I have a 73 TR6, that had an engine rebuilt about 8,000 miles ago, with the
car now being exempt from California smog regulations, I will be having the
following work performed on the cylinder head:
1. Having the head milled down to 9.5:1 or 10:1 compression.
2. Having the combustion chamber contoured and smoothed.
3. Valve seats ground to a 3-angle seat.
4. Depending on need, new guides, springs, valves, and etc.
I have the following questions that have come up and they are:
1. What is the thickness of the existing 73 head?
2. For a compression ratio of 9.5:1 what will be the required thickness of
the head? I have the required thickness for a 10:1 compression head (3.375
inches)
3. Are there aftermarket push rods available in the correct length for a
9:5 or 10:1 compression ratio? I notice that TRF sells two different length
push rods for PI TR6s that had 9.5:1 ratios, will any of these two lengths
work?
4. If the existing push rods can be shortened, is that a big deal and how
does the machine shop determine the required length for the 9.5 or 10:1
ratios with only the cylinder head available?
5. With only the above head modifications, what percent horsepower and
torque increase can I expect? Note, that I have already installed dual
Falcon stainless steel pipes with dual ultra flow mufflers.
Martin Gonzales
73 TR6 (a.k.a "the favorite son")
San Jose, California
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