An engine is like a safe deposit box with two locks. You can unlock one of these with such keys as carburetors, manifolds and ignition. But you can't open it up and get all the performance you want ...

1. Net valve lift is the amount of lift (imparted to a valve) as measured at the camshaft lobe. 2. Valve duration is the period of time during which a given valve is off its respective seat and ...