Quote:
Originally Posted by Jamesp
Well then you should be using 2 cam locks, not a cam lock. It would be interesting to understand what would you think could drive the cams to move independent of the chains as there is no driving force to rotate them at TDC to lose timing. I've had my 3 chain apart and set the timing without the cams locked, all that was needed was TDC as there is nothing to cause the cams to rotate independent of the chains. Tearing the engine down for the first time after an IMSB failure, I made the choice not to be at TDC because I thought I might have valve to piston interference if I rotated it. A poor choice as I can confirm through personal experience the valve springs will rotate the cam independent of the chain if not at TDC, and they will not, and indeed can not if the engine is at TDC. I prefer to complete jobs without unnecessary parts (cam plugs) and time (messing with the cam locking tool).
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As I have always been brought into the issue after it has already happened, I can only surmise what is causing it. That said, I would put my money on the removal of the tensioners, and perhaps the order in which that is done. Removing the tensioners has a similar effect as valve spring tension would, only to a lesser degree. When one tensioner is removed, the load on the chains is asymmetric due to the released tension. I have discussed this problem with other shop owners that have encountered it, and that seems to be the general consensus of what happens.
You also have to ask yourself why Jake even developed and LN produced three chain cam locks at all if they are not required during an IMS retrofit.