Nelson,

the disc valve should be attached with a screw that is a backwards thread. Meaning looking down on the top of the screw it tightens by turning it CCW rather than CW.

A Screw that tightens up CW is a right hand thread. This is what all the threads are on nearly everything. The problem is on the disc valve if it was a right hand thread it would loosen up as the engine runs. SO they make it a special left hand (CCW) thread so that the engine running keeps trying to tighten the screw rather than loosen it up.

It has been a really long time since I had one of those 120SF motors much less worked on one. If I had it in front of me I could tell you what was up with it....but its tough to describe from 10+old knowledge. The last time I had one of those motors was around 1994 and it was old then. We were running 120AC's which I still have a couple of those.


Troy