Stayed on the sidelines on this one as long as I could...
If your seaking obnoxious levels of ignorace ( read Very High RPM 0ver 7k)
then have it balanced by your local machine shop.... and the way they do
that is to take your pistons, rings and pin's and get a wieght... then they
do the same for the big and little end of the rods.... They do some fancy
Math and come up with a Bob Wieght for the Crank... and then with the Crank
on a Balancer they install this Bob wieght on the crank and spin her up....
then add or remove metal as appropriate to the crank.... if you want to do
it with your flywheel go ahead it won't hurt a thing.... except that Crank
and Flywheel must remain as a Pair for ever.... and since they are
internally balanced engines ( I think ) the flywheel should be Zero Balanced
out of the box....( less wear on the ring gear... and on many of mine that
is substantial ) so it really isn't nessesary....
But None of this is Nessesary if you maintain the engine as a set.... ( not
mixing heavy pistons with light ones ) I really don't know how this was
done at the factory.... but I have a sneaking suspicion that it was balanced
by design and never checked as a recipocating assembly.... in other words
they Balanced the Cranks as they were manufactured to a design specification
and after that the other parts were required to be a given wieght ..... or
at least that would be my thought... here in America that is how its
done.... to the best of my knowledge....
Bottom line if you love your car and want to keep the motor as Perfect as
you can.... and have more money then you need.... Hell go for it... it's not
going to run much better.... if at all... it's only MAYBE going to vibrate a
little less....and that is a Big Maybe... what your doing here is tightening
up those original specifications to make it more Perfect.... Works for
me....
Go ahead blast away.... Seriously I over balance all the race motors....
example... my bob weight is 1994 grams on the Rodeck 300 cubic inch motor
and the New Bryant Crank is balanced to 2000 grams.... this way I can
snatch a Piston or swap out a set and so long as they are within 5 grams of
the last set then they will be FINE.... and Yes it does set up a vibration
in the motor at a VERY low Rpm .... like 5K but it moves through that area
so rapidly that it's really not an issue.
Keith Turk ( you can see my junk at
http://downtown.ala.net/~kturk/camaro3001.htm )
----- Original Message -----
From <Daniel1312 at aol.com>
To: <toyman@digitex.net>; <spridgets@autox.team.net>
Sent: Wednesday, January 17, 2001 1:55 PM
Subject: Re: Piston Balancing
> You need to think British here. Most american vee 8s (excepting racing
> engines etc) don't really need to rev much over 5K. British 4 cyl engines
> are fine when stock up to about 6K. Its only when you start to push
> something like an A-series over 6.5K and certainly over 7K that you are
> 'running pretty high rpms'. The term 'high' is like any quantitive
> description, relative.
>
> As Frank and others have said it is the rotating stuff like the crank,
> flywheel and clutch that are well worth balancing. With rods the best
thing
> you can do is to have them bead blasted or lead peened (correct
> terminology??).
>
> Daniel1312
>
> In a message dated 16/01/01 16:33:17 Pacific Standard Time,
> toyman@digitex.net writes:
>
> << but an inline four is a slightly different principle but running pretty
> high RPM's >>
|