What is the lift on Chevy 470 cam when you change rocker arms to 1.65?

You can't simply calculate the lift of a Chevy 470 cam with 1.65 rocker arms without knowing the cam's advertised lift. The advertised lift is the lift at the valve, *before* the rocker arm ratio is factored in.

The rocker arm ratio increases the valve lift. To find the new lift with 1.65 rocker arms, you must:

1. Find the advertised lift of the Chevy 470 cam: This information should be available in the camshaft specifications from the manufacturer (e.g., Comp Cams, Crane Cams, etc.). It might be listed as "gross lift" or simply "lift."

2. Calculate the increased lift: Multiply the advertised lift by the rocker arm ratio (1.65).

Example:

If the advertised lift of your Chevy 470 cam is 0.500 inches, the calculation would be:

0.500 inches * 1.65 = 0.825 inches

Therefore, the lift at the valve would be 0.825 inches with 1.65 rocker arms. Remember to always use the *advertised* lift from the camshaft's specifications, not any other value.