Quote:
Originally Posted by Jerry Clayton
There are two types of engines which require two different types of cranks--the inline engines and the "V" engines---With the inline engines they don't require the bobweights to be on them for spinning during balancing--
The V types require that bobweights be attached to the rod throws for spinning during the balancing process--The bobweights are made up of 100% of the rotational weight and 50% of the recipricating weight of 2 cylinders ( V8)--since the front two rod throws(4 cylinders) are at 90* to each other as are the back 2 rod throws also 90* while the two center rod throws( OK, so I'm up to 6 rod throws ?) are 180* to each other, the V8 cranks will have counter weights to the front and back but generally not at the center throws---( unless it has been CENTER COUNTER WEIGHTED for strength )
SOOOOOOOO---the addition/subtraction of weight for balancing is generally done on the first and last counterweight---
The 28 and 50 OZ numbers relate to inch/ounces--thats why the flywheel on the external jobs have less correction than the front dampners---differance between something 6-8 inch dia and 12-14 inches flywheel
The pics that I posted that show the imbalance(when I took the pictures) relate to grams. at the time the crank was at 2 grams on a 3 inch radius---
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Thanks Jerry. My experience up until recently has been with inline four and six cylinder engines. I couldn’t work out why you would add 28oz (or getting close to a kilogram) to the front and rear ends of the crank – in order to balance it!!
Cheers,
Glen