[Dark_5.0]

Originally Posted by Gearhead999

Dark_5.0, I think you should reread what you typed about piston to valve clearance having more to do with duration than lift.

Lift is the amount, distance, the valve opens.
Duration is the number of crankshaft degrees that the valve stays open.

The valves and the pistons need to clear one another at all times, with the engine in time. If the engine goes out of time, now that's a different story. As in jumped chain/belt, broke chain/belt or poor installation.

No matter how many times I re-read it I will still be correct.

When the intake valve is open the piston is on the down stroke. It is when the valve stays open too long (Duration) that you have problems.

This is coming from Ed Curtis who is a cam building God in the mustang world.