Re: [ihc] SV engine balance

[bearbvd@xxxxxxxxxxxxxx (Greg Hermann)]

At 3:59 PM 9/24/03, J Grammer wrote:
>>Flywheels are all the same--except for the four cylinders, which are
>>neutral balanced. The balance differences (266/304, and 345/392 are taken
>>care of in the crank counterweights.
>>
>>Greg
>
>Greg, does this mean that the SV motors are *both* 'internally' and
>'externally' balanced? This is something I've suspected every time the
>question comes up. After all, we know the flywheels interchange amongst the
>V-8's, and they are obviously counterweighted(as is the 'damper' on the
>front of the crank). What's doing what in this system?
>
>Thanks,
>
>Jim

Ain't semantics a wonderful thing, Jim ??

In my world--when an engine (talking V-8's only, here) has ANY bob weight
on or behind the flywheel/flexplate and/or the front pulley--it IS
externally balanced. YES, of course, there is internal bob weight balance
included on ANY externally balanced V-8, at least that I know of.

On a V-8--some of the counterweights on the crank are for the purpose of
reducing bending stress in the crank and block by providing mass adjacent
to the big end mass of the crank pins and con-rods. Other of the weights on
the crank (notice how they get bigger toward the ends!) are for providing
'bob-weight'--to balance out the forces generated by the motion of the
pistons and small end mass of the con-rods in a V-8 with a 900 crank.

Ideally--a V-8 would have an EIGHT weight crank--with a weight to counter
the big end mass as near as possible to each of the big ends--AND the two
bob weights CENTERED on either side of the #1 and #5 mains--meaning--half
of each needed bob weight to the INSIDE of said mains, and the other half
EXTERNAL to said mains--thus minimizing the bending on the crank due to the
action of the bob-weights.

Another hot-rodder/magazine myth/urban legend EXPOSED/DEBUNKED !! This one
is right on up there with 'stainless' valves !!

A V-8 with entirely internal balance/bob weights puts MORE bending stress
on the crank than one, such as an IH SV which has a moderate amount
(roughly 1/2 the needed bob weight) placed EXTERNALLY at each end of the
motor !!

If you doubt this, check out the number of small block Chubbys that break
their crank at the flank of the front counterweight due to the bending
stress that results fromall of the bob weight on them being internal !!

As usual, IH did it the RIGHT way !!

Greg