427 acceptable sonic check #'s ??

[momarkmach1]

What is the minimum cyl. wall thickness the experts feel is safe for a 12.5 to 1 mild drag race motor ? I had to finish the 68 427 SO bores at 4.260 , .028 over standard , I assume a higher compression rate raises the minimum cyl. wall ???
I will have it sonic checked , I know now that should have been the first step . It was thought to be only .004-.005 over but taper and out of round and honing stock took it further than anticipated . It is stamped HP , has the X in lifter valley and appears to be a high nickle block , late 67 date code . I need to know if it will be ok to build and race or save for a milder street motor and get a Genisis thick iron block for the drag project .

Thanks

[blykins]

I would stay at least .120" thickness on a higher horsepower, high compression engine.

I doubt you'll have that with a .030" over 427. My guess is that it will come in at around .090".

If it were mine, I'd use it for something in a street application (if it still checks good for that) as 427 S/O blocks are getting harder and harder to come by everyday.

BTW, pay close attention to the thrust side of the piston.