This is an unproven experiment -- do not do this trick until it is proven out.
This post is written at EXPERT LEVEL discussing a potential new rework method -- it is a thought provoker, not a rework method (yet). proving out a trick like this takes years and years of running time, so be patientOK, we currently do this:
and in result we get some retarded cam timing by 7-10 degrees or there abouts by the time we wear it out. This isn't a big issue to us right now but it is there and we know it .... and there isn't anything we can do about it anyway.
The raised right side shows where the cam is rotated "backwards" by all the cam chain slack being taken up on the left side by the extended cam chain adjuster -- this rotation only gets worse as the second life of the extended cam chain tensioner system rolls on through.
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But ..... what if ???
What if we took out the chain wear on the front (right) side by bowing the stationary cam chain guide outwards?
Photos that follow show a trial mock up of such a system which is done simply to show the concept has a functional pathway to follow and has some results that might be worth pursuing.
I had a motor with a well worn set of guides and a half done chain and some extra fiddle time to play with it. The main challenge in moving the stationary guide forward was that the aluminum housings all have casting draft and the back of the plastic coated steel chain guide isn't flat (it is concave with blockish squarish injection molding features on it). Spacing it out
wouldn't be square if you put something square behind it.
Round rod (dowel) stock has good features for the use though -- the half inch round stock shown fits nicely in the groove in the back of the stationary guide, bridging over the squarish injection molding features and forcing the stationary guide into a bow shape with the rod/dowel acting as the string so to speak. A bevel on the inserted end of the rod is needed to "ride over" or "bump past" the injection molded squarish features when you stuff the rod in place by lightly tapping it home.
The round rod self centers on the chain guide groove and since it only contacts the off kilter aluminum housing in a single contact line it is not tilted or influenced overmuch by the casting draft in the housing.
A potential tight spot is created where the chain loads on to the small sprocket -- I think this will rapidly wear into the plastic surface of the chain guide though to the point the stress is relieved. Mind you, these are the original chain guides, so they will need replacement anyway when a new chain goes into place after this second life of the cam chain is used up.
Tensioner has almost all of its travel restored -- 22mm worth or there abouts. You only have 19.3mm of distance until the chain hits itself, so the announcement of "time to tear it down again" should be a nice loud whirring contact noise of chain to chain.
Now -- why might this be worth pursuing?
You get cam being advanced a tad at the start of the wear in, instead of being retarded. It will wear in to "normal" and likely not get any further retarded at the end of life than the system does now by the first tensioner protrusion life (first life).
And we won't say anything about the fix being easy or cheap or that somebody could sell a kit with a tube of epoxy and a piece of aluminum bar stock with some nice neat instructions.
We will reserve all of that until the idea proves itself out (or it fails miserably, who knows?)
And that will be years from now as this is my backup engine and my primary engine is doing jest fine right now ....
But, it is a thought to consider -- what do you see that is wrong with it (other than the use of wood of course). It does achieve tensioner reset without requiring a weld up job, it allows the use of used worn guides and it gets your cam timing run all the way back to zero (or slightly advanced) instead of retarding the nuts out of it ....
What'cha think?
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