{HEAD ~ Means} are provided for adjusting {TAIL ~ the relative timing} of the two pistons so as to vary the compression ratio of the engine 
{ HEAD ~ Means } are provided for adjusting { TAIL ~ the relative timing } of the two pistons so as to vary the compression ratio of the engine
HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH