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What should compression read?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K5thatShmobs, Oct 3, 2002.

  1. K5thatShmobs

    K5thatShmobs 1/2 ton status

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    What should the compression reading be on a simple compression tester for a 350 in an '86 K5?
     
  2. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I believe it is approx 150 psi. Put the compression tester in, crank the engine 3-4 revs and watch the dial. The max pressure is important, but how quickly it gets there is also important. If it jumps to 150 on the 1st or 2nd revolution you are good to go, if it takes the 3rd or 4th rev you are OK (still building good compressoin), but it means things are starting to wear. If it will not reach full compression, you have worn rings, valve seats, or bad head gasket (other things could be wrong but those are the most common).
     
  3. jimmyjack

    jimmyjack 1/2 ton status

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    It'll vary depending on the amount of milage you have. As long as they are all the same or close your doing pretty good.
     
  4. imiceman44

    imiceman44 1 ton status

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    Colorado K5 previous discussion
    Try reading a few posts before asking, We had this discussion yesterday night. You can just get more input if you concentrate the effort. /forums/images/graemlins/smile.gif
    IceMan
     

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