the factory put 950 cfms on a 340 on the show room, not even headers. Factory also put 800 cfm Thermoquads on stock 318's with single exhaust. I've done carb swaps at the track for testing. Click the link right below in my post and watch my very mild, low compression 318 with 318 heads run with 1200 cfms of carb on top, no headers, 2.76 gears and stock converter. My opinion again, 800 and don't look back.
