[Steam Driver]

Spent another frustrating morning on timing the left cam for doing the valve clearance check. Didn’t get it done but I think I found an issue, at least for that side. I can’t explain how it got there but it is what it is.

The sprocket on that side fits the cam nose really tight. So tight, in fact, that I had difficulty getting it off when I decided to give up and disassemble things. That at least partially explains why there was so much difficulty adjusting timing as the sprocket wasn’t able to turn freely relative to the cam and change their relationship. Examining the sprocket bore I could feel two high spots on the back edge; tiny but definitely there. Now here’s the weird part. On the rear face adjacent to these high spots are two places where it looks like the sprocket has been struck by something, like a screwdriver blade possibly, that has offset the metal into the bore a little. If those had been on the front side I can see how someone might have tapped them onto the cam, but since they are on the back (at least in the last iteration of the engine) that side of the sprocket is inaccessible to hammer blows.

I’ve been thinking about the frustrations of this a lot. Maybe too much. However in doing so I have conjured up a scheme to assist cam timing that I think will work very well. Your opinion may differ; that's why I'm throwing this out for consideration.

So, here’s my idea.

Additional parts required (“tooling”):

M12 X 1.5 nut (Home Depot, etc.), M12 X 1.5 X 50 bolt that is threaded for the entire length OR
60mm bolt that has more threads than the existing camshaft bolt. It has 30mm worth of threads, we need more than that.

These bolts will involve going to a hardware place a little more specialized than Home Depot.

What you do with these items is run the nut up on the M12 bolt as far as you can, screw the bolt into the camshaft as far as you can, then run the M12 nut down and tighten securely against the cam nose. (This can be done with a pair of 19mm combination wrenches but if you wanted to get fancy you could get a cheap 19mm wrench, heat it with a torch, and bend it to fit the space better.) Now you have a tool you can use to either hold the cam still while you turn the crank (sprocket pin out of course) or just turn the cam itself. Once everything is indexed where you want it, undo the jam nut, remove the bolt, and replace it with the regular heavy washer and factory bolt.

My original thoughts on this were to just use the regular cam bolt with the nut run up on it. However it’s not long enough and thread engagement in the camshaft is insufficient.