How much is my 1982 corvette stingray without original engine worth

Not knowing condition I would say around 20% less than a matching numbers car. If the engine is correct for the year and engine type your car had originally the discount might be less. There are a lot of other factors such as the originality/condition of the rest of the car. Even paint color should be original. I would do research on Haggerty and Hemming's Motor news as well as Corvette specialty sites to determine value.

If the car has no engine at all I would say maybe $5,000 if otherwise in good shape .

Older cars with true matching numbers are becoming extremely hard to find. That's why the trend now is to modernize the car and put in aftermarket parts, including a newer engine. My 69 Corvette had three major cracks in the short block after 325,000 miles, and it could not be fixed. I got a short block crate engine, put in my own desired parts, and now it purrs at 480+HP. On the outside it's stock, almost, interior is stock, looks stock but isn't. Good body and interior condition, runs strong and is not a junk looking work jobs having been done, it will bring between $15 to $25K. Like F-O-R said above, the cleaner it looks, the better the selling price. Remember in 82, if you were born yet, the parts did not last long, and were really being replaced. The only thing stock on my engine now is,...nothing.