Re: Oldsmobile oil system mods
 

What brand and part number lifters are they?

Re: Oldsmobile oil system mods
 

Make sure they are Oldsmobile lifters and not Chevy. The Oldsmobile/Pontiac lifters has the band and orifice at a different location.

Re: Oldsmobile oil system mods
 

Comp cams #863 lifters are a decent off the shelf lifter for these motors.
NEVER use a Chevy lifter in a BOP application as SSDiv6 mentioned the BOP lifter is taller and has the band further up the lifter. If you use a cam with a small base circle the band can be exposed at the bottom of the lifter bore with a Chevy lifter. Not only will you then have an oil problem but you loose support of the lifter in the bore and that could (will) lead to catastrophic failure. While were on the subject of valve train, guide plates are now legal for the Oldsmobile heads you don’t want to run without them!

Re: Oldsmobile oil system mods
 

As noted above, you don't need cam bearing oiling restrictors. However, don't drill new holes 180 deg. away or the original hole will be right under the bolt that holds the baffle plate. Drill the new hole around 160 degrees away and you will be fine. The Chevy lifters I have seen meter too much oil to the pushrods. With solids you can drill the lifter oil feeds to .135" and red loctite in allen set screws that you have heated red hot to detemper them and then drilled with a .040" bit.