I recently sold a big block harmonic damper to a guy and was told it was no good as it had a hole drilled in the outer ring (similar to the attached image). My beleif was / is this was done at the factory and with as many examples as I have seen I never suspected it to be problematic. Am I wrong? I certainly don't want to dissapoint a buyer and you learn something new everyday so here I am asking. Appreciate your guys help!

Those holes look normal to me. I've never studied them, but I think all my stock balancers have them

I was a machinist for 10 years. I balanced a lot of engines. I drilled holes in the outer ring of the damper without any problems. You don't want to go super deep, tough. How deep is the hole?

For an accurate opinion you need to post a picture of the damper in question.

Unless yo're referring to a 400 or later 440 cast crank balancer

LINKY 1 FIXED LINK FYI 2nd one shown has pretty deep hole in outer ring

LINKY2

LINKY 3

Here ya go.

For what it's worth, the other five I have on the shelf are drilled as well. Come to think of it, I'm not sure I recall ever seeing one that wasn't drilled.

Send the buyer your photos and tell him to use a better informed machinist.

The last engine I had balanced came back with new balance holes drilled in the face of the outer ring.

The outer ring is not the best place to drill holes, it can and will spin after enough age and use
The hub is probably the best choice on balance drilling but what do I know

I let him know that it was typical and should be good to go. I told him if he wasn't comfortable using it though he was welcome to send it back and I would refund the purchase price. He says he ordered another one about the same time he bought mine and would compare them and decide from there. I can't imagine the other one is going to be any different but who knows. I can only do so much. Thanks for the input and support. I appreciate it.

the only thing i can think of, was this damper balanced to a certain crank at one point in time ?
if so, was it balanced to be neutral ? [used with any crank] or was the crank and damper balanced as an assembly ? the damper possibly be off, used on a different crank ?