Timing won't stay set

Discussion in 'Classic Mustang Specific Tech' started by TD68302, Nov 14, 2008.


  1. hotcobra03

    hotcobra03 Active Member

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    How many vacuum parts on engine than change by eng temp ?vac leak will raise rpms?
    #21
  2. bnickel

    bnickel Founding Member

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    of the ditributor is not moving and the breaker plate and advance mechanisms are working correctly and the distributor shft is not loose in the housing (bad bushings in the dizzy cause this) the the only other possibility is a bad timing chain. if the timing chain is loose or the gear teeth are worn then the chain will slip and physically change the timing because it will either advance or retard the camshaft and the distributor as well.

    i would be willing to bet a lot of money you have a bad timing chain :nice:
    #22
  3. hotcobra03

    hotcobra03 Active Member

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    I forgot to read every word too.those things were said.i dont know who did motor and how long has he had this problem and are parts new or used ?
    #23
  4. hotcobra03

    hotcobra03 Active Member

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    What is a bad timing chain other than the chain itself?if gear is bolted to cam and its loose can we say bad timing chain?
    #24
  5. bnickel

    bnickel Founding Member

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    well technically a chain could be fine but a bad timing gear could cause the chain to jump. this is actually pretty common with 60's and 70's fords that used the crappy nylon cam gear....
    #25
  6. spirockp

    spirockp Member

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    Have you taken out the Distributor to inspect it? (I didn't see if you did.) I had this issue and after I pulled out the distributor I could NOT turn it by hand. Yes I know you state that the distributor is not moving, but I also don't think it's the timing chain, because if the chain was moving that much each time, your motor would never run.
    #26
  7. Capt Dan

    Capt Dan New Member

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    Does it run better when you move the timing back or is it getting worse?

    Could be your harmonic balancer shifting.
    #27
  8. spirockp

    spirockp Member

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    Good idea, I have seen that too!
    #28
  9. bnickel

    bnickel Founding Member

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    the balancer slipping won't cause the timing to change though, it will only change the position of the numbers on the balancer, which will be a problem when you try to set the timing but it won't change how the engine runs. i'm guessing this is why he asked the question in the first place. if the timing chain is stretched or is slipping a tooth the actual timing will be effected but the marks on the balancer won't move in relation to the crankshaft so the actual crank timing will stay the same, the cam timing will change though, however. if it only slips one or two teeth you can change the timing on the dizzy to help offset the effect but ulimately the cam timing will still be off.
    #29
  10. 10secgoal

    10secgoal Active Member

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    when you come back from the drive, is the car idling higher than it was. If the timing it really advanced, that will make it idle higher. I'd check to see if your dist gear is ok. If it's geting chewed up, it would retard it...but maybe a sheared pin. Only other time I've seen what your describing was caused by a broken block. Don't ask me how.
    #30
  11. TD68302

    TD68302 New Member

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  12. TD68302

    TD68302 New Member

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  13. TD68302

    TD68302 New Member

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    The idle is higher, I have not checked the pin or the gear yet. That is the only thing that I have not looked at. But after checking those things I'm out of idea's and it's another thing I will put in my book of wierd stuff, that I cant figure out about the car.
    #33
  14. zookeeper

    zookeeper Founding Member

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    If you are reading 42 degrees of initial advance, and it seems to be running good, then either your timing light is incorrect or your balancer is waaaay off. Something is definitely wrong.
    #34
  15. spirockp

    spirockp Member

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    Plus 1.
    #35
  16. from6to8

    from6to8 There's suction so I used that end O_O

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    Did you ever find out what it was? My car seems to be doing the exact same thing but the idle isn't changing once i get back from a drive. Only saw it changed once since i set it a few wks ago. Last nite i noticed it had changed. Drove car and it felt good. Started this morning and it went back to missing but I havent checked timing again yet because i drove it to work
    #36
  17. horse sence

    horse sence Please don't call me Mom SN Certified Technician

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    The easiest way to check a stretched timing chain is to take off all the belts ,Grab the lower pulley and turn it back and forth. You will feel the loose chain by how far the crank rocks back and forth freely .Timing chains stretch especially if the motor is driven hard .You will feel some slack ,but you will know it if it is real loose .
    #37

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