The CJ:R cylinder heads are available in either cast iron ($875) or aluminum ($975). The CJ:R has Cobra Jet intake with BBC race exhaust ports. Like the F460 head, the CJ:R also maintains OE 429/460 stock factory valve angles & spacing. CJ:R cylinder heads use any standard 429/460 wedge flat top piston. OE 429/460 guide plates and stud girdles fit perfectly. CJ:R flow numbers are indicative of very efficient CJ ports with intake flows capable of 350cfm @.600 and 375cfm @.900 with 2.25” valves (318cc runners). The BBC exhaust is capable of 240cfm @.600 and 285cfm @.900 with 1.71” valves (138cc runners). Has 74cc combustion chambers.Designed with engine builders in mind, CJ:R heads may be purchased blank; i.e. no seats cut or guides sized.