Guys just take the rocker arms off when storing engines, plus you do not get the moisture coming in from the open exhaust valves, simple concept.
I built a dumpster 318 last winter for my next project, did not even bother to put he push-rods in it, because it will be a year or so before I fire it up, unless I get a wild hair and put it on my engine start stand.
Anyways, years ago I made some exhaust cover flanges out of .063 aluminum, using a header gasket as a template, I bolt them on engines I store, to keep moisture out.
Plus I use cheap saran-warp from the store, and wrap the crap out of an engine to keep moisture and dirt out, then cover with a barbecue grill cover.
It will keep the moisture and dust out of an engine.
I have a problem with the out-building I store my engines in, it is almost too dry, wasps and mud-dobbers love to build nests in everything.
