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  1. #11


    Back fires out the intake?
    Check to make sure your not 180 out on the timing.
    Easy to do even if you followed the manual closely.

  2. #12


    Backfires through intake. that made me reread previous posts, oops i missed it. you said you put crank & cam sprockets @ 12 o'clock, is that correct? crank & cam gears should have a dot on them. dot on crank points to 12 dot on cam points to 6 0'clock. dots together : if not, valve timing will be off. incorrect valve timing/ bent valve can cause backfire. on a lighter note, so can plug wires not in correct firing order. recheck everything you did.

  3. #13


    Compression test
    1 - 100
    2 - 120
    3 - 105
    4 - 110
    5 - 100
    6 - 110
    7 - 105
    8 - 115

  4. #14


    is your timing chain correct, as i said in my last post? low compression across the board indicates incorrect valve timing, ( timing marks on cam and crank not aligned correctly) or valve damage. since all cyls are low i suspect you did not get timing marks correct when installing chain. it is unusual to bend a valve on every cyl.

  5. #15


    The timing is correct. The books show TDC at 12 o'clock and the exhaust at 6 o'clock which I where I lined every thing at.

  6. #16


    I've never heard it described that way, but if by tdc you mean the crank and by exhaust you mean the cam then it's correct. if there is no chance you missed it by a tooth or two and your sure the cam & crank gears are not spinning out of position (off their keyways") you have valve train damage.

  7. #17


    With #1 at TDC the crank and cam marks are at 12 o'clock. On the exhaust stroke with the crank at 12 o'clock the cam is at 6 o'clock. As far as I can tell everytihng is in position.

  8. #18


    I don't know what manual you are reading but if you google chevy timing marks i'm sure you could find a picture. if i am under standing you correctly you are 180 degrees out. that would explain low compression and backfire. spark is firing when a valve is open. dots on crank & cam should line up. crank at 12 cam at 6. at this point #1 should be on COMPRESSION. " both valves closed" rotor pointing almost directly to #1 coil tower. #1 plug wire may not be in the same position as the tower so look closely at the cap. just curious, do you have timing chain exposed and valve covers off ?

  9. #19


    just curious, was this issue ever resolved?

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