Valve to piston clearance?

Marcohotrod said
I think we need to add in how far the valve is recessed in the head from the deck surface of the head. calculating .075-.085 is assuming all the valves backs are even with the surface of the head-are they?
Click to expand...
Actually, I worked all that in.
  1. I started with how far the lowest edge of the intake valve sets above the head surface when closed; measured that on a 675 head to get a starting number.
  2. Then used .075" valve lift since the lobe lift at .050" occurs within a couple of degrees of TDC. Then reduced that .075" by the cosine of the valve angle.
  3. Subtract 2 from 1 to get the approximate intake valve-to-head- surface distance at TDC.
  4. Then work in how far below the head surface the piston top is.
If the .050" lobe lift number was not conveniently right at TDC, then this gets hard/impossible to work out on paper without knowing the exact cam lift vs crank angles.