Vent Tubes SBC

[DCarr511]

Are Vent Tubes in the lifter Valley still being used in SBC's ( and others ) ?

 This would be for a solid roller cam, wet  sump with a good oiling sytem. Used for LSR and somewhat of a Street Car

I am hearing info on both using and not using, Those using say still say it increases HP and those that dont run them say it doesnt do anything.

I know of many who have machined boxes to block off the long slots over the cam in a BBC for the same results, so it seems something must be there.

[doug odom]

They drain back holes are to lube the camshaft lifters at low rpm. With a roller you don't need it unless you are going to let it idle for long periods of time. The oil dripping down on the camshaft does very little to hurt horsepower but there has to be some loss.
The main reason I block them off ( not vent them ) is to make all the oil go out the front or back of the valley where I have screens to keep trash out of the oil pump pickup. One roller rocker needle bearing will jam a wet or dry sump oil pump.    Been there - done that.

[promachine]

On a flate tappet cam I would leave them open, flate tappets need all the oil they can get. I use the vent tubes on rollers with a dry sump and a sucker line in the valley. If you are concerned about oil droping down on your rotating parts you can plug them but I would recamend drilling some oil holes in the bottom of your main oil galleys to lube the cam and lifters. You could also drill and tape them for holley jets or 1/16 pipe plugs with .020 holes in them. I hear that some are using the lifters with the edm holes in the bottom that work well.
Also you could grind a flat in the side off the lifters from the oil groove to the bottom, carefully! Good luck.