Cary---If your late model head that has not been previously milled, then
taking off the .125 should get you near the 9.5:1 CR you're looking for.
The Triumph has a non-interference engine. In the valves-closed
position, the late, stock head and valve lift allows more than .600 of
piston-to-valve clearance, so you have tons of room here. Even in the
unlikely event of cam drive failure.
Other than several needle choices, there's little info regarding
performance tuning for the ZS carbs. If you leave the stock cam in, you
shouldn't have a need to change much in the way of carburetion.
The higher CR you seek will now result in having to use higher octane
fuel. (91 or so.) Your spark timing will depend on the octane, but for
starters, try setting it at 8 deg. BTDC at idle. (No retard connected
during the timing check) If you hear pinging under engine load, retard
the timing a little more till you get rid of it. You shouldn't have to
go under 6 deg. BTDC.
Dick
From:
caryhenry@hotmail.com(Cary Henry)
As most 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.
Thanks,
Cary Henry
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