Advancing the cam 4 degrees moves the powerband down several hundred rpm, at least in theory, retarding the cam does the opposite.Playing with cam timing isn't for big power gains ,it's a tuning aid. .My experience with a modified 261 has the power signing off at 4200 rpm and the engine pulls down low like the stock 261 in our 51.I advanced the cam 4 degrees when I did the engine, sounds good to me.
