Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Something seems off with your numbers.....My 2019 M-90 (same as ET-1) came thru with 8.0 mm crankshaft mains OD spinning on 8 mm ID/12 mm OD Needle Roller bearings...I later replaced the factory Needle bearings with same size Oilite type, sintered Bronze bushing....Unless your motor is built without Main bearings .....You might be able to easily "tweak" a similar bronze bushing to get the exact clearance needed without cap shims...