Standard Weight of a 440 Piston & Wrist Pin?

[69Bee]

I think maybe my question was worded wrongly and being misunderstood. I was speaking of engine builders over or under balancing to match a more specific rpm. I really don’t care what balance is at idle a street engine spends most of its time in 2500-3000 range. And race engine maybe more like 4500-8000 build and use dictating. I was just saying if the different weight piston falls within that +\- 2% of bob weight. What would it hurt to use? Just looking at some simple stuff found on line .02x2500g=50g. It seems as if stock dod weight is around 2500-3000g depending on con rod and piston. So 50g different piston/pin weight falls within 2% of neutral balance weight.
I have no intention of using a piston/pin combo 200g lighter than factory without rebalancing. But 50g? Let it rip!

Here is a paragraph from my book I showed you.

"With OEM's accepting 2.0 oz/in, with a 6" diameter crankshaft, it would have potentially 18.95g of unbalance weight residually embedded at the outside edge of the crankshaft counterweights. Running this imbalance at 1000 RPM will cause the rotating assy generate a centrifugal unbalance force of 3.56lbs. As the RPM is increased to 2000 RPM, the force increases to 14.25lbs and at 4000 RPM, it increases to 56.5lbs of imbalance force. At 8000 RPM, it becomes 228lbs of imbalance force."

Now, 50g is 2.634 times heavier, so just hypothetically (not that it would be linear of course, but let us indulge):
1000 RPM = 9.38lbs of unbalance force
2000 RPM = 37.53lbs of unbalance force
4000 RPM = 148.45lbs of unbalance force
8000 RPM = 600.55lbs of unbalance force

I hope you don't have any fillings in your mouth...

 

[68-500]

I couldn’t read your pics on my phone. I understand stand what you’re saying. I believe you’re speaking of a pure mechanical balance. Im speaking more dynamic balancing with combustion pressures and everything else that goes on in a running engine. As stated above its more art than science. Whats good at 1000rpm is different that 3000rpm different than 6000. When you’re talking a running engine. A 800g piston slowing nearing tdc @6000 rpm is a different force than the same piston slowing nearing tdc@1000 rpm.