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

Hi Tom, I honestly don't know enough to form an opinion of your special dimpled liner idea. However I do believe you know more than enough to make a fantastic running machine out of it and I encourage you to do this if you can find the time. Please bring us along for the ride if you go for it.

I know yours already runs and starts great so "fixing" it isn't a major priority and I understand this well. 

For the piston, I started out cutting the top off perfectly flat by about .100" to .105". On more recent engines I have taken up to .125" and carved a .075" depth bowl into a couple of them. I would like your opinion here.... Is there a point where taking too much of the top off would change the piston geometry enough to affect wear patterns. If so, I could reduce the amount taken off the top and make up for it by cutting a much deeper bowl into it. That said, My engines will run mostly all day for 2-3 days straight at shows.
Gil