Re: [Amc-list] 304 Flywheel balance - counterweight, or no counterweight?

["Armand Eshleman" <aje1@xxxxxxxxxxxxxxx>]

I have two 304s a 1970 and a 1979. 70 had auto now has manual, 79 had a SR-4
manual. The 79 flywheel is full of lightening holes and no added weight. The
70 flexplate had a few small added weld on weights. I have a 1970 360 with
auto. The flex plate has larger welded on weights. I searched for two years
for a 304 flywheel to put on my 70 304. When I found it I had it match
balanced to the flexplate that was on the engine. A little additional
material was removed from this flywheel to make it balance with my 304. It
worked great no vibration. The flywheel may really have been from a 360.  I
see two ways of external balance on 304s and 360s. Adding weight in a
strategic location or removing it. Correct me if I'm wrong, difference
between a 304 and a 360 is basically the cylinder bore diameter. Stroke is
the same, crank and rods are the same.  Pistons are different diameter.
Therefore I would guess that a 360 flywheel has less removed from the
strategic locations than a 304 flywheel. 390 and 401 flywheels have an added
boss on the engine side of the flywheel in addition to balancing by drilling
the outer circumference of the flywheel, just like the 304 and 360. ( I have
a 1970 390 flywheel too).  The reason the Jeep guys are saying there's no
vibration is because there really is very little that you can feel between a
mismatched 304 or 360 with incorrect 304 or 360 flywheels. Only the weight
of the little end of the rod (piston?) is different between the two (not
accounting for differences in weight in individual parts and pieces from one
to the next).
Almost forgot to mention I also have a flywheel for a 76 401. It has the
added boss just like the 390.
Sorry if I repeated myself on any of this in a prior post.
Armand


----- Original Message ----- 
From: "Jim Blair" <carnuck@xxxxxxxxxxx>
To: <amc-list@xxxxxxxxxxxx>
Sent: Tuesday, June 03, 2008 12:45 PM
Subject: Re: [Amc-list] 304 Flywheel balance - counterweight, or no
counterweight?


> The AMC V8s that I am familiar with (304, 360, 401) use a progressively
larger balance weight depending on the motor size. I haven't checked the 327
I have yet. If you pull a 360 and put in a 304, a minor grinding of the slot
on the flexplate will get it closer to balanced (some Jeep guys have done
the swap w/o changing the weight, but I can feel the vibes they say aren't
there)
>
>
> From: "Spro" <msproviero@xxxxxxxxxxx>
> Subject: [Amc-list] 304 Flywheel balance - counterweight
> To: "'AMC/Rambler owners, drivers and fans.'" <amc-list@xxxxxxxxxxxx>
> Message-ID: <000001c8aff2$c5731860$6401a8c0@deathstar>
> Content-Type: text/plain; charset="us-ascii"
>
> Everything I have read to date has indicated that 304's are balanced
externally neutral with no
> square counterweight cast into the flywheel, much like Armand mentioned in
his reply to the other
> post.
>
> Sounds like we have something to clear up...
>
>
> -Spro
>
>
>
>
>
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