Richard,
I presume that by "intake" you mean total valve lift. .430" lift is
quite a bit more than stock. I would use bronze guides and would try to
obtain exhaust valves that have hard chromed or "plasma coated" stems. We
use .0015" to .002" valve stem to guide clearance on the inlets & .002" to
.0025" on the exhausts. Valve spring pressure with the valves closed should
be 85 to 90 psi. You need to make sure that the spring you use do not go
into "coil bind" at full valve lift. With the valve fully open, you must be
able to stick a .040" feeler gauge in between the coils of the spring.
We still "grind" all of our valve seats, and then lap them with fine
compound to make sure we have a good seal. I guess we are "old school". We
generally use seat widths of .040" on the exhaust & intake with hardened
valve seats installed in the head in both intake and exhausts. I like to
use 4 or more angles on the valve seats, 15, 30, 45, 60, & 75 degrees nicely
blended to form as much of a radius as possible. The hardness of the seats
prevents the seats from wearing or "pounding" and changing shape as the
engine runs. The most critical area in a head's ports is the 1/4" or so as
the seat "blends" into the "throat" of the port. That area critically
effects the flow of the port and the valve seat. This is not to say that
other areas of the ports are not important. But on an engine with a cam like
yours, you could spend a lot of money and time for very little effect. The
hotter the engine is, the more important the overall flow of the head and
manifolds becomes. On a full race engine, ie cam with over 295 degrees
duration, compression over 12: 1 and a power band going up to 7,000 rpm, a
lot of power can be picked up by working on the exhaust port flow of the
TR-4 .
Greg Solow
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