Re: [AMC-list] AMC factory engine balance

[Frank Swygert <farna@xxxxxxx>]

Todd, that was for the V-8s. It was similar to a wheel balancer only is spun up the crank in an assembled short block. It's possible that the sixes were done the same way. My understanding is that was for "fine tuning" and when the balancer was drilled. 

For factory assembly, it stands to reason that you cast the pistons and rods, weigh it all, then cast the crank to something close. I don't know what the "close" standards were though. I know the standard for balancing an engine after the fact (a shop doing it) is +/- 1 gram for a piston/ring/pin assembly, and for each end of the rod. That's 2 grams leeway from lightest to heaviest. I did a "minor balance" on the last 196 I built (didn't do it on my stroker though) but don't recall the differences in the weights of anything. I had to remove very little from a few pieces to get them all within 2 grams -- just a few hits on the bench grinder for a couple rod ends as far as I recall. I believe the piston assemblies were all within the 2 gram range and I didn't touch them. Modern casting/machining is very good! I'd say "modern" being from around 1960 up. You have to almost go to pre-war stuff to find really rough castings that vary more than 4-5 grams in weight. Even some of the 
old Mexican cast pistons I've seen were a bit thick and crude looking on the inside, but they were still within a few grams of each other. Maybe the poured the metal in by weight though...

-------------
Date: Fri, 19 Feb 2010 08:32:18 -0600
From: Todd Tomason <jayscore@xxxxxxxxxxxxx>

I recall reading an article that AMC used a balancing machine of some sort 
in their engine factory.  Of course now I can't find it.  I'll keep looking.


--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
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