Hi,
Just for yucks, I put this chart together. This is the cylinder volume for
variouls TR6 bore/stroke combos. To figure compression ratio, you need to
calculate the volume of your combustion chamber plus the volume of your
head gasket... it seems to me that there was a chart with the CC volume of
various 6 cyl./ Triumphs out there on the web, but I can't seem to find it
right now. At any rate (note - there is some rounding in the
calculations):
Bore    Stroke    Capacity  Cap./Cyl   + Size
2.940   3.740      2500cc   416.67cc    Stock
2.950   3.740      2510     418.33      +.010
2.960   3.740      2530     421.67      +.020
2.970   3.740      2550     425.00      +.030
So, a .030 over TR6 with a head milled and messaged to 42.5 cc's will
yield a 10.0:1 compression ratio (exclusive of the volume of the head
gasket which would be about 3 cc's.)
regards,
rml
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