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

My engine came with (2) o-rings on the piston....it seems the general consensus is one is better...I removed the one farther from the spark plug.
   It still has Plenty of compression even with the deeply dished piston....I did not really want to remove more from the piston, so I dished the Head!...I noticed the intake and exhaust are deep in the spark plug hole....I dished the head to lower the compression a bit more And try to get the path for the intake mix a bit shorter....to my surprise the dished head seems to have made Very little difference in performance!
   The photo is the head machined...with the grind on my ball nose cutter combined with the spark plug pilot hole caused quite a bit of tooling chatter. I can polish it out but it was kinda cool looking so I left it for now...lol