theres three variations or more on the Como 51 .
this is the case for the Baffled / Ring version , near identical to the same ' 40 ' .
Another picture showing the concave ' plug - in ' head .
Theres a a.B.C. Version of this case , stamped ABC I believe , on the side of the mounting lug . Dunno if baffled , presume Flat Top Piston ? .
Then thers this sucker , ABC Schneurle , Flat Head - bit like a later ' X ; series Super Tigre . Piston level with top of liner at T.d.C.
though theres likely a Ringed version of this . was a Test of a ' Stunt ' ( control line ) version in the pommy Aeromodellor magazine .
B.H.P. readings at 2 & 4 stroke , shortish parralle; sided intake , spraybar through / center .
The ringed baffled ones came with a leaflet with the parts numbers on it . I have a few 51s & 40s .
Good to use for a twin m as the combined displacement is actually UNDER 15 cc / 90 Cu. In. This could lead to a few interesting arguments .