3.1 L Engine Block ????

[FlyNLoIMCA17]

I have a 3.1 L engine that I am going to be building soon. The other day I was looking at it and noticed that the block had a ribbed type construction on the outside of the block. I read on a website that the 3.4 was the one with this type block and that the 3.1 had a smooth block like the 2.8. This engine was removed from a Cutlass I think. My dad had removed it a few years ago from a customer's car. He said that he thought it was a 93 model or so. But he wasn't sure. The upper intake manifold said 3.1 MPFI. I haven't torn it down yet to see if it is actually a 3.1 or not. But does anyone know about the ribbed blocks?? I got what little info I know about them from this website http://users.spec.net/home/emxjc/block.html

Thanks!

[GutlessSupreme]

If the manifold says MPFI, then it can only possibly be a 2.8 or 3.1. No one would go through the trouble of trying to install it on a 3400, and they're just not close to compatible with the 3.4 DOHC. I dunno anything about ribbed blocks though. pretty sure none of my 3.1s are.