With ref to intake port mods:
I modded a later arrow type head for my race car. I think these may be
narrower in the port than the earlier "tubed plug hole" heads, can anyone
confirm? Anyway, Vizards head book states an ideal inlet port size of about
.8 of the valve head size, which just happens to be the same size as the
exhaust valve head. So I just opened out the port evenly using an exhaust
valve as a guide. It was a much happier revver afterwards, though I also 3
angle cut the seats, matched the manifolds, and unshrouded the valves more.
I have another head here that someone has opened the inlet ports way out, to
about 0.9 of the inlet valve head size. It does work well at high revs but
is pretty lame below 3000. They have done a beautiful job though and
everything is matched perfectly. I think it may make a good race head with
larger valves installed as well to bring it back into proportion. Its hard
to know what each mod actually does unless they are done one at a time and
tested individually.
Greg
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 08:45:09 CDT