Re: 392 block was 345 block

[Doug Rasmussen <DougRasmussen@domain.elided>]

John L wrote:
>Now picture a quality machine shop of today.  After measuring the OD of
the
new pistons, the machinist sets up the boring machine to cut the cylinder
several thousands shy of the desired bore size.  He then hones the bore
with decreasing grit sized stones, all while carefully taking measurements
until the bore size is perfect.  I'd expect a good machinist could hit
tolerances of a few 10 thousandths without much trouble.  Far superior to
anything mass produced.<

John,

  That's my real curiousity, how close can the average competent automotive

machinist get those bores?   Honing a 4 1/8" bore to a few 10 thousands for
the
 price you're willing to pay doesn't seem realistic.  Honing is a
relatively
expensive operation compared to boring.  I always dread when we have to
have
anything honed, it's expensive plus the skill of the hone operator is so
variable.
 I doubt they could even reliabibly measure closer than about +/-.0004"
over the
 length of the bore.  But then,  those kind of tolerances aren't necessary
anyway.

  Not meaning to nit pick too much here, but I work with high tolerance
machining
all day long so I've wondered what the automotive shops can do.

Doug