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Timing chain jumped a tooth...how to fix?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, May 20, 2001.

  1. 90K5

    90K5 1/2 ton status

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    This is on that '78 again. I fixed the distributo, and it sparks now. The problem NOW is I think the timing chain jumped a tooth, or teeth. Its getting gas and sparks, so I think this is the problem. The distributor is lined up excatly how I took it out. Could I fix the timing temporarliy by turning the distributor? Which way, and how much? I'm sure this thing needs a new timing chain, its got at least 200K on it (300K?) and he's had to get the timing set several times.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  2. Sparky87k5

    Sparky87k5 1/2 ton status

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    If the timing chain jumped a tooth, then the cam is no longer in time with the crankshaft. You may be able to adjust the distributor to be in time with the crankshaft but the valve timing will be off. Best to pull the timing cover off and replace the timing chain & gears with a new one. Use a good quality double roller chain and sprocket style. Although with that many miles on an engine, might be better to rebuild it too.

    87 K5, D60 & 14FF, 5 sp & NP208 & 383 stroker. Build it Bulletproof and take it fishing!
     
  3. 90K5

    90K5 1/2 ton status

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    So basically, there is not really a cheap way to do this? I already told the guy he needs to get out of this truck, it has major issues. It needs to be sold, but can't be sold unless its running, and he's gonna lose lots of money.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  4. Sparky87k5

    Sparky87k5 1/2 ton status

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    To put in a new timing chain isn't too expensive. Timing chain and gears cost about $40-50. Gaskets another $15 and about 3-4 hours labor. Not a big job.

    87 K5, D60 & 14FF, 5 sp & NP208 & 383 stroker. Build it Bulletproof and take it fishing!
     
  5. jimmyjack

    jimmyjack 1/2 ton status

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    I've seen double roller timing chains for as little as 20 bucks at places like Naps and Pepboys. Not really hard. Might as well replace the water pump while your there. Only 20 more dollars. Summer is here, here in Tucson anyway!

    "My blazer may be slow, but it goes faster at higher speeds"

    Jim
     
  6. CaptCrunch

    CaptCrunch 1/2 ton status

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    Again I will ask was it like this before???? The odds of the timing chain jumping at the same time all this is going on is like a thousoand or even a million to one. Are you sure the distributor didn't get spun while it was out? I bet a million to one this is your problem. Pull the distributor out and get the motor at tdc on #1 and line up the rotor to fire at the #1 cylinder... hopefully she'll fire up... set the timing w/ a timing light and you're done. Should be one happy truck now [​IMG] w/ shiney new coil, pickup and set timing.

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  7. 90K5

    90K5 1/2 ton status

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    What do you mean spun? If your talking about what I think you are it would make sense, becasue I thought it was kinda shady that the distributor would break and the timing chain would jump at the same time. Anyway, what is involved in getting it to TDC?

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  8. CaptCrunch

    CaptCrunch 1/2 ton status

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    You should just pull out the distributor and and pull the #1 plug... keep tapping the engine over till you feel compression or air popping out against your finger and you should be close to tdc... then line up the dist in the intake and make sure the rotor is lined up w/ where the #1 plug wire comes out of the dist cap. You might need to turn the oil pump shaft so the key lines up right in the oil pump shaft. put her in... get it going and then put the timing light on it. Good luck.

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  9. DMK

    DMK 1/2 ton status

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    I agree with captcrunch, chances that now the timing chain jumped a tooth are slim to none. Good advice capt.[​IMG]
     
  10. 90K5

    90K5 1/2 ton status

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    How do I tap the engine over?

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  11. klier

    klier Registered Member

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    Just have someone engage the starter in short bursts. Do this until you feel the air pressure against your finger, like CaptCrunch said.

    Brian Klier
    '86 K5 Blazer
    [​IMG]
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    If you wanna do it really quickly, crank the engine over until the timing mark on thebalancer is at 0 on the timing tag. that is either TDC, or 180 off. Put the dist in (rotor facing #1 cylinder)you will know if its 180 degrees off, it sounds funny as you crank it. (kind of a blub blub, like marine exhaust that exits at the waterline on a boat, VERY technical terms lol) If it isn't, it will turn over decently. From there, turn dist cap forward and backward to get timing close. Too advanced and it will be hard to turn over, you will hear the starter "fighting" the motor, as it will be trying to fire against the starter. Its easy enough now that the dist. has been out to just pull it out and put it back in 180 degrees from where the rotor just was. IE if the rotor was pointing at #1 when you pulled the cap, and you suspect you weren't at TDC, then pull dist out, and turn rotor 180 degrees, and reinstall. Thats 180 degrees after it drops down into the hole, not before you drop it in of course.

    Of course balancer could have slipped, etc., but for ease, I'd try it assuming the balancer is correct.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  13. DMK

    DMK 1/2 ton status

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    Use the key to bump it over, just turn on anf off quickly. Or you can use a breaker bar and socket.
     
  14. 90K5

    90K5 1/2 ton status

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    Thanks guys - I'm gonna work on it today.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     

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