Pasco 42cc twin two-stroke

Tom Pasco is a prolific builder of novel freelance I/C engines, each with one or more notable features. This one, photographed at Bristol and Doncaster, is one of the latest.

It is a 42cc two cylinder opposed piston two-stroke, supercharged engine with a sliding vane type compressor and geared up 2.56:1 to crankshaft speed. The exhaust crank leads the inlet by 15 degrees, which allows the inlet and exhaust port to close, more or less, together.

At the front end is a train of five gears supported on ball races. The propellor is geared down 0.7027:1.

Crankshaft, main and big end bearings are all plain, lubricated by a gear pump drawing oil from the sump through a paper filter.

Reported maximum speed so far is 3400rpm with a 24” x 10”propeller and crankshaft speed of 4838rpm.