30, 2003
    Likes Received:
    Ellensburg, WA
    I am running 38x15.50's on a stock 16.5x9.75 steel wheel w/ 4" lift. They rub the steering arm. No big deal, I just let it rub.
  4. the professor

    the professor 1/2 ton status

    Feb 6, 2003
    Likes Received:
    Ahhhh, I would worry more about the rod & main bearings...
    Even pretty severe cam bearing wear is not a problem, it'll just rattle a bit at around 3000rpm...In any case, you can see the bearings when you pull the cam, and look for wear
    Does it "rattle" pretty good when you start it cold..and the oil had drained off the bearings..?? Chevys shouldn't

    Oil pressure droping below 30psi at idle hot..??

    The rods and mains are tri-metal...usualy a steel backing, with copper plating and a lite coating of tin or alum..Clevite CL77's for example...

    GM stock bearings are usualy Moraine 500 or something similar..the major difference is they don't use copper, but I think its aluminum, with a tin over plate...

    What happens first, it the thin top-coat wears off,..the actual bearing material.... and you start to run on the bearing "cushion"..this material is harder, but usualy won't damage you crank..but doesn't wear that long...

    Lo-oil pressure at idle and a loose rattle sound at 2-3000 rpm are good signs of wear, as are a leaking rear main seal

    The next step is the steel backing and a spun bearing and a damaged crank, rods and even the block

    Keep the rpm down and they will run for a very long time "on the copper", rev it much and its history...

    The cam bearings are constructed in a similar manner, but wear much slower...unless you start putting 350+lb valve springs on it, a little wear there will last quit awhile...

    I just did this on my 454 (rods and mains), and the cam bearings were fine...

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