[Jack21]

As Hound Dog mentioned, SBF heads are aimed at 302/351 size motors and work well.

As you approach and pass 400 ci in a "Small" block, the 2.02/1.60 valves start showing their breathing limitations. One of the things we Ford Guys have in our favor over the competition is better breathing heads. Small block Chevy stroker guys with 383's and 406's would give their left nut to have a set of big block, big valve, canted valve heads to use. Well, we Ford guys do. On a Chevy they're not interchangable, on a Ford, they are.

351 Cleveland 4 barrel heads start showing performance improvements as RPM or displacement goes up. And they bolt right on to Windsor motors. Granted, there are other modifications that need to be made, but the circle track guys use this setup. Run some numbers on your 393 with 2.19/1.73 valves on Dyno 2000 and you'll see 500 - 550 HP.

Blue Thunder is now making aluminum versions of these heads with the problems inherent in the vintage Cleveland heads addressed. Coast High Performance and Ford Performance Solutions have the Blue Thunder Cleveland heads.