Reference Equaliser Pulley

[Hazel]

The big heavy one that's supposed to balance the engine out. 

If I'm going to have it balanced with the crank rods and fly wheel, would it be best to have the 2 wholes on either side filled before hand? Surely these holes will throw it out of balance - or is there a reason for them? 

[Mantaray]

Hi Hazel,

When I had mine dynamically balanced I assembled the whole bottom end then gave it to they guy to balance.

Worth remembering to put distributor drive gear as well. Here is photo of mine when it came back.

[Mantaray]

Sorry you asked a question the two holes are for getting the pulley off and will not affect balancing if all done together.

[BEELZEDUB]

Hazel, as Mantaray said, those holes are for pulley removal, on the back of the equaliser pulley you may see dimples/drill spots where the pulley was balanced at the factory, it will still need to be assembled with the whole crank etc for the dynamic balancing.

[Peter]

Just to add to this, and hopefully alleviate Hazel's concerns. When the bottom end
is balanced it should/willo be assembled and be marked in places to help
when it is taken apart and rebuilt later.

Any imbalance due to holes or misalignment will be taken into account and remedied when the assembly is
balanced.

So there's no need to do anything to these holes and as Beelzedub rightly points out, many of things are balanced at the factory, and this just
helps the whole process along...

Peter

 

[Hazel]

There are no dimples

And, I've since been in touch with 2 different companies that do engine balancing, and they both confirm that the holes will cancel each other out. 

[Hazel]

Just to add to this, and hopefully alleviate Hazel's concerns. When the bottom end
is balanced it should/willo be assembled and be marked in places to help
when it is taken apart and rebuilt later.

Any imbalance due to holes or misalignment will be taken into account and remedied when the assembly is
balanced.

So there's no need to do anything to these holes and as Beelzedub rightly points out, many of things are balanced at the factory, and this just
helps the whole process along...

Peter

 

Marked in places  you know what happened last time, with the flywheel/crank...

[Peter]

Hazel 

Yes the holes will cancel each other out, do you know why ?

If an assembly has features that are uniform and evenly distributed, ie holes then all will be ok.

The real concerns are the bits that are uneven on the assembly and will throw things out, ie the crank journals..

Pulleys are round and a pattern of holes on the same PCD (Pitch Circle Diameter) will spin without problems, its the mass of the bits
that fling in and out and set up shock loads that are the real culprits.

Peter

[Hazel]

Hazel 

Yes the holes will cancel each other out, do you know why ?

PHYSICS! Everything is physics! 

Thanks for the guidance 

[Peter]

Well, I was just trying to fill in the gaps, its not too bad a subject really....

Not physics in my head, just stuff whirling around in a crankcase, some of its balanced, some isn't.....

 

[BEELZEDUB]

There are no dimples

And, I've since been in touch with 2 different companies that do engine balancing, and they both confirm that the holes will cancel each other out. 

i have a Gene Berg equalizer pulley and mine has factory dimples in the back, i figured that due to the nature of the equalizer pulley that they would be weighted and balanced from stock.

[Peter]

Yep,

Thats the thing to remember, many bits are balanced in their own right by
the manufacturers, however when its all bolted together as one unit, crank flywheel etc etc...

It all then has to be balanced as a whole!

Peter