Cubic Inch Displacement
To calculate the size of your engine after bore or stroke, use the following calc:

CID = bore x bore x stroke x 0,7854 x number of cylinders

For example: Lets say that you have a 396 big block wich has been bored 0,30. What CID would your engine have after that?
The 396 original bore is 4,094" and 0,30 bore on that will make it 4,124, ok? The original stroke is 3,76" so with these number we are ready to calculate. 4,124 x 4,124 x 3,76 x 0,7854 x 8 = 401,796 and that will make a 402 CID block. Simple huh? 

How big carburator do I need on my engine?
How To Calculate CFM:

Engine size (CID) x maximum RPM / 3456 = CFM

For example: Lets say that we need a carb on our new 402 CID engine. So how big carb do you need?
402 x 6000 / 3456 = 697,916 CFM wich will make a 700 CFM carburator.

Tommy Ledberg