[VAC] Smoke and tears - Valve covers

["Carol and Oliver Filippi" <ofilippi@xxxxxxxxxxxxx>]

The reason the aluminum valve covers are prefered (easier to seal) vs.
stamped steel ones is that the aluminum variety are CAST and hence are much
more rigid along the flange which mates with the gasket and the head.  Thus
it is a lot harder for a gung ho mechanic to deform the valve cover by hasty
over or uneven tightening of the clamping bolts.  However, it is possible to
crack one by excessive or uneven tightening.

Steel valve covers do not have the same stiffness along the flange and can
deform more easily in which case they won't  spread the pressure along the
gasket surface, which is required for a good seal.

Nevertheless, with a little care and finesse, the steel covers can be made
to work fine.

Oliver Filippi