Omegabenz,

Sounds like old wives tales. I've had Diesel cranks reground and they worked fine, however they were not cranks that were nitrided. Why would regrinding affect oil pressure as long as the correct oversize bearings are used.

A 617 crankshaft is nitrided to make the surface super hard. I don't know how deep the nitriding goes but it is only a surface hardening. So if you grind away the hard surface, it should be renitrided. This may be the crux of the problem as I don't know how many shops are set up to renitride crankshafts. You might need a shop that works on aircraft cranks because some of them are nitrided.

P E H

PS: I don't know how this reply got placed before your question.