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  1. #1

    Adjust cam/timing 05 Rxp

    I had a local motoplex put my 08 head on with supertech valves/springs/retainers and remove the oil jet in the block.

    Only ran 7300 rpm and 64 mph. Ran a compression test when I got back home and all 3 cylinders read 150+ psi. Before the head swap, it was running 8100 @ 72mph.

    Brought it back to the motoplex, they tore it down again and said timing was spot on. They didnt take a compression test before tear down either time, cuz they are retarded, but after they had it together the 2nd time they did. Claimed it was 140 psi on all 3 cylinders.

    They said my brand new compression tester must be wrong.

    From research from you guys and by talking to snoman, it looks as if the timing is off a tooth.

    I will take it back out tonight to verify speed and do another compression test.

    Can I adjust timing without taking the chain off and rotating the cam gear?

    I'm not very experienced with motor tear down, as you can probably tell, but it looks like I'm going to have to tackle this myself.

    Any pointers would be appreciated.


  2. #2

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    seems like those compression numbers are spot on. You dont need to take the head off to change the timing but i would be making sure your supercharger is working correctly first. 125-150 is where it belongs for the supercharged engine. Yes you can change the timing by unbolting the cam gear and rotating the camshaft but I would inspect the marks first.

  3. #3
    Supercharger has maybe 20 hours after a rebuild from Jerry, so I assume that's working good.

    Everything was perfect before the new head was put on. I will test compression again tonight.

    My compression a few years ago was 120 ish to 130 ish I believe. Now it's up to 140 after the head install and down 800 rpm?

    Excuse my lack of knowledge on this subject.

    Can I adjust the cam by locking it down and not playing with the timing chain?

  4. #4
    So I tested compreasion after they tore it down again, 130,130,140.

    They said they didn't adjust timing. Why is compression 10-15 psi lower all of a sudden? Lol

    I used same compression tester both times on cold motor.

    Won't be able to take it out til next week unfortunately.

    What gives?

  5. #5

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    Quote Originally Posted by fastrxp215 View Post
    So I tested compreasion after they tore it down again, 130,130,140.

    They said they didn't adjust timing. Why is compression 10-15 psi lower all of a sudden? Lol

    I used same compression tester both times on cold motor.

    Won't be able to take it out til next week unfortunately.

    What gives?
    Have you checked for boost leaks or maybe an intercooler leak? Your compression numbers are not concerning, I think you may be looking in the wrong direction. Are you running the 08 rocker shaft in that head? Which camshaft are you running? Your rxt cam is more desirable then the 08 cam.

  6. #6
    maybe you should learn how to fix it yourself

  7. #7
    Quote Originally Posted by 4tec Hoarder View Post
    maybe you should learn how to fix it yourself
    Great idea.

  8. #8
    Moderator Snoman's Avatar
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    Glad it is fixed now....Obviously they messed up and fixed it right,the second time....

  9. #9
    Quote Originally Posted by Snoman View Post
    Glad it is fixed now....Obviously they messed up and fixed it right,the second time....
    Thanks for the help brotha!

    It was definitely off a tooth.

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