349 CI on the cheap

Mal,
As you quoted above, I'll explain what happends. If the piston is .041 above the deck with the gasket in place, and the chamber is .095 deep, you have to take .095 - .041 = .054 at TDC + .200 for the valve relief in the piston, and you end up with .254 at TDC. Now the valves are closed at this point and as the valve starts to open, the piston starts to move down. Sometimes the valve opens sooner than the piston starts to move and this is why the pockets have to be so deep in the pistons. To take up the additional movement of the valve and to keep from hitting the pistons.

The valve doesn't get to full lift until BDC or just before. At this point the piston is 3" away from the valves. As the valves open the piston moves away and the valve vritually chases the pistons down the bore. The oppisite happends with the exh. valve. It opens just before BDC and the piston chases the valve closed so the pressure that the piston makes comming up the cylinder bore pushes the spent gasses out the exh. port and into the hedders. But usually the exh. valve doesn't need to be as deep as the intake valve pocket as the valve is further up in the chamber and further from the deck surface. But this is all dependant in the centerlines and duration at .050, which would open or close the valves eariler or later depending on how the cam is ground.

This is where the machinist really needs to know his stuff to make a high compression engine work with tight clearences. Hopefully you understand it now.