Posted by HAROLD POLLNER on April 05, 2002 at 16:23:33:
In Reply to: Rocker arms-- Hal, your opinion? posted by Jim on April 05, 2002 at 14:52:20:
Jim...it's not just my opinion, but a FACT! What you say about the valves is absolutely correct. During most of the compression and power strokes, the valves are held closed by their springs, tightly sealing the combustion chamber, and leaving a small amount of play (valve lash) between the valve stems and their rocker arms. I say "most of" the compression and power strokes because there are a few degrees of cam overlap, allowing the intake mixture to continue entering the cylinder even after the piston begins to rise on compression, and opening the exhaust valve slightly before the piston reaches the bottom on the power stroke. This is known as "Cam Overlap", in is an important factor in defining the power band of an engine. Have a nice day!
"Stroker" Halbert
p.s. I'm known as Hal, Harold, Harry, Halbert, Halsworth, and many other variations...it's fun!