Engine ID numbers will be stamped in to the block, they are not a raised casting number. If you open the hood on a Lumina APV, the engine is on the left and trans on the right, the ID stamping numbers will be in front of you on the back of the engine where the trans bolts to it, not on the firewall side. There should be 2 sets of numbers, one the date code and one the VIN derivative that ID's the vehicle it came out of. If you post these numbers I will try and ID it for you.
Posts: 400 From: waterloo, on, ca Registered: Sep 2002
The only differences between the 2.8 and 3.1 blocks is, well, actually, just about none. A 3.1 is just a 2.8 with a longer stroke crank and pistons with the pins moved up to account for the stroke. Both engines use the same connecting rod. There are trivial difference in the castings for stuff like a crank sensor and such, but for the most part they're the same engine. Functionally they're identical. Use the Fiero heads because they flow better. The Fiero cam is going to be more aggressive than the stock 3.1 cam I suspect.