I just started my 331 motor with Canfield heads today and ran it for about 5 minutes to warm up so the thermostat could open and I could check for leaks!! What I have is a new set of Ford Racing valve covers without the breathers,because you have to buy them seperate.I also did not hook up the pcv because of the new valve covers.I have a 331 with 54CC chamber Canfield heads at about 11 to 1 compression ratio!! I started it up and ran it for about 5 minutes and have a tremendous amount of crankcase pressure{blowby}.This motor is a DSS Bullit Racing motor and don't remember this happening before with the cast iron heads!!Had the pcv system hooked up when starting that motor brand new,and it was also a 331 from DSS Racing.They just reworked it for me cause I dropped a valve with my cast iron heads!!Had paper towels in the grommets of the valve cover because I don't have the breathers yet.Also no pcv valve hooked up.It's blowing oil out the dipstick tube[WITHOUT THE DIPSTICK IN PLACE}because the dipstick hits the DSS main support system at this time!If I hold a rag over that hole it pop's the paper towels out the valve cover that I have in place of the breathers at this time.DSS told me I need to run the motor for at lease 45 minutes to and hour and the rings will finally seat in.These were the ductile iron rings I'm using with my nitrous!! Please give me your opinions on this!!THANKS,[email protected]