Cary,
If you go back to Kas Kastners Competition Prep Manual, you should find
the following numbers for head thickness and compression ratio:
Head
Thickness
(in) CR
------ -----
3.550 7.75
3.460 8.5
3.375 10.0
3.295 12.0
Plotting this up in Excel, a CR of 9.5:1 results in a head thickness of
3.400 inches. So my math says you would need to shave off 0.150 inch
from a 76 head, assuming it measures 3.550. But I would check your head
first to make sure it agrees with Kastners numbers, and in case a PO
already milled it. Indeed, you can check on the archives and you will
find countless instances of people going to higher compression with the
flat pistons, so 9.5:1 should be no problem as far as piston to valve
interference.
John Lumia - 76 TR6
Louisville, CO
Cary wrote:>
As all of you know, I have been having problems with my a leaky seal
between the head and the block on my 76. The coolant builds up on top
of the tab at the rear of the engine, so I am fairly sure the head being
warped is what is causing the problem. I put a straight edge on the
head, and it seems to be warped about 0.004" at some points. Instead of
diving head first into a full engine rebuild, I am going to rebuild the
head and see where that gets me. I figure at most I will be out a head
gasket set and 3 hours of my time. Since I am sending the head to the
machine shop, I will be milling the head 0.125", and getting a 3 angle
valve job. I plan on installing moss hi perf. springs, bpnorthwest
shortened pushrods, moss valves, moss valve guides, and bpnorthwest
alloy spring caps. I just wanted to make sure that there will be no
piston/valve interference by milling 0.125 from the head.
Also, I know the carbs will need tuning and most likely the timing, too.
Are there any links to some zenith carb tuning manuals??? Also, what
timing are you running with you're high compression setups??? I
understand that milling 0.125 should give me approximately 9.5:1CR, is
this correct??? Any advice on parts, etc. is most greatly appreciated.
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