Just me tossing out ideas here... This isnt the first I've seen in terms of web stuff of that particular break. I have a couple of these in service in the 460-480 level (and automatics) and I will admit I'm nervous enough to probably stop sourcing them. But it terms of the "whys"... It looks like it started at the fillet which "should" be a fairly strong area. But that's where the otrsional stress is and the rpm doesnt matter if the harmonis are bad for wahtever reason. External balancing lends itself to stressing the crank more forcing it to flex, and a loose balancer or one that was hammered on or honed to fit more loosely can all contribute to crank stress, as can detonation. Never mind the 4sp part.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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