Those dowel pins on the flywheel.
 

I was looking at this; and I wondered ; Why are those dowels so short.
It would seem like they should be long enough to "fill" the flywheel and
the crank . you know maybe another 3 mm in length. Does anyone make
longer ones. and are there Oversize ones ?
TIA
--
Karma, What a concept!

Those dowel pins on the flywheel.
 

On 1/30/2012 1:21 PM, Mr. K wrote:
> I was looking at this; and I wondered ; Why are those dowels so short.
> It would seem like they should be long enough to "fill" the flywheel and
> the crank . you know maybe another 3 mm in length. Does anyone make
> longer ones. and are there Oversize ones ?
> TIA


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
"off" position.

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.


Jan

Those dowel pins on the flywheel.
 

On Tuesday, January 31, 2012 7:58:42 PM UTC-5, Jan Andersson wrote:
> On 1/30/2012 1:21 PM, Mr. K wrote:
> > I was looking at this; and I wondered ; Why are those dowels so short.
> > It would seem like they should be long enough to "fill" the flywheel and
> > the crank . you know maybe another 3 mm in length. Does anyone make
> > longer ones. and are there Oversize ones ?
> > TIA
>
>
> 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
> "off" position.
>
> 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.
>
>
> Jan

Every 8-pin flywheel and crank that I have, all the pins are the same

Jim

Those dowel pins on the flywheel.
 

On Jan 31, 5:58*pm, Jan Andersson >
wrote:
> On 1/30/2012 1:21 PM, Mr. K wrote:
>
> > I was looking at this; and I wondered ; Why are those dowels so short.
> > It would seem like they should be long enough to "fill" the flywheel and
> > the crank . you know maybe another 3 mm in length. Does anyone make
> > longer ones. and are there Oversize ones ?
> > TIA
>
> 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
> "off" position.
>
> 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.
>
> Jan

Wedgemating is still pretty commonplace on drag racing engines, in
particular.