Yep thats right racinrc14 i had a exhaust port timming of 140 degress which is actually higher than i had expected.
Thanks for all the offers i dont know what i need at the moment. I really need ideas on reducing the crankcase volume.
I think that may bee a good idea on the moving test 9 for 10.
I know I need the bowman ring. Like i said in an erlier post.
While tearing my engine down a inspecting I realized that I already had the zero gap rings with the notch to fit over the piston pin. My cylinder must be a little worn as i am getting a .019 gap on the top ring and a .017 gap on the bottom ring. I dont know if a new set would have a beter gap or if its my cylinder.
at this rate its no quite zero gap lol
While reading through this thread again reviewing all this info i found a post i had missed. I dont know how i missed this and he has a very good point.
nitro joe
"unfortunately like you say the older engine has the single ring piston which is pretty lousy. In my opinion so far the best set up is to find the older engine and then get the new style two ring piston to put in it."
To be fair to this lowly design:
(1) What did the end gap of this piston ring measure?
( 2) Was the ring face and sides free of any nicks,or scratches?
( 3) Condition of the bore it was asked to run in?
(4) Did you check the ring on a surface plate ? (Glass plate with a new piece of ~ 1000 grit oiled wet/dry)
(5) What was the piston ring groove to ring clearance?
(6) Is the piston groove completely contamination free?(no burs,nicks,or contamination)
Some folks call this "blue printing", measuring all the basic stuff, before messing with the mods.
Just an old mechanic wondering....
It would seem unfair to dismiss a design that has proven very effective in minimizing friction in countless high performance applications,due to missed concepts,with such a blanket statement.
It very well may be the best set up would be the single ring with a zero gap and it might have the benifit of less friction. I think this is worth testing but i really dont want to spend the money on a ring for this test. i guess it wouldnt be to bad at 12 bucks but my piston is pretty scored up and i dont think it will seal well on the ring lands. I do know my numbers may be somewhat skewed as my cylinder is used and not new or perfect by any means.
av8tor1977 what exhaust are you using on this engine? I am wondering if and when i go to electronic if mine will run right up there with yours. oh yea what prop also i think an acp prop gives very different results from a dynathrust but i just like the dynathrust look better lol.
Do you guys think maybee my 12.8 mm venturi carb is to big. I know most guys on here go with the 11.1 mm venturi carb and seems to be the standard.
What i am thinking for the reducing the crankcase volume is to switch the seal to where it is next to the ineer bearing rather than on the outside. this will reduce the volume in the crank shaft bearing housing. it wont let the outer bearing get lube but a sealed bearing with grease should be ok for that.
From there I am wondering just how much farther inward i can move the backplate. I think the only way to do this is to machine the back of the case and i would rather avoid this.
I am also thinking of machining my own backplate from a piece of plastic.
I have some other ideas but i need another backplate and an old junk case to experiment with.
It would be nice to be able to stuff the underside of the piston with something. unfortunatly i dont think this would let the piston cool properly.
Ajonr might you have another backplate and a junk case? mybee even a 11 mm venturi carb for comparison?