R975 help

[45jim]

Perry, I'll have to check the manual (I think I lent it to you in the past) on the radial to see if there's anything unique there, but the balance for all reciprocating engines is a basic two-step process. Individual components are "statically" balanced and then the assembly is "dynamically" balanced.

I can't help feeling you already know more than I here, but a flywheel is almost always located by keyway, dowel, bolt pattern or splines so that it indexes in only one position. Low rpm engines may be exempt from this, however.

Most production engines are not dynamically balanced and merely assembled from parts that have been statically balanced and/or sorted by weight so that the engine builder can select parts to achieve a "close enough" balance. I can't say that applies to aircraft engines, I just have no experience there except with the RR meteor.

As an aside, I wonder who would be able to balance a crank like that in London, the bob weight to replace all those pistons, pins and rods would be significant and it would have to be spaced out equal to the stroke, not the type of parts you see in your local engine shop used to balancing short stroke V8's.

The only item I think you would have to be cautious of is the pressure plate, these are often not indexed and the machinist would have to mark this alignment for you after balancing.

Really I'm surprised your not doing it yourself with an electric drill, some chewing gum and a dial gauge suspended from the tailgate of your pickup. I am always amazed with what you accomplish in that garage of yours.