I have what I believe is a '91 3.1, but someone who charged my AC insists it's a 2.8. The block number is A91097CD. I don't know where to find the casting number or I'd supply that.

Anyone?

Eric

2.8's wern't made in 91...

Take a look at the plenum... it'll say "2.8 MuliPort Injection" if it is a 2.8, if it's just plain, it's a 3.1... No need for block or casting numbers...

If all he's doing is charging your AC, what does it matter anyway?

Yeah, 2.8's weren't used past...89? A 3.1 is practically the same engine anyways, just added stroke.

The engines are so closely related he probably could not tell the difference.
But who knows. Maybe someone had an engine failure before you bought it, and stuck in a 2.8. But somehow I Find this HIGHLY unlikely.

Yeah, I'm under the impression that all 2.8's said 2.8 on them...

To my knowledge, they do... I've never seen one that doesnt.

Only if the upper plenium was changed. But IMO that is a 91 casting #, and their for it should be a 3.1l, unless it has had a 3.4l kit installed

Open your DRIVER DOOR.
Look at the printed sticker door tag.
There is the DATE of MANUFACTURE of your car.
Hopefully this is NOT painted over.
I'll bet your car was made
Jan/Feb 1991.
Second clue
Look at driver mirror
See a code etched on mirror glass?
I'll bet it says
0-DMI-(#10, #11 or #12)
IF these clues are "kinda" correct, you have original engine.
1991 had a 3.1 mill in them.
CLUE for a 3.4 mill?
EASY
Look at TOP of engine, RIGHT IN FRONT OF THE INTAKE MANIFOLD SEAL AREA?
IF you have a plug with wires coming outta there, you have a 3.4 block.
That is a sensor for reading the CAM for the DIS ignition systme signal for the 1993-1995 3.4 engines used in RWD.
ONLY 3.4 blocks have that.
Since I don't deal in 3.4 mills for FWD, I do not know if this is also correct for a 3.4 FWD block.

DMI= Donnely Mirror Inc.
DIS= DistributorLESS Igntion System