Camshafts, I used the Good Parts S2 cam in one car and
the TR5 early TR6 PI cam in the other, both idle fine, I was
surprised, this with stock carbs. The former has 10 to 1, the
later 8.5 to 1. This is one place NOT to get carried away as
you'll likely want to mill the head again later and you start
stressing pistons, gas octane, etc. 9.5 to 1 is a good maximum.
(this gives you a little room for error and remilling).
Don't forget when you bore the engine the compression increases
due to the chamber ratio change... include this in your calculations!
Talking how much to take off the head is an error...
Use the final thickness of the head as the measure. These heads
came in differing thickness and may have been milled before.
(example: anyone want a 14 to 1 head, I have a spare...)
If you use the S2 or PI cam and moderate head milling the
geometry will match perfectly. These cams have a smaller base curve.
(see the mix of cams and pushrods part numbers for PI cars)
(believe PI or S2 cam and 9.5 to 1 head use the same pushrods as
US cars, better double check this...)
>putting .060" shims under the rocker gear to maintain rocker geometry
Wrong, this is just plain wrong, short pushrods is the only proper way
correct this, draw a diagram, this is obvious. THINK!
If you really mill the head, the easy way is to measure the geometry after
its done and order the pushrods cut to length... Brit Frame and
Engine will do this.
--
Roger G. Bolick, rgb@exact.com 512-794-9567, FAX 512-345-2879
|