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This is one of our projects which is still in development. Some crankshaft types (not all) require dynamic balancing to be carried out with simulated rod/piston masses attached to the rod journals. The complete project will assist crankshaft balancers with the computation of bobweight masses and also in the removal of material, or the addition of tungsten/Steel alloy (Mallory metal or 'heavy metal') in the actual balancing phase. The program available here is the first part of that project, in that it helps to compute the bobweight masses.

A 'perfect' crankshaft balancing job, where bobweights are to be used, will have the balancer weight matching all the pistons, all the rod small ends and all the rod big ends. This way any rod can be coupled with any piston and all the bobweights will be equal. However, this is not always necessary unless you are building an all out, high RPM, highly stressed racing engine. For the most part, street driven (and to a great degree some race engines) can be balanced without matching all the individual components. This can be achieved by combining the rods and pistons in such a way that makes the bobweights on each journal become equal (or very close to equal).

This program takes all the individual weights of the big ends, small ends and pistons and the weights of the other components (rings, bearings, pin locks, oil allowance) and produces a list of which piston should go with which conrod to give the closest tolerance on bobweight mass. The bobweight mass is also specified. Two sets of results are shown, one is the 'optimal' solution which may require re-numbering the conrods, the other is for keeping the conrods in the correct cylinder number.

Some points to note:

  • This method is of most use for balancing engine assemblies where pistons are bought as a set and the conrods are bought as a set - ie they should be fairly closely matched to begin with (within a few grams).
  • This method should not be used to balance engine assemblies with 'odd' pistons or conrods from a set - bring the 'odd' one down to a similar weight to the others.
  • At present this program does not take into account left and right handed pistons (ie Small Block Chevy). Care should be taken to ensure the correct piston is fitted to the correct cylinder.
  • The cylinder numbering system on this program is the same as that used on Chevrolet and Chrysler engines. ie: 1+2 are frontmost cylinders, 7+8 are rearmost. Future revisions of the program will allow for other numbering systems.

    This program is available for Free download by clicking the button below. However, when the project is completed (with the other additional features) there will be a charge payable.