[Land-speed] Valve cover gaskets

[Rick Byrnes]

Hi John
Sorry this is late, but still not up to speed yet.

I can't address the cork gasket for rocker cover, because I have only used a 
gasket with steel shim, and a silicon rubber sealing bead around the 
perimeter.  Obviously it can't be sucked in.

As for front and rear seals being installed backwards, front seals are not 
much concern because of much smaller size.  Some time ago the nascrap guys 
were doing this, but they got smart and started talking to the seal 
manufacturers for better alternatives.  Old single and conventional dual lip 
seals would leak air from the outside.
A look at Chicago Rawhide seal design shows that there are quite a selection 
of single lip seals with various sealing pressure available.
I originally went for a dual lip (the second lip is only to prevent dust 
contamination of the primary sealing lip)
This worked but was not low friction.
I now use a PTFE rear seal (4.0" Dia) with a lay down lip, that has a 
relatively high sealing load, but low friction by the nature of the 
material.  These are commercially available and work well with my Barnes 
latest and greatest pump.  I have not measured crankcase vacuum for a 
sustained pull, but will do so in the future.  I will be looking for front 
seals of PTFE because I still use three of them and when I shut the engine 
down, I can hear a high frequency sound that I think is seal lips vibrating 
as the pressures normalize.
If improved seals are not available, the sealing loads can be adjusted with 
slightly different garter springs.  This though will wear a little on the 
crank.  On our engines that see so little run time, I don't think it is an 
issue.  I was looking for low friction because my motor is on the "small" 
side....

Rick
Getting better every day in every way!