RE: engine roll- or dowel pins

[McNeon@domain.elided]

In my humble opinion, the roll pins don't help at all. The notion of O-rings 
"collapsing" makes no sense to me, since the oil pressure inside the O-ring 
is much greater than the (possible) water pressure outside (and there can 
only be water pressure present around the O-ring if the head gasket fails).

As for trying to remove the existing roll pins, that's a tricky proposition. 
I use a slide hammer with a drywall screw in it, which works fairly well. Be 
very careful if you try this trick, because one broken-off screw and you're, 
well, screwed. Remember, too, that the oil flow through these passages is 
very small. The first Alfa engine I ever dismantled had had its head gasket 
reused and sealed with silicone sealer - the oil galleries were full of the 
blue stuff, and the cam bearings were still kept alive by the seepage!

The main effect I've seen with roll pins is that it is harder to effectively 
clean the sealing surface around the oil gallery. My advice: leave the roll 
pins driven in flush with the block surface and be careful not to dislodge 
the O-rings when you install the head.

I'm not the final authority, but I have assembled a few dozen Alfa fours 
(including my race engine which runs 12.5:1 compression) and I've never had a 
problem with O-ring failure, other than a little eventual seepage.

Bob McKeown
Nashville, TN

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