FE engines are known for having an overly generous supply of oil slopping around inside the rocker covers. The FE design fed oil to the rocker arms through ports between cylinders 5 and 6, and 3 and 4 on the block deck (rather than through the pushrods.) Barry likes to restrict these passages somewhat, either on the deck itself using set screws with a drilled orifice, or on the cylinder head oil passages. This tends to improve oil pressure at idle. On race engines using a Jesel or T&D rocker setup, which are pushrod-fed, these deck ports are completely blocked.