Hole in the Head Question

[SpearsEng@aol.com]

The shop has installed the new head on my 1600, however there is a hole 
(about 1/8 inch diameter) in the head on the passenger side by #4 cylinder.  
This hole is pumping out oil like no tomorrow.  On the old head this hole was 
plugged with a piece of brass.

What is the hole for and what goes there if anything?   Also if we need to 
plug it, are there any suggestions on how to?

J. Frank Spears
69 1600
Auburn, WA