You can open them if you like. Dont really think its necessary. Ive buzzed mine routinely to 7500 with no issues. Doing a quick freshen up on mine and except for some junk going thru a couple bearings, they looked good. I did get rid of the squirters. Im currently working on reducing the amount of oil that goes to the heads & lifters. I'm restricting the oil that goes to lube the the lifter bodies, which gets oiled thru the mds bores in the valley. I designed and made aluminum plugs that can take a set screw that can be drilled to change restriction size. I'm also putting restrictors in the cylinder head oil feeds. I'm running T & D adjustable rockers with a solid roller cam. Dont need that much oil to keep the rockers, pushrods & springs lubed.