"Additional advantages of PowerPort 240 heads over stock heads include clearance for 3/8" pushrods, ductile iron valve seats, bronze alloy valve guides, and multi-angle valve seat machining on precision Serdi® equipment. Assembled cylinder heads come with premium 11/32" stainless steel valves, Trick Flow by PAC Racing valve springs, chromoly and titanium retainer options, and 7° or 10° steel valve stem locks."