Obviously someone scraped and damaged the pad. I believe the 409 did not have the traditional small/ big blocks, fore-aft broach marks, although there were circular machine markings. Hopefully a 409 guru can shed some light...

That is pretty sad, scratching lines with an awl or something. I went through this with Verne a couple years ago. Apparently the relatively small volumes of 348/409 engines didn't justify the expense of the big planing machine that did that operation for the small blocks (and later big blocks). Thus production used a rotary machining operation for preparing the 74 degree deck surface of the W motors.

Looks like that would be easy to copy.

I’m not sure-they look kinda like regular broach marks where none of the lines intersect. You’d have to use a very large diameter, uniform grinding surface that came down on the surface flat and didn’t move laterally.

A friend of mine has a machine that is used for resurfacing heads and blocks that makes the same pattern when it cuts. It has a large wheel with carbide inserts. It made that same pattern on my heads when we cut them.

This one is back on the block for $53k - in the link below.

Link to 1963 Impala auction

https://cdn.dealeraccelerate.com/cmc...evrolet-impala

West Chester. My Alma Mater and still only 25 mins away :)