Pro tip: Folks, please stop doing this. I see it constantly on social media. This valuable 364 4 barrel intake is wrecked and has to be surfaced.. There is never ever a reason to use abrasives such as sanding disks or even those scotch bright scuffy rolox pads to remove gasket materal from mating surfaces.. They remove metal and ruin the gasket surface. It may seem like those scotch brite syle abrasive pads dont remove metal but they do, and they remove a whole lot of it before you even realize it, while rounding off the edges.. the other problem, is you are spreading/flinging contamination by using power tools. Especially on aluminum timing covers, Just use single edged razor blades on everything. Works perfect, and doesnt take as much effort as you may think. They come in packs of a 100 for cheap and it should be the only thing you use to remove gasket material.
