Mike....
Normally, at a high mileage, ring wear to
some extent has taken place. So it is so
with valves, valve guides, etc. as well.
Matter of fact, on aircraft piston engines,
"top overhauls" are noted for causing
possible imminent "bottom" end problems.
when many hours are on the engine.
FUZZY (Larry Pitts) is an aircraft mech. so I'll defer to his wisdom as
this is really his forte....after all, pilots can only
break aircraft while mechs. fix them!
So, it can be expected that if you renew
the seal at the "top", you MIGHT increase
blow-by out the "bottom" (by the rings).
A lot depends on the sealing condition of
the rings before the head is taken off. I
suppose a leak down test prior to head
removal could tell where the compression
is going, if at all, to one extent or the other.
OTOH, I would think Mazda engines are better quality toleranced than our
Series A's. Maybe the Miata list is a better
place to ask this question of those with
experience and knowledge of this engine,
in view your engine's specific mileage?
Cap'n. Bob
'60 :{)
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