NAMBA March 2021 Web

PROPWASH 22 March 2021 The required tapers on Jim’s pistons and liner were covered in part 2. Jim placed the wrist pin high in the piston. This stabilized the piston and allowed a long rod. Jim tried a lot of designs before this final version. Piston on Collet for Finishing Liner Machining Fixture with Locating Pins Various Allen 90 Liners Tested Allen 90 Pistons MB 40 Cylinder Design Rob took a different approach in his MB 40 engine. The cylinder is a one-piece investment casting. Its aluminum bore is chrome plated. The piston is machined from a very high silicon aluminum bar. It is so hard to machine that the inside is electrochemically shaped. The cylinder’s large diameter connection to the crankcase helps maintain the cylinder to crankshaft alignment at very high rpm. Note the thin wear band on the piston and the cylinder bore taper. These tapers are similar to Jim’s piston and liner. MB 40 Cylinder