<VV> Top Cover Gaskets/ Lose Screws

[Mark Durham]

Yes, there is a coefficient of expansion and contraction between
aluminum and steel, however, in the temperature range we have in the
block, its not that much. At mach 3, the British Concorde grew 18
inches in flight, try to seal that up!

Sent from my Windows Phone
From: Smitty
Sent: 6/25/2012 21:43
To: virtualvairs at corvair.org
Subject: <VV> Top Cover Gaskets/ Lose Screws

Sent from my Windows Phone
From: Clark Hartzel
Subject: <VV> Top cover gaskets/loose screws Another reason screws loosen up
is cover and block are aluminum and the baffle is steel.  They expand and
contract at different rates causing the gasket surface to "walk" back and
forth.  I never could understand how aluminum heads can work on an iron V8
block.  Lots of movement there!
Maybe we should make an aluminum baffle plate.
Clark Hartzel
*********************************
Smitty Says;  Sent from my 15 year old Dell PC.  Just for the record, the
use of screws when talking of bolts offends me.
Every time the subject of the coefficient of expansion difference between
the Crankcase baffle and the block and the block cover comes up, I hear
about how much slipping and sliding is going on between them.  I say bull
feathers.  That plate is not made of glass.  It has ductility.  It may not
like it much but it is forced to stretch and shrink with the materials it is
sandwiched between.  Like I have said before.  I haven't used gaskets there
for better than 20 years.  I mill file both sides of the steel plate to make
sure it is perfectly flat and then with the thinnest coat possible I apply
RTV to both sides.  Again I say, I have never had a leak there.  But then I
properly torque the bolts.  It is all I can do to keep from slipping into
sailor profanity when people talk about the gaskets allowing the pan to
slip.  Anyone who has worked more than a few engines has run into the ones
where the previous assembler liberally glued on the gaskets with Permatex
two and you had to all but break the casting to get it loose and then take a
chisel to the residue of the gaskets to get the crap off.  Where was the
slippage in that.  How many of you are aware that there is a difference
between Early and Late baffle pans.  The Lates are considerable thicker.
Why is that?  The general had a surplus of thicker metal?  I think not.  I
haven't turned out engines like Claypool or Sedman or Helt, but I have done
my share.  I have found enough Early pans with cracks in them to believe
that they simply couldn't keep up with the stress of the growing and
shrinking aluminum, so they made them thicker to handle the stress.

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