Stuart---A couple of the larger parts suppliers woud have us believe
that the unleaded fuel now available will lead to all sorts of problems,
if we don't purchase their hardened valve seats. I see no measurable
recession after about 15 years of this pump gas. This was confirmed by
the shop who did the last valve grind.
It is written that seats that are integral with the head (as original)
will do a better job of heat transfer (back into the water jackets) than
those pressed in. (Small air gaps that occur between the head and new
seats do nothing so far as heat transfer).
Shortening of the pushrods after a head milling is not "automatic". This
measurement starts at the cam base circle. I would wait to see where all
of this shakes out as the valve lash is being set. Kastner's new book
has a page or two about this, and a good investment when doing
performance mods.
Dick
|