Con-rod weight marks

[t_s]

I recently had reason to take the con-rods out of my "spares" R80/7, and noticed they have "-10" scribed on the sides. I've proviously seen pictures of rods with "-3" and "-4". AFAIK this is weight differences relative to a standard - but how much does one of those units equal to in grammes? One?

Considering the weight one one con-rod, one gramme equals to 0.175 % of its weight. At least the one I just weighed

 

[DrFarkoff]

As long as they are both the same weight give or take 5 grammes (I think that was the spec)

Why Worry?

 

[t_s]

Why Worry?

Good question. Reason is that I've acquired a lightened & balanced flywheel, and when installing this, I thought I'd check out & balance the reciprocating mass attached to the crankshaft. Light conrods would in itself be a good starting point, IWHT; but end-for-end balanced ones even better. Knowing how much the weight unit differences of the conrods are is part of the equation.