Cigarette Seals

["Tom Sanor" <mygoose@domain.elided>]

Many years ago I learned this improvement from someone, and I've used it
successfully on all my  Alfa engine rebuilds:

Instead of using the hard rubber cigarette seals, torque the bearing cap in
place then tap the holes down around an inch with a std. 3/8" thread tap.  At
the hardware store obtain a length of 3/8" threaded rod and saw off two pieces
around 1/2" or so in length.  These will be plugs for the newly tapped
cigarette holes.  On one end of each plug cut a screwdriver slot with a
hacksaw.  At this point clean up the threads, and also unbolt and remove the
main bearing cap and clean up there, too.

Now reinstall the main bearing cap (for the final time) and torque in place
and lock down, being certain you can screw the plugs in below the top of the
cap edge.  With the plugs out, fill the cigarette holes up but not all the way
with a good GE or Dow Corning 100% silicon rubber from a tube, being as
careful as you can not to trap air bubbles.  Now screw the plug into the wet
silicon rubber down to flush with the cap surface.  Wipe up any silicon rubber
the comes out the cracks.

Let engine set for a month(!) if possible so the silicon can cure, then screw
the plugs down in another 1/8" or so.  This puts a final compression on the
cured rubber in the cigarette holes.  Finish by smearing silicon rubber on top
the crew slots up to flush with the cap.  That's it, so now finish the engine
rebuild.  One could use metric threads; I do not because we can't readily find
metric rod stock in the US.

Note that I always enscribed a message nearby on the smooth pan mating surface
of the block with an electric etching tool WARNING any future engine builder
of what lurks below the exposed rubber in the cigarette holes.

Works great.

Mr. Goose
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