Revving the engine with no load isn't as good idea. If you do that, keep it under 2500 RPM, but even then, it serves no purpose other than entertaining you. It won't tell you a thing about the performance under load since the carburetor mixture will be different, manifold vacuum lower, different vacuum advance position, etc.
No-load revving WILL put unneeded strain on the rod bearings at the top of the exhaust stroke when the pistons have nothing opposing their inertia. I'd suggest dropping the oil pan and inspecting the rod bearings, and keeping your greasy grub grabbers off the throttle in the future!
Jerry
