Joe,
I'm running 10:1 compression and have no problems. It depends a lot on
the cam you select as to what compression you should have. My cam for
instance has enough overlap to bleed off some of the pressure so detonation
isn't a problem if you watch your timing advance and mixture. I think the
only way to select pushrod length is to assemble the head to the block with
the gasket and use an adjustable pushrod to check the geometry of the
valvetrain . I took a stock TR6 pushrod , cut it, shortened one end and
threaded both ends, I then used a hex 1/4 x20 threaded rod coupling to join
the two( I also used a 1/4 x 20 nut to lock it together). You can lengthen
or shorten the pushrod till you have the geometry you want. I can't imagine
being able to do this without physically going through these steps. Be
careful with selecting your cam and springs , as these all should work
together, keep you spring pressure to just what you need, no more. These
cams are touchy!As far as pushrods, I went to Smith Brothers Pushrods,
http://www.pushrods.net/, tell them that length you need and you'll have
them in a couple of days. I believe they have two or three grades of
pushrods depending on what your doing . These are the same rods that are
sold by many performance TR6 suppliers but if you go right to them you'll
pay @ 1/2!
Good Luck let me know how it works out,
Nick Gemas
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