I am restoring a1939 m20.The project is nearing completion. On replacing the valve decom. cam valve lifter I seem to be missing a part/parts as there is no logical conection to the valve stem Am I missing something?

email (option): charles@woodbender.co.za

Hi Charles..The spindle that goes through the tappet chest wall should have an eccentric peg machined into it's end. This sits directly under the exhaust tappet head, which differs from the inlet one in that it has a flange running around its edge. The eccentric peg sits under this flange and when the spindle is rotated by lifting the valve lifter lever it lifts the exhaust tappet, which in turn lifts the exhaust valve...It is possible you may have two inlet tappet heads fitted and thus no flange....Ian

email (option): ian@wright52.plus.com

For something completely different: I have to grind a bit off of the peg.
Otherwise it did not fit under the tappet flange. My engine is also 1939.

John

email (option): john.kater@chello.nl

Adjustment can be fiddly. If you don't get it just right it will either (a) not lift the valve; or (b) not permit the valve to fully seat. The second alternative is obviously more problematic than the first, as it may result in the engine not starting or, if it starts, a burnt valve. You need to make sure that the two clearances, tappet-to-valve and lifter cam-to-tappet are just right.

email (option): jonny.rudge@verizon.net

John,

I would have shortened the valve stem. As a result of that the tappet will have to be raised and it will free up the peg from the valve lifter.

regards,
Leon

email (option): leonhop3@planet.nl

Thanks for the input Leon, or should I say output Could it be there is a
"strange" valve in the engine I know that I have flywheels produced after 1949.

John

email (option): john.kater@chello.nl

Hi John...Valves for all years of M20/21 after 1938 are identical. Possibilities are that you have a pattern valve fitted which may be dimensionally different or the exhaust valve seat has been cut a few times over the years, which will drop the valve further into the cylinder. Also the valve may have been refaced as well which would make matters worse.
When the valve is fitted the 'land' on the valve lip (above the valves seat face) should protrude above the gasket face (and be at least .040" wide). If the valve has be refaced too much or is badly 'pocketed' in the cylinder you should consider a new valve and seat the next time it is apart...This condition effectively reduces valve lift and performance, which an M20/21 hasn't got much of anyway.. ...Ian

email (option): ian@wright52.plus.com

Ian, thanks for the explanation Is there anything you do not know What I know is, since bought the bike in 1968 ( see: visitors bikes) there was no repair.
At the moment I concentrate on the concentric carb which should arrived shortly from Amal

(Some parts where not in stock

John

email (option): john.kater@chello.nl