All the 230 and 250 Comp engines we did for guys that was the first thing we checked on the cranks was how much metal was around the crank flange to see if it could be drilled and tapped to 1/2". Most of them can, but there are some that won't because the bolt circle is too close to the OD of the flange. Drilling them to 1/2" won't keep them from backing out if that's what your thinking. That wasn't why we did it.
