[Elarson]

Here's a few bits of info about the balancer fit and how it affects the crank nose. As usual, there are no black and white answers. It's all about managing your own set of risks.

When you tighten the balancer bolt, the balancer hub is in compression and the crank nose is in tension.

When you apply side loads from belts (either accessories or a blower) they try to create a bending moment. If the balancer hub is still in full contact with the crank face, the hub face reacts all of the bending load and the crank nose does not have any bending stress. But if the side load exceeds the preload on the balancer hub and the hub starts to lift off, then all of the bending is taken by the crank nose. Since the crank is spinning, the bending stress continuously orbits around and the nose quickly fatigues.

The fit of the balancer on the crank nose is especially important if there are side loads from belts. If there is radial clearance, the belt loads can cause the balancer hub to slide around, fretting the face against the crank and resulting in a loss of the bolt preload. Although there is considerable friction on this face due to bolt preload, friction becomes less reliable in the presence of vibration and heat.

So boiling all this down to a few rules of thumb:
The joint is more reliable if there is no clearance on the radial fit.
Belt side loads aggravate the problems with this joint.
Bolt preload needs to be higher if there are belt side loads. I suspect the factory engineers were worried about people tightening accessories with a 4 foot bar.

So if your race engine doesn't have belt driven accessories, you've reduced the abuse on the crank nose. But....belt driven stuff helps to dampen harmonics. That's how blower drives can work without a "balancer".

So manage your risks and go racing!

Eric