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- Those dowel pins on the flywheel.
January 30, 2012, 1:21 pm
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Re: Those dowel pins on the flywheel.
Well, you don't want them dowels to be so long that the bolt/washer
starts riding on the pins instead of clamping down the flywheel.
I believe there are oversize pins and also smaller diameter pins.
A very common trick is to install an additional 4 pins, for a total of 8
pins. Called 8-pinning. I seem to remember the extra 4 pins are smaller
diameter so the crank end would not look entirely like swiss cheese.
They are drilled at a non-symmetrical pattern, so the flywheel, once
drilled in the same pattern, would then only fit on the crank one way.
Once balanced, it will stay balanced because it cannot be installed
8-pinning is enough for most high performance engines.
One more trick beyond that is wedgemating. That means the mating
surfaces are reworked to a wedge shape, and the tighter you run the
bolt, the tighter the wedge shape grabs and holds the flywheel to the
crank. It was popular on some high $$$$$ builds years ago, not sure if
it was a fad or still around. 99% of builds will be just fine with
8-pinning and it's much cheaper.