electronic means suitable for causing the spark in the spark plug in each cylinder whose piston is located near a top dead centre as identified by {HEAD ~ a sensor} placed on {TAIL ~ a crank shaft} 
placed on
electronic means suitable for causing the spark in the spark plug in each cylinder whose piston is located near a top dead centre as identified by { HEAD ~ a sensor } placed on { TAIL ~ a crank shaft }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL