Message text written by "Bob Nogueira"
>Is there a way to tell how much has been milled off a TR-4 head. I have
several spares and the guy that gave then to me told me one of them was
milled for racing but it turned out to be high a compression ratio for
street use. I need to insure that I don't use that one for my street car.
Thanks for any advise as to what to look for in comparing the heads
<
I seem to recall (that book is at home at the moment) that Kas' book lists
dimensions from the mating surface to the valve cover surface for the low
and high compression heads. If you measure this with a pair of calipers
you can sort them by compression ratio. And if you know that one head is
shaved for racing and the others are not, this may be sufficient. But to
know what that ratio really is you need to measure the combustion chambers.
This is the only reliable way to know.
The way you do this is invert the head with the valves and plugs fitted (at
least in one cylinder) and measure how much fluid it takes to fill the
chamber to the level of the mating surface. Acetone or some other similar
solvent has been recommended since it will dry and leave no residue.
Dave
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