[Cobra-Radjah]

Duane,

There is a way to calculate the flow demand of an engine, based on a nr. of engine specifics, such as bore, stroke, compression ratio, con-rod length, flownumbers of the intake manifold and the cyl heads, cam advance and duration (at 0.05") and the desired RPM. If you post these properties, I'll be happy ro run them through my calculator.

Off hand, I reckon that even 2 - 450 CFM carbs ma be a little big for a 390 street cruiser. Holley usually recommends to stay a tad on the small side for better respons and accelleration in the low and mid range, sacrificing a little at the top. However, properly set up, dual 450’s should work just fine.