One of the engine components that I did not look closely at in the original work was the cam chain tensioner. It is typically a device that once it is set, you never touch it again. Unfortunately, since the rear cam chain guide snapped at the interface location with the tensioner it appears that something was not set properly or became stuck. It is a very simple device so I went ahead and replaced the plunger and springs to make sure that everything was up to date after 37 years.
Nothing was obviously wrong with the original plunger and spring on the left, just a bit of wear on the plunger.
Once the new plunger and spring were installed, the plunger was compressed and the lock nut tightened to hold it in place before reinstalling it to the engine.
Once the tensioner is installed in the engine block, the plunger is released by backing off the set screw one half turn. The change in the main spring can be seen when the plunger is released on the right.
The cam chain tensioner operation can be confirmed by rotating the engine in reverse to create slack in the chain. The main spring will rotate to show that the plunger is moving to take up the slack. The engine should never be rotated in reverse again after this check.
With the tensioner working properly I could then confirm the valve clearances that I previously set. I was expecting the number 3 intake valve to have a different clearance with the valve replacement. The specification for valve clearance is 0.03 to 0.08mm and tends to get tighter as the engine is run and the valves wear. My original settings were at the higher end of the range and even a bit outside in the 0.10mm range.
Interestingly, everything was expected except for the number 1 exhaust valve. The number 4 intake valve went from 0.10mm to 0.12mm which I am ok with, but the number 1 exhaust valve was previously set to 0.12mm and was now reading 0.05mm. Still within spec, but not consistent with how the other valve clearances are set. In the previous adjustment I had changed this shim from 2.70 to 2.60 because it was under spec, 0.02mm clear. I decide to change again to a 2.55mm shim. The clearance with this shim is now 0.09mm which is in line with the other valves.
Now I have to figure out the best way to clean the remaining engine covers so that I can get this engine completed for spring time.