[6pack] Compression ratio calculation (Was Headers)

[Foster, Stan]

The TR6 compression ratio was gradually reduced over the years from 9.5:1 (UK
PI) to 7.5:1 in 1974 (US version). I realize that there was a change in head
at least once during that time but was all of the compression ratio variation
achieved via milling the head to a desired thickness ?. Do we have head
thickness data for the various years and in particular my immediate question
is regarding the thickness of the standard 1974.5 circle B head.

Stan

-----Original Message-----
From: 6pack-bounces+stan.foster=hp.com at autox.team.net
[mailto:6pack-bounces+stan.foster=hp.com at autox.team.net] On Behalf Of michael
lunsford
Sent: Wednesday, January 02, 2008 6:48 PM
To: 6pack at autox.team.net
Subject: [6pack] Headers

Can someone out there refresh my memory about the best headers to buy for a
late model head (2 pipe exhaust).  I seem to recall that a lot of people were
unhappy with the fit and durability of the Monza headers.  I have an early 6
(1970) with a late model head and would like a few more HP (doesn't everyone).
Also, can someone also refresh my memory, or what little I have lert, about
compression ratios.  I thought that since I installed .020 over pistons the
compression ratio would go down (more volume).  Someone said it worked the
opposite way (bigger pistons-comp ratio goes up).  Which one is right?  TIA.

  Mike Lunsford, 1970 TR 6, Goodparts S-2 cam, 9.8/1 compression