E: Engine Crankshaft Balance Method

[Vincent Brake]

Lot of reading,.
But heres what i do.
I have them in more vinnies at 51-54 percent.
Of your calculated weight.
I do take of weight by drilling up the 3 holes on top , do not ever

put tungsten or lead.... On the counterweight its already as heavey as it is .....
Even when i have to take more weight i just mill between the holes on the outside.

Cheers

Vincent

 

[Bill Thomas]

So how do you do the maths Vincent. Bill

 

[vibrac]

Here is the crank from our Big Bore Egli Racer I believe it was 45% Roy Robertson would know for certain

 

[Bill Thomas]

There you are Dave, You don't need a drill, Just a hacksaw. Only Joking Bill.

 

[Vincent Brake]

So how do you do the maths Vincent. Bill

I learned it from The Man Himself
Mr P Irving.
From his book; speed
Or so.

I will write it up today evening make picture.
I done more this way and really like doing it.

Just let me an afternoon with the girls.


Cheers
Vinnie

 

[Bill Thomas]

Try and keep it simple, I missed a lot of school !, I didn't like it . Cheers Bill.

 

[Monkeypants]

I would take the easy route as mentioned by Bruce.
Those new Maughans cranks aren't too bad for price and they are dynamically balanced. Also less than 1 thou per side runout according to Maughans and those who have checked them.

 

[Vincent Brake]

Well here it is.
I ve put line numbers so one and sure an other can shoot holes in it.
Please do.

 

[Monkeypants]

In educating myself on balance factor I encountered three different versions for the temp. bob weight calculation. These varying formulas must contribute to the confusion around balance factor and the wild range of numbers claimed as ideal for a given engine.
The calculation used by Hines, the computerized dynamic balancer manufacturer, is simple and seems to be the most widely used.

The temporary bobweight should be made equal to( 100 % of the rod big end weights complete with bearings and collars)plus the desired balance factor x (the rod small ends + complete piston weights).

I hope this doesn't shoot any holes in Vincent Brake's post above, don't think it does?

 

[Vincent Brake]

Not at all mr Glenliman.

Before assembly i try to balance a flywheel on an knife edge
But i failed. Could not keep all my balls up....

Anyway dynamic balance ing is always the best.

We have to make dummy crankpins than, as not to spoil the interference fit.
But nice to do once.