oldsmoboogie

Battenrunner

Yes, you are on the right track. De-burr and port all oil drain back holes and any casting flash you see in the lifter galley area, port the oil return hole behind the camshaft timing gear.

Remove all of the oil galley plugs on the front and rear of the block, so you can see all the way through the oil galleys front to back, so that it will get cleaned out front to back.

The rear plug that feeds oil to the distributor gear must be removed and it is tough to get out, because it is a square plug and very tough to get the correct-sized square drive socket.

If you can't remove this one yourself, make sure and tell the shop that it must be removed before hot-tanking the block, and that they need to keep the plug and not throw it away.

You need to keep all the plugs that go into the oil galleys because they are all special straight-cut threads and not NPT threads.

scrappie

Wow, I never knew all that. I would've just given to machine shop and trusted they knew? Good info

BillK

Just want to add that if you cannot easily get the oil galley plugs out, especially the square drive one in back, please stop before you mess up the square drive hole in the plug.