Putting the copper tube into a 440 block to cut oil off to lifters.
It,s been so long since I have done this can't remember if I opened up this hole up to 9/32. It goes directly into the oil feed from the pump to passenger side lifter galley.
Thanks

the passenger side lifter galley oils the mains, dont you need to oil them?

Yeah they will oil after you put the tube in and back drill the tube- oil will be in the tube
Just wanted to know about opening that hole from around .260 dia to 9/32?

I'm sure it's better but already done three years ago and no problems.
I just can't find that old paper from Mcandless on the B RB motors-- I know its somewhere.
I'm goin ahead and opening it up any how.
Thanks

I would not open up the feed hole to the #1 main. I would however open the feed hole up to 9/32" on #2,#3 and #4, but again leave #5 alone. The feed hole to #2,#3 and #4 mains feed 2 rods each and #1 and #5 only feed one rod each, so the hole should remain the same to help more oil to go to #2, #3 and #4. If running a solid flat tappet or roller, I would also turn the oil off to the drivers side lifters by plugging the hole that feeds it. It has the access hole outside the block opposite the oil pressure gauge hole. Some worry about turning oil off to the drivers side but I have done it many times with out any issues. You could drill a .04 hole in the plug so the driver side lifters see a small amount of oil. One last thing I also would do, is drill a new .080 hole in the cam bearings on the opposite side of the hole already there. Then line up your new .080 hole with the hole in block. You can only do the #4 cam bearing if you are externally oiling the rockers such as Indy Heads.

Thanks, always blocked oil to drivers side lifters too with plug and haven't drilled a hole in it yet all three have run for 25 years without problem. Already drilled #5 so what the hell and do #1.
Thanks for the info