RE: engine roll- or dowel pins

[bearbvd@domain.elided (Greg Hermann)]

>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.

Agree--but I have always felt that the square section O-rings which Chevies
use for valve stem seals work better for the job than the round section
Alfa parts. Never had them even seep.

Regards. Greg
>
>Bob McKeown
>Nashville, TN

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