<VV> Rod caps and balancing

[Eric Aos]

I don't buy that. Think of a two cylinder opposed engine, the big ends go around together. The small ends going back and forth are going the same direction, so they are not canceling each other, they are helping each other. What keeps it balanced are the pairs of cylinders canceling each other out.
  The total of 1&2 needs to equal the total of 3&4 which needs to equal the total of 5&6.  The counterweights are the two other pair. Big end & small end/piston. That way as two pistons are going to the left at full speed, 4 are going to the right at reduced speed (one of each pair is leaving BDC, and the other is leaving TDC).
   
  Long story short... balance ALL rods & pistons.
   
  Eric

    <Snip>
   The way a 'Vair engine is put together is pretty much tantamount to three 2-cylinder engines sharing a common crankshaft. The opposing pairs of rods/pistons simply don't interact with other opposing pairs... unless something is VERY MUCH different as regards weight and even then it's not gonna amount to THAT much vibration. 

This is why a 'Vair crank gets away with having no counterweights. 
<Snip>