I pulled my engine (small block 350) to replace a leaking rear main (I thought). With the rear main replaced, new pan and a nice Felpro one piece pan gaskat in place, I put in oil last night while its still on the stand and primed the pump to pressurize the oil system. Tonight I looked at the rear of the engine only to find some oil. Only its not coming from the rear main or pan gaskat. Its coming from the 2 inch plug in the block behind the cam shaft. My leak all along I think. I need advise on replacing it with the cam installed. I have never done one. Someone advised me to punch a few holes in the plug with an awl and use a slide hammer with a sheet metal screw and try to work it out. If there are any engine experts out there I sure would appreciate some advise.

That's exactly what I did when I replaced mine. I coated the edge of the hole and the edge of the plug with Indian Head sealer available from NAPA. Either use a socket or a race installation tool and tap it in flush, that's all there is to it. Good luck.