Perkins 4.108 valve adjustment

[roberttigar]

I am trying to adjust the valves and need a bit of information.

The workshop manual says-"Turn the engine so that the valves on #1 cyl are in the position of overlap. Adjust the cleararances of #4 cylinder. similary do the same with #3 to adjust #2" and so on.

I know that the British write a bit strange, but this doesnt make sense. What I remember from my younger days is that you should find the middle of the "overlap" and set the valves at that position-on that cylinder.

Someone must have the answer.
Bob

[DougR]

The manual is correct...Pistons #1 and# 4 travel up and down together, but when one of them is on overlap ( the end of the exhaust stroke and the beginning of the inlet stroke) the other piston is on compression. You can't adjust the clearances when a cylinder is on overlap because both of the valves are being held open slightly and there will be no clearance at all. When one piston is on overlap, the other will be on compression stroke and the compression stroke valves are positioned on the base circle of the cam and can be adjusted.

Same goes for cylinders #2 & #3.

DougR