Comparison-60's 427so vs New 427so ?

[Barry_R]

Those OE 427 blocks from the 60's were selected or scrapped, and very often repaired at the factory before they ever made it to the door. I've seen them with individual lifters bushed, odd sized bearings, and with weld or epoxy repairs in non-critical areas. I've seen cylinders so thin you'd swear you could use them as a lace curtain. Any machining issues were doubtless corrected before assembly - you would never know if they'd been pulled from the line and rehoned, line honed, decked or whatever. A volume OE casting and machining plant melts it's scrap. Modern SPC processes and cost containment methodology did not apply to that era.

The NASCAR and in particular LeMans programs were doubtless based on custom and/or hand selected/inspected parts at every level of the assembly. I have seen some very interesting internal components from that program that were far outside of the realm of "normal" FE pieces - and could still be considered radical designs today. Ever see a "forked" pin end connecting rod?

I suspect that the primary driver for the non-roller tip NASCAR rockers is weight reduction at the valve end. I tend to agree that the roll couple at the tip is quite small, but do not see how directional reversal inertia could be much of an issue due to that short travel - perhaps .080". The benefit of the roller tip lies in the pivot function - reducing side load imparted to the valve tip. Skidding or scrubbing is most likely the result of uncontrolled valve bounce taking the roller out of contact with the valve. Reducing the weight would help with high RPM valve control - something of a "Devil's agreement"...