{HEAD ~ The intake/exhaust valve member} is axially movable within the combustion chamber, and operatively cooperates with wall structure of {TAIL ~ the combustion chamber} 
{ HEAD ~ The intake / exhaust valve member } is axially movable within the combustion chamber , and operatively cooperates with wall structure of { TAIL ~ the combustion chamber }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL