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

Hello Tom!....I am glad a few folks are following along in my adventures with tiny hit and miss engines,....I Will continue to post both my Wins AND my losses....as we Can learn from when things get Worse as well.
     I have not removed the second o-ring yet as I have obligations today....but got the idea from a forum post of the full size engines...they where talking about slowing down full size hit and miss engines and retarding the timing often came up...but one guy said he likes to find an engine that is " loose" with well worn piston and bore and noticeable blow by of the rings...this is a lower drag engine and the ring blow by also has the effect of lowering the compression ratio of an all ready low C/R engine!.... The piston to bore fit (on china engine) is fairly close in my opinion for a hit and miss engine....I am hopeful that Just the film strength of MM oil will give me enough seal to run.....I suppose a thicker oil would greatly improve seal but that would not help with the low drag...I don't know if there is anything out there as thin as MM oil that has lower drag characteristic.
   Speaking of oils...I did read your thread about getting down to 38 hits with just fancy oils and a softer Gov. Spring....Gil posted an answer to one of my questions about which model china engine might be the best to tune for slow run and he suggested the M90 model you have....I have one new in box and think I want to get it out!....I saw a video last night of an M90 with head removed and it "looks" like the M90 has larger valves than my M94....I want to measure to confirm this but the combo of larger valves PLUS M90 has valves in the head so the air pathway is the best and shortest pathway possible.
   My M94 the exhaust has to travel up the threaded spark plug hole...then turn 90 deg and go down a long smaller hole then thru a brass side exhaust feature....I think the M90 is a better place to start for performance tuning....glad I just happen to have one in stock....lol
    As long as we are brain storming....I had another idea....one of the best upgrades you can do to a flame licker engine is make the entire ring-less piston from graphite!... This allows you a self lubricating Very low drag piston....key to making this work is a very well polished bore as the tipical cross hatch scratch pattern will slowly wear away the piston....if the bore Starts out polished and the piston starts out close fit...it Can be a long life piston......I do not know if Solid graphite piston has ever been tried on an internal combustion engine as the forces applyed to piston are much greater than any vacuum engine....however....our little hit and miss run so cool that o- rings live for a long time...and if we lower compression significantly...they run cooler still and with less strain.....I have access to some super hard premium graphite used in the tool and die trade....I want to Try it some day in the future......specialy IF my engine runs well with zero o-rings....thats all I have for now...got to go fill obligations.....