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Is my Cam/Crankshaft 1/2 tooth out of alignment, please help?

Discussion in 'The Garage' started by db650, May 15, 2018.

  1. Hello,
    First I read many of the existing threads, yet could not find a photo describing my problem, so here goes.
    I rebuilt my '75 447 motor with new pistons, cam chain DID 219 master link type, chain guide, Athena gaskets.
    The cam seemed 1/2 tooth misaligned with the crank no matter what I did. I read that tensioner may rotate the cam backwards once everything it torqued down. So, I favored the misalignment to be rocked forward. Now it's together, torqued, tightened, yet still misaligned.

    It is not quite at the 1:00 position as mentioned in other treads for being one tooth off, more like 12:30. Any ideas? Is this within some type of tolerance, or do I need to go in an pull the valve cover again and index the cam one tooth? Bad/wrong cam chain pitch?

    a) The attached photos show the pin hole on the rt side of the cam with the crank mark at TDC. (The TDC seems accurate using a wooden dowel) Also is shown the cam chain tensioner.
    b) Rotating the motor CCW turns fine. I tried CW (wrong way) with a wrench and seems to bind. I didn't force it, is this normal or is there an extra part fallen inside or something?
    c) I rotated the engine CCW about 12 times with a wrench and a little extra cam chain tension to see if things would seat.
    d) the cam and motor both are stamped 447

    Any sound advice is greatly appreciated. Thanks!
     

    Attached Files:

  2. Also, when the cam is aligned at 12:00, the crank is aligned directly on the 'F' mark.
     
  3. grizld1

    grizld1 Grumpy old man Top Contributor

    Either deck height has been lowered or your cam chain is shot. Scroll down to the thread by Chris k and read carefully; everything you need to know about your problem is there.
     
    robinc likes this.
  4. Thanks for the info, I somehow missed that thread. I'll tear it down again and check it out. It's a brand new cam chain, so that shouldn't be the issue, but I'll measure the pitch. Also, when I rotate the motor, the cam chain tensioner goes in/out slightly by about 0.5ish mm. Is this normal, or is something bent? Lastly, I'm wondering if the slightly thicker Athena head gasket could contribute to this?
     
  5. 5twins

    5twins XS650 Guru Top Contributor

    18,015
    7,992
    688
    I've used several of the Athena head gaskets on builds over the years and never had this alignment issue. Yes, it's normal for the pin on the cam chain adjuster to "pulse" in and out slightly. Chains, even when new, has slightly tighter and looser sections in them. It does appear you're one tooth off with the chain install. It can be tricky to get things lined up just right.

    All that being said, this is the 2nd time recently that issues seem to be cropping up with that D.I.D. chain. Maybe there's a bad batch out there now? I used a few of them many years back without issue but I pretty much use Tsubaki chains exclusively now. Was your new chain a tight fit?
     
  6. grizld1

    grizld1 Grumpy old man Top Contributor

    The center of the "F" marks is ~15* BTDC, so you're close to 1 tooth (20*) too far advanced.
     
  7. Thanks for the info. She's coming apart again to see what happened.
     

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