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 To unsubscribe or to change to a daily Digest, please go to http://www.airstream.net/vaclist/listoffice.html If replying back to this message, please delete all the unnecessary original text from your reply.
