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Re: engine balance

To: "Glen Byrns" <grbyrns@ucdavis.edu> information
Subject: Re: engine balance
Date: Fri, 10 Jun 2005 20:01:21 -0400
Cc: <spridgets@autox.team.net>
References: <000e01c56e11$e9e14080$6664640a@vgl.cvg.ucdavis.edu>
Glen,

I am no expert on this stuff, but I have to say YES, you are getting  
hosed. Seems to me you need the rods and the pistons, rings etc to  
balance the engine. I think you also need the crank. And perhaps the  
flywheel. I know when I had this done on a now broke motor, they  
wanted everything. Broke for an entirely different reason.

I can see why the rods would be different. The object, as I  
understand it, is to get all the throw weights the same. And I do  
believe that includes the counter-balances formed into the crank.

I could be a crank on this, but I don't think so.

Larry

On Jun 10, 2005, at 7:12 PM, Glen Byrns wrote:

> Is there anyone on the list with knowledge of correct technique for  
> dynamic
> balancing of internal engine parts?
>
> I got back the crank, rods, pistons, flywheel, pressure plate, and  
> harmonic
> balancer for the 948 I'm building for the Austin A35.  They had  
> mixed up the
> #2 and #3 rod before balancing.  Since the #2 rod cannot be used in  
> the #3
> position, I called and asked what they needed to redo the balancing  
> with the
> rods in the correct positions and they replied that they only  
> needed the rods
> back.  This made me damn suspicious that they are full of crap.  I  
> took the
> rods to work and weighed them on an accurate balance with the  
> following
> results:
> #1-----644.0g
> #2-----647.5g
> #3-----657.5g
> #4-----661.0g
>
> There may be some reason that the rods can be of such different  
> weights and
> still have a dynamically balanced engine I guess, but I thought  
> step #1 was to
> match the weights of all the rods and pistons BEFORE the dynamic  
> balancing is
> begun.
>
> Am I getting hosed?
>
> Glen Byrns

-- 

Larry Macy
78 Midget

Keep your top down and your chin up.

Larry B. Macy, Ph.D.
macy@bbl.med.upenn.edu
System Manager/Administrator
Neuropsychiatry Section
Department of Psychiatry
University of Pennsylvania
3400 Spruce St. - 10 Gates
Philadelphia, PA 19104

The bottom line: Sure, there's pain in adopting the Mac. But if I  
accept that, I get to use a computer that works, and that pretty much  
does what I expect and want a computer to do.
Stewart Alsop, FORTUNE, Monday, June 25, 2001


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