I have an M20 with the engine No SA86 with 22 HW also stamped into it . Can anyone give me some information regarding this? The engine is in a plunger frame and was I believe originally registered in 1952 , though it now has a 1963 (A) registration ?
No-one has come up with a knowledgeable answer. I'd suggest that the owners post some high-res images of the complete engines taken from several angles. There were casting differences over the years and it may help to narrow things down, as would other stamped markings.
