Yet another question on my 468.The front oil galley plugs behind the timing chain do not have holes drilled in them but the face of the block where the upper timing gear rides has a small hole drilled in it(it goes into the oil passage that feeds the cam bearing) is this enough oil for the timing chain.Do the plugs need to be drilled to bleed air out of the galley for the hyd roller lifters?Im running a cloyes hex adjust with the torrington thrust bearing.Thanks Bill.

Bill,
Not Mike or Gary, but here is my worthless opinion :)
There does not seem to be any pattern from GM as to which engines got leaky plugs and which ones did not. I have seen about half and half when tearing engines apart. We put them in all the big blocks we do, it certaily cant hurt and as much problems guys seem to have with getting oil up top during priming, it may help. Pioneer actually makes a plug that is already drilled, part number PP454. Might as well do it while its easy to get to.
The hole drilled behind the timing gear is not factory, someone added it later and its probably a good idea seeing how rats tend to eat up the front of the block.

Hi Bill & Bill :waving:

What Bill said :D

What size hole is recomended on the face of the block behind the cam gear? Bob

I always drilled the plugs because a motor would bleed down the lifters overnite. It sure can't hurt the timing gear wear. I used a .040 drill on mine.