Hey, Guys- Sometime ago, the question was raised as to what PCV valve was correct for these engines. Well, I have run across the definitive answer in the 1967 edition of the FoMoCo Ready Reference Catalog for parts & accessories, p. 170. For '65-'67 289 engines, the correct valve is C5AZ-6A666-A (Cross-ref. to today's no. is an EV-50). C6AZ-6A666-A is for 66-'67 410 & 428 engines. Would I be correct in assuming that running the wrong valve could cause increased pressure with the possibility of oil blow-back thru the dipstick tube and even front and/or rear main seals? Regards, Stan
