Gaskets

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A friend once mentioned that on his Dual Valve there was no oil pan gasket because the mating surfaces were that precisely machined.

Is that true or did I misunderstand him?

I’m writing an article on gaskets and thought I’d mention this, if it were true. I suspect, though, that even Pierce Arrows used gaskets.

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That is correct, they did not use a pan gasket, they did not use a gasket on the timing covers either. If you put a pan gasket on one of those engines it will leak oil around the crankshaft at the rear main as now you have made extra clearance around the bronze ring that is supposed to seal the rear main. It will also make installing the front cover more difficult if not impossible depending on gasket thickness as the cover attaches to the crankcase and the pan, so if you move the pan down the holes may no longer line up. This goes for the early single valve, duel valve, and up through the series 36 engine.

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Many aircraft engines, as well as split-crankcase engines like the air-cooled VW engines also used just a sealant.

I do wonder what Pierce Arrow used as a surface-sealant?? Some type of varnish?

What I would use on a split crankcase that I suspected might not seal with brushed on #2 Permatex, was a single fine cotton thread. I’d put down a layer of #2 Permatex, then lay a single string of thread onto the surface, staying outside of any through-fasteners.. The very fine thread was compressed to virtually nothing, but would slightly fill some irregularities on not entirely true surfaces.

Greg Long

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