Recommendation Wanted: Valve Cover Gaskets

fratzog lover said

Dont forget the cylinder head surface it its an LA engine. These can be tweaked and sanded(easier when the head is on the work bench)to seal better than as cast from the factory. Look at the head rim with a magnifying glass and you may be amazed any gasket seals.

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I second that for my 1965 383. The valve covers have always leaked at the rear, dripping oil on the starter and exhaust manifold (for that smell of burnt rubber in the morning). I went whole hog w/ cast alum Holley covers and pricey silicone gaskets. The later were stiffer than normal cork & rubber, which made things worse. I finally noticed the cast surface wasn't flat and dropped down ~1/8" at the rear. I tried to seal there by first bolting down tighter at the rear, then force it down in front and ended up breaking the rear tab off an alum cover (trashing it). Next time I have the heads off I will mill a flat surface (like Magnum heads). Also, a ridge in the casting seems to backup oil like a dam, causing it to pool near the gasket surface. I tried removing in-car (many stuffed rags to catch debris), but will do better on the bench someday. Likely the same issues for LA heads, though haven't noticed my 65 273 leak yet.