VALVE LIFT?

[Dave the Wave]

491 casting heads, .480 lift cam in now, how can i tell if they will handle .510 lift? thanx.

[Rick_L]

You need to measure the distance from the bottom of the valve spring retainer to the top of the valve guide, or the valve stem seal if you have them. Subtract the amount of lift from that measurement. Should be .060" or greater.

You also need to know whether the valve spring is going to coil bind at the new lift. Again, you should be more than .060" greater than the coil bind height.

Last, and this is not really part of your question, you may need to measure the valve to piston clearance.