<VV> Solvent Test for Heads
Geoff Johnson
geoffj@unm.edu
Mon, 12 Apr 2004 08:06:25 -0700
The problem with hand-lapping valves is they establish a seal at room
temperature. As the Engine heats up and parts expand at unequal rates the
seal can not work as well. With a properly cut interferance angle valve
job, the valve is cut at a 1 degree difference of angle from the valve
seat. This creates a high surface loading, on a narrow band, that upon
engine operation, shapes itself to a correct angle and shape. At room
temperature, before startup, there is only a thin area of contact, that
may, before it has operated, allow a little tiny leak. If you are losing
compression on a professionally done head I would first look elsewhere such
as rings.
-Geoff Johnson
--On Monday, April 12, 2004 9:38 AM -0400 "N. Joseph Potts"
<pottsf@msn.com> wrote:
> By hand, I cleaned up and lapped one head to be liquid tight, while
> the other head, which had been three-angle ground,