Pete, you better rethink this. You better be more clear as to what you are telling us. What timing mark? How is this timing mark 180 out? Jerry is assuming you mean the balancer marks and pointer, and I would assume that also........... but I have learned that nothing can be assumed on an initial posters post.
NO, the balancer can not be put on wrong, it's keyed to the crank.
SO:
1. What motor?
2. What "timing marks"? Make sure you are not talking about home made marks or the distributor rotor or some other thing.
3. How are you interpreting 180 out?