427 or 428 - How do I tell?

[Excaliber]

I wouldn't wind a 428 much beyond 6,200, 6,500 max, and not that high very often. No way 7,500. But perhaps you could get away with it,,, for awhile. The 428 block tends to crack along the main journals at high rpm.

The 427 block was not only a four bolt main but used a different and complicated casting process as well. The bore was just about as big as it could possibly be and was thin walled. The bore size is why you can run larger valves, the cylinders still require a clearance notch for max size. It was good for 9,000 rpm in a drag racing application and was the base block used for the infamous SOHC engine. With the NASCAR crank mod's the 427 could run 7,000 plus and hang together for a 500 mile race. I've heard the rpm was limited to 6,500 or lower for the Le Mans 24 hour efforts. High rpm is an engine killer.

I'm running Le Mans rods in my side oiler and it has frequently seen 7,000 rpm. And sustained 6,000 to 6,500 on a road course. It tends to puke a little bit of oil out the valve cover vent at sustained high rpm, I think my oil level may be to high.