RE: compression ratio
Easy, a good squish clearance is .019-.020 in. This will accomodate most nitro % from 20% on to the higher in the normal range for r/c cars. If you burn out plugs despite this, you are running too lean on the high end. Take the glow plug out and do this, take a length of solder and bend it to an L shape. the short part of the L should be about 3/8ths long. Place the short L into the glow plug hole and touch the end of the L against the liner. hold this as you turn the flywheel by hand so the piston passes top dead center. Take out the solder piece and measure the squished end. This will be your deck height and you can add or remove shims as required.