My 340 build

MoparMark91 said

So you got a point there rusty, so i did think about cometic but...my ra i didnt believe would be good enough on the surface, and ive ran felpro before and no problems, along with others that sware by them. My block did get machined but i dont think it would if bern suffice for the gaskets, this is my first performance build so i figured felpro has done me goid in the past why not slap em on, plus i have to slow down and wanted to budget somethings cause i still need a new rear end lol......also the wife came across my receipt stack for my build .
D'OH!
Honestly wish i could run em withoutout worrying about the ra

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FWIW, there isn't a gasket out there that likes a rough surface. Not one I can think of. The idea of a rough surface "biting" into the gasket is just plain nonsense.

That said, some gaskets are much more forgiving of a rough surface. The Fel Pro is one of them. MLS gaskets really need a mirror finish. They can be a bit rougher, but not much.

The composite gaskets don't really don't like a rough surface either. When those fail from a wrong surface finish you'll find many or most of the head bolts loose. Most people blame the gasket for failing, but the gasket isn't really at fault. The rough surface literally grinds the gasket down to the point the fasteners are now loose.

People don't think that the head and block don't move. But they do. More than most think. All aluminum engines have the most movement, and bi metal engines are very hard on gaskets.

Not only do the heads move around on the block, every time a cylinder fires, the head literally lifts off the block. Every single time. So the gasket has to move in 3 axes.