Quote:
Originally Posted by jhein
Seems like it would be pretty easy to measure the amount of torque required to turn the cam with the valvetrain fully assembled. Also seems like it's possible that it could be slightly different in a running engine with the the gasses flowing, compressing, combusting etc. whatever forces that may exert on the valves.
|
Quote:
Originally Posted by chuckies76ta
Case in point. Take the spark plugs out and spin the engine over. It spins pretty easily. So there can't be that much resistance to the valve springs.
|
Fwiw engines with stiff springs are noticeably harder to turn over by hand. The first engine I assembled that used 1100 pound springs (380 closed) seemed like it locked up after installing the first rocker arm. I was thinking the valve was hitting the piston. After the rest of the rocker arms were installed that engine turned over easier. So there is some merit with the theory the closing springs help the opening springs fight the spring pressures.
However I have yet to see one keep spinning on its own.
