Best sandpaper to notch pistons using valve with sandpaper

[Strange Magic]

As an engine builder, it's very puzzling and disappointing to hear caveman style tactics being used to build an engine. You wouldn't drive a nail in a piece of wood with a cresent wrench nor would you try to eat your soup with a fork.

[dwedge]

Well hell. I HAVE driven a nail with a crescent, and eaten soup with a fork, and nipped 4.6l pistons with a Roloc disk.

[Mike Rogers]

[Dave Koehler]

This is nuts. Pull them out and do it right on a mill.

[Strange Magic]

This is nuts. Pull them out and do it right on a mill.

I thought it was just me that was nuts for a second. Like reading a chapter out of the twilight zone.

[bmcdaniel]

Sometimes you just do what you gotta to. In my own case mentioned above I had two weekend days to clearance the valve reliefs, put the new heads on and re-assemble, and put the motor back in the car before I drove it 700 miles one way to a meet. My car's not a racer or a trailer queen, I drive the crap out of it. Might have been done differently if I owned a milling machine with the correct cutters and a piston vice. But I don't. Guys have been using the Isky tool or similar tools to do this at home for many decades. Using abrasive material is just a take-off of that. It worked well on mine and the car is still running great six years later.