What year is 330817 Chevy 400 engine?

There's no single year associated with a "330817 Chevy 400 engine" casting number. Chevrolet used a wide variety of casting numbers for their 400 cubic inch small-block engines over the years, and that number isn't one of the commonly referenced ones. To determine the year, you'll need to find the *complete* casting number (it's usually longer than that) and possibly other identifying marks on the engine block itself. This information can then be cross-referenced with engine casting number databases or Chevy engine identification guides to pinpoint the year of manufacture.