These are the TFS PowerPort 290cc intake runner aluminum heads with 74cc chambers, chromoly retainers. And a max lift of. Looking for serious Big-Block horsepower? Trick Flow PowerPort® 290 cylinder heads for Ford 429/460 engines deliver significant horsepower and torque gains over similar-style cylinder heads. The heads have Fast As Cast® runners that duplicate the port shape and profile of CNC-ported heads for near-CNC-ported power and performance for about the same price as regular cast cylinder heads. Other features include an extremely efficient chamber design for more complete combustion and exhaust ports raised. 270 from stock for increased airflow, Trick Flow PowerPort 290 cylinder heads are available fully assembled or…