My Keith Craft 373 Yates engine runs a flat tappet camshaft with 185 seated and 450 open spring pressures, has 10.3.1 compression and made 675bhp on KC's Dyno, since then we re-dynoed here in NZ and this engine develops well over 600bhp on NZ BP98 octane fuel. The camshaft was run in using the outer springs only and I am running Delo 400 which has 0.15ppm of
Zinc until it has done approx 1500 miles and will then use a good quality semi
synthetic oil which has approx 0.15ppm
Zinc. I have Schubeck ceramic lifters which are quite expensive and dont like excess valve clearance, we looked at the camshaft after the dyno runs and no problems!
I guess keep an eye on the valve clearance etc, this engine developed max pwr at 6800rpm and in my lightweight cobra the engine should last a while changing around 6500rpm, naturally metal parts wear out and springs loose their tension, I would think it prudent to check and possible strip the engine every 2-3 seasons pending usage.