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I believe the best upgrade for these engines is a free flowing exhaust. Much like the CIS injected Porsche engines of the same time period.
Make sure you have a nice clean exhaust flow and it should pay dividends at the top-end...but like MAG58 says it will hurt that low end torque.
Attached is a picture of the CIS heads and the spark plug location.
Only thing I could find was:
IN: 45.2
EX: 39.1
Engine Bore: 86.0mm
Engine Stroke:78.8mm
FYI, those are larger valves than a Porsche 911 3.2 engine had.
PS: Sorry for digging up an old thread, I saw it on a search.
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Nathan
'74 280C - gone to a new home for the finishing it deserves.
'64 356SC
'74 914 2.0
Last edited by JMURiz; 01-26-2012 at 05:07 PM.
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