Racingjunk Forums - Max CFM from 049 or 781 BBC heads

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Max CFM from 049 or 781 BBC heads

What is the max cfm I can get out of these heads after we port them or just clean them up? thx

If I would do anything with those heads, it would be resizing seats and installing 2.19"/2.25' intake valves and 1.88" exhaust valves and open the bowls up under them.

Add up the cost of this and some port work plus combustion chambers and then bronze guides and you might be close to a set of bare RHS steel 320 heads that will perform better with little work. The price for the remainder of components will be the same for any head.

320 aluminum RHS or 325 Pro 1 Dart would be next step up. I have bought new castings on this site for $1200.

ok thanks. I believe they can flow 290-300 cfm but for the amount of money involved in machine work I may look for used aftermarket...thx MM