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

Hi all,  Got around to checking my M90 Exhaust valve timing. It's Opening at 46 deg BBDC & Closing at 38 deg BTDC at the valve (seems advanced). Is this (especially Closing point) off enough to noticably affect running performance ?  I thought exhaust closing should be around 5 deg ATDC & does it warrant correcting
as i only have this one.
 ...thx for any info, ..tom

Try a valve lash of .031". That will help some. The engine will run good with the exhaust beginning to open 10-20 degrees before BDC and closing at or very slightly before TDC and firing at TDC. (fuel: Coleman or other pure fuel or white gas mixed 15:1 with Marvel Mystery Oil)
Best of luck and have fun!


Gil