I currently have hardwood flooring installed originally in this house which was built in 1946. I want to install engineered flooring on top of the current hardwood, is this acceptable??

If you do it should be installed the opposite direction of existing flooring. Also you will need to check the height of new floor at doors appliances and other areas were it may be an issue. Is the existing flooring to bad to refinish as it would be a better option if possible?

Why go over it? If its that old it should be an easy demo, probably loose. Then just install some new solid wood. No issues like Mickey pointed out. Or nail down some new solid over it. Your floor is only as good as the floor or subfloor under it.

Thanks fellows for the info.
The problem is the floor is in very bad shape, has been screwed down in places, cut out in places and replaced with plywood, also another issue is the hallway, and the bedrooms have vinyl tile over the hardwood, and I have been told that they contain asbestos, and don't want to take them up. Planned on nailing the floor down just wasn't sure if I could.

Without seeing the floor it's hard to tell, but from your description, I might consider sheeting over the top with 3/8" CDX plywood. Also would need to consider height.