Since I overhauled my 77 gas 2 years ago, I have had lower oil pressure than before.   It's mid-green range when working, barely out of red when idle.  Before overhaul it was clear to the right all times.

I'm looking again under the timing gear cover.  I know there are holes behind the cam shaft gear that need to be plugged, and if not, too much oil will flow out and the pressure will be lower.  

I had a shop do some work on the block and wonder whether they put back all the plugs.

I see 3 of these plugs in place, as they should be, behind the cam gear (have to rotate the engine to see them through the 3 holes in the gear).   

But I notice there is a 4th hole, threaded, not plugged.  It is near the top of the gear.  In my service manual, I can see it on page 2-6, figure 2-9.  It is to the left of the &quot;oil tube&quot; indicated on the photo.  Not immediately left, but about 6 gear teeth over to the left.

Looks like there might be a screw in the hole, in the photo.   Mine does not have a screw.  As I said, the hole is threaded.  Should it have a screw?

If I should put one in, any suggestions as to how I can get one in without removing the gear?

Thanks for any information.

Tom