RE: Early Wen-Mac Identification
I have run Testors versions of these in my control-line building days, and they are simply just flat on power. It just seemed they were always choking for air...must be the exhaust slits not big enough I think. They just ran much quieter and at a lower rpm compared to a Cox. Almost like a really fast steam engine. Also if I remember right they had a larger diameter piston than a cox also, which means they must have had a shorter stroke to them for the same displacement.
I remember running one on the Cox racing fuel as an attempt to get the power up in it, and it cooked the piston in less than five laps. That was with a super rich needle too. I remember looking at the piston after getting it out and admiring the nice rainbow colors it had on it. After that happened I kinda passed on Testors engines when I would see them.