RE: Internal vs. External Balance

From: Ray Block (
Date: Sun Feb 28 2010 - 13:57:56 EST

> -----Original Message-----
> From: Gary Hedlin
> I'm not absolutely 100% on it, but I thought I read somewhere that
> the 318's and 360's were internally balanced and the 340 was
> externally. But maybe it's a year thing since mine was a 72 with the
> cast crank and 318 rods.

Gary, it can be found on the web but the 273/318/340 engines shared the same
stroke. The cranks and rods are the same dimensions although I've read the
340 parts were somewhat sturdier. I can't confirm there was any difference.
The early (60's-70's) engines used forged cranks. Later ones may have used
cast cranks. (Ma Mopar cost savings ya know) Since my magnum 318 is
internally balanced I'd have to think that at least all 318's have always
been that way.

The 360 arrived on the scene in 1971 and it's crank uses larger mains than
the other engines but the same rods. 360's have always come from the
factory with cast cranks. By my experience and study, the 360 is the only
Mopar small block to be externally balanced from the factory...but I don't
claim to know everything about individual model year engines I haven't
owned. ;)


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