331 engine rear oil/water expansion plugs

[Dave Gillingham]

Hi-

I am trying to finish a rather lengthy rebuild of a 1949 331 engine.  I have it mostly back together, but am a bit confused about what appear to be three openings at the rear of the block.  One of the openings is clearly related to the cam, and I have what I believe to be the correct expansion plug for it (1- 47/64).  Another opening is only about 1/2" in diameter, and it appears to have a plug in it already (evidently when the block was machined they left the original plug), and it appears to be "peened" in at three spots around the perimeter of the opening.  The third opening is more confusing.  It appears that there should be an expansion plug - approximately 1-1/8, but I am not sure.  Will somebody tell me a) what this opening is for, and b) whether an expansion plug is required.

Thanks!

Dave Gillingham

[Dave Gillingham]

I have uploaded a really bad picture showing the part I am worried about.

Thanks,

Dave Gillingham

[Dave Gillingham]

OK guys.  I figured it out myself.  The midsized plug to the left of the cam plug is an oil expansion plug.  It is not referenced in the catalog I reviewed at the engine shop.  I found the answer by dissecting a core block I had.  Don't know the exact size, but I measured it at 1.11"

[The Tassie Devil(le)]

G'day Dave,

Good news to hear that you solved your own problem.

I couldn't help as I have never had one of those.

Bruce.