My 440 with aluminum heads has had a consistent problem with intake manifold gaskets leaking and sucking oil. I have tried gluing the paper six-pack gaskets on, all kinds of gasket sealer, and so on. I’m tired of taking this apart. Is there a proper method to find out why it won’t stay sealed?
The problem you describe is most likely not the fault of gaskets, it is related to fitment of the heads to the block and manifold. Think about it: The deck height, the deck angle, the head geometry, manifold angles and dimensions, are all really variables. As a block get cleaned up, aftermarket heads fitted, various aluminum intake manifolds, etc., there can be a tolerance stack-up which can make proper sealing almost impossible, especially as the aluminum components expand and contract with temperature variations, breaking whatever seal may have existed. Along these lines, you note that most modern gasketing systems (newer engines) are designed to stay sealed even with movement (O-rings, graphite coatings, etc.)
What you need to do is check the geometry and sizing of all these components. The crew at Hughes Engine Service (hughesengines.com) has developed a straightforward procedure for this. Rather that repeat it here (and fill a half-dozen pages on a prosaic procedure), just surf over to tinyurl.com/seal-intakes and be amazed.