I built an Upsure Engine that was detailed in Strictly IC a few(!) years ago, but I think there may have been a mistake in the plans, as My piston only came to about .168" of the top of the cylinder. This meant that I had almost no compression. I could put my hand over the bore and the piston would not fall out, so sealing was not a problem. Anyone out there that can tell me from first hand experience, how close is the piston to the top of the bore? in your build.