An external balance is an additional balance weight to augment the internal
counterweights which are part of the crankshaft. Steel crankshafts are heavier
than cast iron and generally don't require an external balance. Cast Iron cranks
on the other hand are significantly lighter and may not have the necessary mass
to provide the required counterweight for balance. A 318 has a smaller bore and
and stroke and shorter rod than a 360 so the reciprocating mass is less and
external weight is not required. If the 360 were made with a steel crank it
would probably be internal balance.
The 360 is a smaller bore (.040") long stroke 340, in fact the 71 and 72 360
blocks were cast using the 340 cores and can be safely overbored 0.100". It was
brought out in 71 for the large cars and was to replace the 383 2bbl which
disappeared the next year.
KW
T & J wrote:
> >From: Tim Roller<starwolf@bewellnet.com
> >Fri.10:00,20th
>
> >I'm the one who started this bru-ha about internal and external balancing
> and maybe I can help clear up a few myths. The old 318's from the late 60's
> thru the 90's, I have found them to have all been to be internally balanced.
> What this did for the cars or trucks these engines were installed in was
> give good fuel economy, but you had to bring on more RPM's to get top speed
> and torque. When the 360 came out, the Dodge Corp. it was externally
> balanced for a savings of time. That's not saying that the internals weren't
> balanced(just close enough). The harmonic balancer, flywheel,flexplate was
> the balance points for this engine. Along with larger intake and exhaust
> runners and a redesigned intake manafold with larger intake runners for
> lower RPM torque to move heavier weight vehicles with less RPM. Todays 318
> MAGNUM engines use a combination of both engines. They have the 360 style
> heads(highly modified)and big barrel intake for low end torque and
> internally balanced crank,rods,pistons,etc. for higher RPM's and long
> lasting life(as long as no overrevving is encountered). Of course when
> high-performance modifications are made,each mod effects another aspect of
> the engine. Such as exhaust,effecting gas flow,and changing
> air-cleaners(open element) affecting breathing ability,which in turn effects
> higher RPM's,better torque, but leaner conditions on top-end because the
> fuel-injectors weren't changed to higher flow models.
> Hope this helps between the two motors. I have run across some internally
> balanced 360's,340's, and other motors that were SUPPOSED to be externally
> balanced, but it was rare, and the steel vs cast type cranks may have made
> the difference.
>
> -----Original Message-----
> From: mike <moparman@indy.net>
> To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
> Date: Friday, February 20, 1998 4:13 AM
> Subject: Re: DML: 318 - 360 interchange; was Cat question
>
> >all mopars with forged steel crank are exterally balanced...all with
> >cast crank are internally balanced
> >
> >Klaus Wilkens wrote:
> >>
> >> JT,
> >> Nope, 360s (I don't know about Magnums) were external balance. Some of
> the later
> >> 440s and ones with 6 Pak rods were external balance but the older steel
> crank ones
> >> were internal balance as were Hemis, 383s, 361s, 413s 350s. Don't know
> 'bout the 400
> >> though.
> >>
> >> KW
> >>
> >> JT McBride wrote:
> >>
> >> > >All Magnum V8s use the same head and valve size.
> >> >
> >> > That's what I understand too - interchangeable heads, in fact.
> >> >
> >> > >Are youcertain the 5.9 Magnum is externally and the 5.2 is internally
> balanced
> >> >
> >> > I thought all small blocks were internally balanced, and the big blocks
> >> > (383, 440, etc.) were externally balanced.
> >> >
> >> > I'm no expert tho.
> >> >
> >> > Jim
> >> >
> >> >
> P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--
> >> > Dakota: The Right Caliber of Dodge Magnum Force!
> >>
> > -PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-PP-P--P-P
> P
> >> > 1993 Emerald Green V8 4x4 CC K&N, Accel Coil, Bilsteins, Redline
> synthetics.
> >> > Tread Lightly on Public and Private Lands -- Abuse it and we'll lose
> it!
> >
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