The 260 block has returned from the machine shop the second time wth no
tool marks in the cylinder walls & piston fits just a hair on the loose
side, just under 0.004" on the cylinder that had the worst damage. I have
decided to accept this rather than going for additional boring or sleeving.
This appears to put me in good company, as the piston fits shown in the
Tigers United article "A 350 Lunati for the Tiger" list piston fits at
0.0035"
>From this I have to conclude I should make the same horsepower ;-)
I have chose to go with the "Home Ported" rather than the "Twisted
Wedge" heads used on the Lunati. The porting is limited to eliminating the
various ridges & casting imperfections & matching the ports to the manifold.
This should be enough to make a significant improvement, as it surprising
how poor the port finish & alignment is from the factory. The areas at the
head to manifold interface are poorly formed & have casting flash & the
area from the valve seat to the port have ridges that show the limitations
of a quick factory machining with no hand work. Smoothing out these areas
should give me hundreds? of extra HP without the expense of real high
performance parts. Combined with a mild performance cam, but no where near
as mild as what Ford provided, I should be on the road & ready to embarase
Miata's by late spring.
Doug Leithauser
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