LDB wrote:Thanks for your reply, wz507. So if all cylinder heads were not cast parallel to the gasket surface then that means the round quench area recess above the piston must be at an angle?
Only the combustion chamber area immediately above the valves is angled at the same complimentary angle as the valves. The quench area over the piston is flat as a pancake and parallel with the gasket surface.
LDB wrote:I can see how there might be some benefit if the recess above the valves were tilted toward the cylinder bore, but both valves tilted one way to the side makes no sense to me unless the valve is at such an angle that it would hit the head if a matching slant was not maintained in the head. That would have to be quite a slant of the valves.
As I noted previously, the angle of the intake valve is such that for the 1.800" dia IN valve the difference in height, relative to the gasket surface, across the valve face (measured at points A and B on the valve head) is ~ 0.100" (trigs out to an angle of ~ 3.2deg), so yes there is a very substantial difference from side to side and yes a flat chamber in this area would result in 0.100" clearance above the valve on one side of the valve head and 0 clearance on the other side. I assume the unusual sideways angles of the valves are the result of a design intended to create as compact a combustion chamber as possible in light of the location of the cams in the case. Without the valve angularity the alignment of the valve train would be far worse. In this unusual K valve train the lifter bores are tipped toward the cylinders (IN and EX each set at different angles) and the cams are ground at these same complimentary lifter block angles too. If you look carefully at the image of the KHK cam lobe below you can see that the lobe face tapers towards you (is smallest near you) and is larger on the rear perimeter as you view it. Just more of the peculiar K model allure. Wish I had a side view of a cam lobe which shows the angle even clearer, but alas no side view.
LDB wrote:Have you ever measured a clean head that has not been touched in the valve area to confirm they are at an angle or have all the ones you've measured but cut deeper with the milled circles to one depth or another? Thanks.
Yes, head #1 in the study above is an unmolested as cast cylinder head, and has the same angles as the other 2 heads in the study. The machining does not change any angle, just deepens or widens the existing combustion chamber surface.