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Thread: Square tooth timing belt wont ride center.

  1. #1
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    Question Square tooth timing belt wont ride center.

    I did the timing belt on my 87 shadow. The belt always rode on the outer edge (passenger) of the pullys before belt change. It doesnt ride off of the gear but about 1/16 from the edge. Intermediate shaft has no slop and tensioner is new. Ive tried adjusting tension with the engine running and it always just wants to ride on the edge. Any ideas?

  2. #2
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: Square tooth timing belt wont ride center.

    That's typical, I've never had one that stays pefectly centered. If you want to be through, you can check the gear teeth with a straight edge to see if there is any wear. If you need a replacement gear, they are pretty common. The crank gear for my 1988 CSX-T was so worn, I could see it without the straight edge.

  3. #3
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    Re: Square tooth timing belt wont ride center.

    I was kinda thinking it might be normal. I dont have too much exposure to square tooth drives. I'll check the teeth for wear later and if theyre worn I have a round tooth setup and an some offset cam keys waiting to be used.

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    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Square tooth timing belt wont ride center.

    Round tooth will change change the cam timing, unless you use a roller cam. But I guess that's what the cam keys are for...
    Rob M.
    '89 Turbo GTC
    2.5 TIII swap is here!

    Project LookOwt
    '91 Daytona ES, 61k original miles, Rick Lozier's old 3.0 nitrous car
    Back to basics, then the mods go back on....

  5. #5
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    Re: Square tooth timing belt wont ride center.

    Quote Originally Posted by cheezit53 View Post
    I did the timing belt on my 87 shadow. The belt always rode on the outer edge (passenger) of the pullys before belt change. It doesnt ride off of the gear but about 1/16 from the edge. Intermediate shaft has no slop and tensioner is new. Ive tried adjusting tension with the engine running and it always just wants to ride on the edge. Any ideas?
    I always do the tension adjustment with the engine running too

    I've always felt I had it right when the tensioner JUST STARTS to make it's er,er,er cricket like noise .. JUST

    if it's more than just starting to make that sound it's to tight - the tensioner sound should not be the dominant sound coming from the engine

  6. #6
    Supporting Member Turbo Mopar Contributor
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    Re: Square tooth timing belt wont ride center.

    Quote Originally Posted by cheezit53 View Post
    I was kinda thinking it might be normal. I dont have too much exposure to square tooth drives. I'll check the teeth for wear later and if they're worn I have a round tooth setup and an some offset cam keys waiting to be used.
    Just be careful as the Turbo Cam gear (557 round) is different than the EFI (690 round).
    My CSX( 2.5 TII) vacuum was poor (10 inHg) etc. While changing to PT Lifters the other week, I noticed a PO changed the Cam gear to the 690. I changed to the normal 557 and the car worked much better including 16 inHg vacuum. My 88 Daytona Shelby Z used a square tooth (974) on a 850 roller cam.
    Some folks like the EFI and early 88 Turbo roller cam better than the later 721 cam used in Turbos after march 88
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    Project '87 CSX #432
    Donor car '88 Daytona Shelby Z, TII with S60 Turbo/smec, 3 bar.

  7. #7
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    Re: Square tooth timing belt wont ride center.

    Quote Originally Posted by chromguy View Post
    Just be careful as the Turbo Cam gear (557 round) is different than the EFI (690 round).
    My CSX( 2.5 TII) vacuum was poor (10 inHg) etc. While changing to PT Lifters the other week, I noticed a PO changed the Cam gear to the 690. I changed to the normal 557 and the car worked much better including 16 inHg vacuum. My 88 Daytona Shelby Z used a square tooth (974) on a 850 roller cam.
    Some folks like the EFI and early 88 Turbo roller cam better than the later 721 cam used in Turbos after march 88
    Isnt the 690 gear off of a 2.5 tall deck engine?

  8. #8
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Square tooth timing belt wont ride center.

    I alway just do a static adjustment, tighten it so you can just turn the belt 90 degrees on the tensioner/cam stretch, lock it down and rotate once and recheck. Never had an issue yet.
    Rob M.
    '89 Turbo GTC
    2.5 TIII swap is here!

    Project LookOwt
    '91 Daytona ES, 61k original miles, Rick Lozier's old 3.0 nitrous car
    Back to basics, then the mods go back on....

  9. #9
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    Re: Square tooth timing belt wont ride center.

    I'd be willing to bet you may have put a CB tensioner on an early block. Lots of catalogs have them listed as the same tensioner, but they're without a doubt, a different depth. A common block tensioner would move the timing block outward toward the passenger side. I'm trying to post a picture of the two, but now the site won't let me attach pics. Also can't reply with quotes either.

  10. #10
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    Re: Square tooth timing belt wont ride center.

    If interested in viewing the picture, here is the link. post #19.
    http://www.turbo-mopar.com/forums/sh...belt+tensioner

  11. #11
    Supporting Member Turbo Mopar Contributor
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    Re: Square tooth timing belt wont ride center.

    Quote Originally Posted by cheezit53 View Post
    Isnt the 690 gear off of a 2.5 tall deck engine?
    a 690 is 2.5 NA 89+ and I have a number of these I removed from later 2.5 TBI

    Here is the table from Gary D the Dodge Garage
    .
    There are 6 cam sprockets for the SOHC 2.2/2.5 family 1984-1988 "4201974" Square tooth 2.2 Turbo, 2.2 N/A
    1984-1987 "4201992" Square tooth hi-output 2.2 N/A
    1989-1992 "4387557" Round tooth 2.2/2.5 Turbo, 2.2 N/A
    1989-1993 "4448690" Round tooth 2.5 N/A "common block"

    1986-1987 "4273238" Square tooth, "tall deck" 2.5 TBI ONLY
    1988 ......... "4387535" Round tooth, "tall deck" 2.5 TBI ONLY

    and here are the microfiche if you wish to have look. For sure I did.
    http://www.glmwpg.com/ServiceManuals/
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    Project '87 CSX #432
    Donor car '88 Daytona Shelby Z, TII with S60 Turbo/smec, 3 bar.

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