Inner sactum oil galley plug

Jadaharabi said

The plug Mike is referring to is a pressin and that separates the two lines going to the oil filter. Without it you have real crummy oil pressure the other thing is before you replace it. You should take a long half inch drill bit and drill that passage to half inch because it is the main one that feeds your lifter galley and it is usually a bottleneck from the factory.

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Yes. I used to work in a manufacturing machine shop. You can only drill so far in with a drill and limited to the stroke of the machine and the length of the drill bit. Here comes the step drill procedure. The first hole is say 3/8, then you drill a couple inches further with a 5/16 and then a couple more inches with a 1/4. The last (larger) hole also gives the shavings space to exit the hole.