i've found that stock (factory) valve covers don't fit worth a crap on edelbrock heads and 440 source is kind of a copy. i did find that the summit (or proform) chrome covers work great and those with the fel-pro 1610 have worked well for me. oil drain back in these alum heads isn't as good as iron. i massage the drain back holes in the heads and have notched the block some to prevent ponding.