internal combustion (IC) engine (see crank and cam shaft animation)combustion cycle high-speed videocoordinated valve and piston motion at 4000 rpm and 2000 rpmvalve spring tests with engine speeds increasing from 1000 to 6000 rpmsame test with a few coils removed from weak spring, 3500 to 6000 rpmclose-up of weak spring at 1000 and 6000 rpm, showing valve float and spring surgeplot of cam profile
