I run a stock oil pump at 70 # at 7000 rpm
I ran 13.5 to 1 for years with no problem, Single carb manifolds restrict
breathing somewhat. Texts suggest above 13.5 to 1 principally you gain
unreliability. Spun a bearing when I hit 9000 with a bad shift. But no other
problems. Tuning that crank down 0.010 on the rod journals and building it
back up.
Last year I ran a new engine with 15.5 to 1 with no problems other than I
generated more heat partly from the engine an partly from a re-routed oil
pump relief system
We have put a lot of effort into the bottom end with a stock forged and
nitrided crank.
Matt Matthews SCCA FP 1500 Spitfire
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