TeriAnn,
Why does it seem like you don't think the early unchamfered head should be
used with anything other than 83mm pistons? While I have not had time/funds
to complete my TR4A, 1.5 inch intake head, I have been running an unchamfered,
unmilled early head with my 87mm pistons; with a stock composite head gasket.
Since I figured using the old head was a short term situation (bad assumption)
and knowing it had never been milled, I knew it would be pretty safe with
regard to CR. Unfortunately, I did not take the time to measure the chamber
volumes to calculate CR. I did notice the difference in the absence of a
chamfer on my "old" head, but it didn't register that it was different until
after the car was back together. Just curious if you, or anyone else, might
have an idea of what the old, unchamfered head and 87mm pistons might do to my
CR. I had figured the 87mm pistons took the CR up to around 9:1, maybe a bit
higher, but with the unchamfered head, I wonder just how high it really is.
Regards,
Jack Brooks
>>From your description, I believe that this is the second high port intake
>manifold casting, intended for use with 83mm pistons. If you are running
>83mm pistons or want the higher compression you get with 86/87mm pistons
>and no combustion chamber camphor I believe this is your head of choice.
>It has more metal between the bottom of the head and the water jacket
>than the earlier casting. You can safely mill it for higher compression
>with 83mm pistons.
>
>To make things even more interesting, the factory made 86mm pistons an
>orderable option starting sometime in 1957 (I have a photocopy of an
>Standard-Triumph parts list addendum that shows the part numbers for the
>86mm pistons). So there should be early heads of some kind with a
>camphor on the edge of the combustion chambers.
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