I use a Lunati Voodoo roller cam (201207-10LK) and Lunati roller tip rockers (85035-16). It is not a loping cam, but it does have some performance specs. The lobe separation and duration is 262/270 and lift is .507/.515. I don't really consider it a big cam. I wonder if the exhaust has any bearing on the size of the PCV valve as well. I am using the original heads and original 2.5" rams horn exhaust with 2.5" 'H" exhaust system.An engine with a big cam needs a bigger orifice in the valve because there's less vacuum to create airflow at idle.