1957 S4 Mk2 Valve timing

[BrianReynolds]

Another question for those experienced in rebuilding the Mk2 S4. I am at the stage of valve timing the engine, I have set up 2 dial indicators with the cylinder head off. I set no 1 piston 3/16” BTDC ( 0.0187”) then another dial on the No 1 Inlet valve cam follower. The closest I can get the timing after trying all 3 engine sprocket keyways is that the cam follower has lifted 0.003” when the piston is at 0.187” BTDC. This appears to be accurate according to Waller and Modern Motorcycle Mechanics. However, as you can see from the photo, the actual timing marks are way out. The 2 holes in the camshaft sprocket do not line up with the mark on the crankshaft sprocket I have read that the timing marks can be inaccurate . It is set that the inlet valve will start to open at 3/16” BTDC which I think is correct?

[klaus gerhard]

I remember that Bruce Longman modified the timing of his Mk2 engine by using a stepped woodruff key.

[nevhunter]

20 teeth with 3 keyway options get's it to 5 degree increments. I'd accept that in the retard direction (valves) as it will advance as the case heats up. Nev