What if any are the internal differences between a "vortec" L31 short block and a L98 short block? I have found both for the same price and was just wondering if there is any advantage of one over the other?

 

87 and up L98 block should be nearly identical to the vortec blocks. There are a few differences on the vortecs however.

The timing chain area on the vortec uses the plastic cover compared to the L98 sheet metal one. The plastic one uses a different bolt pattern but some vortec blocks are known to have both sets of holes.

Also the hole for the mechanical fuel pump rod is not drilled out on a vortec block. So if you plan on using a mechanical pump do not get the vortec.

The only other thing I can think of is some vortec blocks came with 4 bolt mains but really there is no advantage to 4 bolt blocks in car applications. 4 bolt blocks are meant for the large trucks which can see very high cylinder pressures.

I think I said vortec too many times...

 

Ok, Thanks for the info. I'm not going to be using a mech. fuel pump. I'm just looking to buy a short block because I want to build a new engine for my 91 Z but I dont have time or room to completly rebuld one. So I planned on buying a short block then putting my LT4 Hotcam in it and aftermarket heads with a HSR and swapping everything I need from the engine in my car and then pull one and install the other. So that way i'm not taking up space for to much time.
But thanks again for the block info. I guess I'll just buy the L98 block since I already have the L98 timing cover.

 

I mis read your post. For some reason I didn't read short block I just read block. The vortec has slightly better internals. They have slightly lighter pistons and also have powdered metal rods which are a bit stronger. I would probably go for the vortec block.

Also a new plastic timing cover with bolts and build in gasket is like $25 from summit.

 

Now thats what I was wondering. Thanks for that. I figured there had to be some difference between the 2 internaly. But it sounds like the vortec is better so I'll take your advice and go for the vortec.