BradH made me think of this question with his oil/bushing post..

What size hole do you drill into the lifter bushing on a RB block, when you're running a solid roller with pushrod oiling?

The oil passage from the #4 cam bearing has been blocked already..

Thanks in advance..

I'll take a s.w.a.g and say .060", but I don't have pushrod oiling and am concerned only w/ getting oil into the bore for lifter lubrication.

First thing is to figure out where the restriction to the top end is going to be and then go from there.

The hole in the bushing can be the restriction but I wouldn't recommend it since it can be easily plugged up with debris and there is no easy way to do a clean out.

I think the best system is to use the clearance in the lifter bore as the restriction. But for that trick to work you have to use the correct lifters.

The location of the hole can also be important depending on the lifters.

The 2 blocks I have had done I had .125 hole drilled .

The location of the hole can also be important depending on the lifters.
X2 - I don't know of any bad choices in particular, but you should compare the tappet "waist" position and OAL to your tappet bores, allowing for whatever base circle and lobe height you'll be using.

I vote .043"

Thanks guys for the answers and I hope I'm going to be OK.. The machine shop that installed the bushings drilled a large oil hole in then. They had the cam and the lifters before the install and our agreement was they were going to do a measurement for hole placement..

Unfortunately.. we never discussed what size hole and from my estimation.. it looks like .125 or bigger..

The lifters we're using are the ISKY EZ with pushrod oiling and the rockers are T&D individual shafts, as we had the rocker stands turned down..

We're still about 2 weeks away from final assembly and primer of the oiling system.. but unless someone flat out tells me its wrong and needs to be re-done, then we're going to go forward and watch how much oil comes out of there during the priming..

Jeepmom, I think at this time it would be much easier to change the hole size in your push rods then rebush the lifter bores if you are getting to much oil to the top end.

I put a .062 hole in the bushing BUT I'm running
holes in the lifter to oil the axle and feeding the
rockers via PR so I went with a little larger bushing
hole... I think the axle feed hole is .015 and I have
.040 restriction holes in the PR... I havent fired it
up yet so I'm not sure if I will need to go to a high
volume pump... I will see soon.... this is a 416ci

Just out of curiosity.. does anyone know how large the oil passage in the bore is.. before it was bushed?

Before bushing the lifter bores on a factory Mopar big block, the oil area is very large. It is formed by the intersection of the oil galley and the lifter bore on the edge of the lifter bore.

I would estimate the opening is roughly .25" x .50", maybe larger.
That is an area of .125 sqin. So a round hole of the same area would be 0.40" dia