Adnoh, an educated guess is all I want or can ask for suggeted octane. don't worry about the timing, this Briggs
Engine has mechanical adjustable timing and the MSD timing box too. that's a whole other ball of wax to figure out later, just going to leave it as is for now. More info to follow soon, need anything else too, let me know.
stock stroke....68mm
big bore....87.00mm Wiesco
lightened crank
piston skirt length...76.25mm
piston window port(intake side)...1.50" X .25"
exhaust spigot...51mm ID
base spacer plate...5.60mm
sleeve thickness...2.79mm
head info....twin plug NKG B9ES
inner dome width...69.73mm
outer dome width...87.00mm
inner dome volume...30ml/cc
outer dome volume...12ml/cc
total volume...42cc
squish... .0525"-.054"
squish angles...????
piston angles...????
The compression test yielded about 137-140 lbs which suprised me. I was expecting much higher. I also expected a lower CC dome. I still need to figure ring end gap and piston wall clearance(no feeler gages with me). Fresh hone and new rings might help compression, or just need to run it a bit to get them re-seated????