301 poly rod caps

[44todd]

I have a 55 Cyrysler 301 poly motor, I know the crank is the same as a 55-58 331-354 Hemi, but wondering if the rod caps from the 301 will work on a 392 also??

[mart]

I have a 55 Cyrysler 301
poly motor, I know the crank is the same
as a 55-58 331-354 Hemi, but wondering
if the rod caps from the 301 will work
on a 392 also??

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Nope. First the big end diamiter is wrong. The big end
diameter on a 392 rod is 2.5 inches whiler the diameter
on a 301 Poly rod (and 331 & 354 Hemis and Polys) is
2.375 inches, - a full 1/8 of an inch smaller. With machine
work it's probably technically possible to do - although,
it's certainly not pracical and for the price of another
set of rods, I can't think of any good reason why you'd
want to do this.
Secondly, even if a swap was possible - you shouldn't
mix caps and rods anyway. Connecting rods are forged in
one piece and then the cap on each individual rods is
actually broken or 'fractured' off in a precision
press, the rod and cap drilled for bolts, then bored and
finish honed to the final diameter. Because each rod is
fractured slightly differently, the mating surface is
microscopically unique to each rod and cap assembly
and that cap should stay with the rod that it came off
of to maintain those original dimensions. If you
accidently mix up the caps and rods on an engine during
dissasembly, it's possible - more of an act of desperation,
and still not really a good thing to do - to use the
mis-matched caps and rods by re-machining the mating
surface, then bolting them back together and line
honing the bore back to the original dimensions. Far
better and safer - not to mention, much cheaper too -
to just mark each rod and cap before disassembly, so
you can put each rod and cap assembly back together
in the same order that god and 'Ma Mopar' originally
made them!

mart
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