Re: Head Gasket

[Hirsch <Catenary@domain.elided>]

Mark Tamas wrote:
 =

>> ... When I pulled the head I discovered that 3 of the
"square-cut viton O-rings" that came with the headset had
split at the gap of the roll pins that were previously
installed on this engine. The job was done 3 years and
15-20K miles ago.
 =

My theory on the coolant leaks is that the roll pins are
too high and preventing the head from sitting down on the
block. The seal at the cylinders appeared to be just fine.
Is such a condition possible? <<

If the roll pins are too high and the head is torqued
down, the roll pins should be pushed down further into
the oil passages. The roll pins should NOT be installed =

so tightly that they prevent the head gasket from
seating properly. I guess it's possible but seems unlikely.

The subject of engine roll pins came up about 8 months ago.
My summary of that discussion can be found at the i Saluti
website at:

   http://www.geocities.com/MotorCity/Downs/3837/rollpins.html

>> It seems to me that these roll pins are causing problems
rather than preventing them. They certainly didn't help the
o-rings live very long. It also looks like they may restrict
oil flow to the head. <<

Although roll pins restrict oil flow, this apparently does not
lead to any oil starvation problems (see "rollpins.html" for
support for this statement.)

>> I'm thinking of removing them if I can. <<

How do you get these things out without destroying the head?
They're difficult to grab with pliers and if you use an easyout,
you can break the roll pin (or the easyout) and any metal shards
that enter the oil passage end up in the oil pump gears or the
camshaft bearings.

I think the best solution is to leave the roll pins in place
and as Simon Favre suggests, use Chevy valve stem seals in
place of the O-rings. These are O-ring style valve stem seals
normally used for pre-1986 small block Chevy (SBC) motors
(NAPA # B45229).

Good luck,

Rich Hirsch
St Louis, MO

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