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  1. #1

    Default Compression tester recommendation for 1984 3.8?

    Hey all, Newbie here. My cheapo compression tester too fat for the plug holes on my 3.8. What brand compression testers work on a 3.8?

  2. #2
    FEP Super Member webestang's Avatar
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    Welcome!
    I bought one like this cause it has multiple ends. If your 84 3.8 is like my 99 3.8 it should be a 14mm thread size.

    https://www.amazon.com/Compression-C..._EALw_wcB&th=1

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  3. #3
    FEP Super Member gr79's Avatar
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    Yes the kit looks well equipped decent price.
    Hose type that screws hand tight directly into the spark plug holes.
    Has button below gauge to quickly release a reading and do another.

    Push on type is a two man job and not nearly as easy to use as a hose type.
    Do not have to hold the hose type gauge configuration when testing.

    I connect mine by starting the hose end in the hole then spinning the gauge with hose hand tight.
    5-10 cranks will get the highest readings. write down, repeat, move on to next cyl.
    Cold or warm engine readings can be a bit different, as can closed or open throttle plate position during tests

  4. #4

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    Thanks - that's exactly the set I bought. Issue is the 1984 plugs were really thin - see a pick of a autolight 2546 plug, Yes threads were 14mm but the threaded area is like over an inch long.
    Quote Originally Posted by webestang View Post
    Welcome!
    I bought one like this cause it has multiple ends. If your 84 3.8 is like my 99 3.8 it should be a 14mm thread size.

    https://www.amazon.com/Compression-C..._EALw_wcB&th=1

  5. #5
    FEP Power Member richpet's Avatar
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    The tester does not have to go far in at all. As long as it seals the compression is the same in the air chamber (above piston squish area) which now just includes a few more CC's of volume (potentially) if the tester does not go as far in as the plug. You can still get a good compression idea.

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