Since you asked I went
out to the garage and measured -- the HP stamp is
slightly larger than
the S 41 stamp -- I'd guess one font size. The S 41
stamp and the date code
stamp are the same size.
By the way, HP blocks
are a different casting blend than standard blocks --
higher nickel content.
HP blocks also were heat treated for stress relief.
HP blocks were built in
batches, separate from normal blocks, so they were
not pulled out of the
production line for performance modifications. HP
blocks sat in a group
in the warehouse until they were pulled for the
production line, which
is why the date stamp on an engine can be much
earlier than the car's
build date.
You are correct in the
way the Chrysler blocks are cast. All 413 blocks, and
others, are cast out of
the same material with high chrome and nickel
content. More than the
other car manufacturers blocks & heads contain.
Blocks and heads coming
out of the foundry are cooled then reheated for
stress relief. Then
sent for the initial machining. They are checked for
sand holes, discarded
if any, then final machining and checked again. Any
blocks or heads not up
to par are sent back to the foundry for remelt.
When blocks and heads
are found to be perfect, after machining, some are
destined for the
"premium" line. Generally for high performance, marine and
industrial use. From
what I have been told by some of the "old timers", is
that on the premium
engines, final machining is done with "new" tooling to
keep close tolerances.
"Used" tooling is the used on non premium blocks.
After all machining is
done, the blocks & heads are sent to the assembly
line. The 300 engines,
Pistons, bearings, crank, etc. are carefully
assembled. All of the
high perf. engines then get a precise balance job. I
have been told, plus or
minus 2 grams, other engines get as much as 20 gram
balance.
With the high
performance engines, they get a flame hardened forged
crankshaft to .060.
This is what makes a H.P. engine along with the
camshaft. N.Yers. and
Imps do not get these engines and their cranks are not
hardened. After the
precise machining, crank, camshaft, etc., then the "H P"
is stamped onto the
block along with the date of engine assembly.
All 413 blocks have the
same casting numbers along with the various shift
codes when they were
cast. Exception to that rule is the "motor home"
blocks. They are cast
special because of the extra cooling passages cast
into them and also the
heads. Motor home blocks and heads should never be
mixed with regular
engine components. But their cranks are hardened
Other non premium
blocks will have the "diamond", "maltese cross" and other
stampings associated
with "under sizes" incorporated into the blocks.
Re: undersize crank,
oversize rod bearings, oversize lifter bores, and
sometimes oversized
main bearing bores. On GM engines, one can find "shims"
under the main bearing
caps because of oversize line boring. Never will one
find these marks on a
premium "Chrysler" block.
All 413 blocks are not
the same. That goes for all the other "H.P."
engines that come out
of the Chrysler foundry and machine shops, 318, 340,
360,
etc.
In all of my years,
Chrysler builds the best engines.
George
Riehl>
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