What are the differences, if any, between the vortec 350 blocks and the older 350 blocks besides the 1-pc seal?

 

As far as i know they are completely different, as in the standard 5.7 block is Gen 1 smallblock and the vortec block is Gen III

 

There's no such thing as a Gen III Vortec 5.7

I think he's talking about the Gen II Vortec motors from the OBS trucks.

 

the cylinder heads for sure.

 

motor mounts on old 350's are close to the front of the motor, vortec's have em about in the middle of the block. I think exaust ports are in the same location on the heads.

 

OBS trucks had the GEN I engine not GEN II until 99/00 when Chevy released its GEN III for the trucks. The vortec 5.7L is a GEN I from 96-99. GEN II is the LT1 and LT4(reverse coolant flow). GEN III is LSx, LQ9, etc.

From 87-up, the GEN I blocks had a one piece rear main seal. There is no difference in the blocks on a 87-95 to 96-99 truck. The differences in the engines are heads, cam, and inductions. However, the 96-99 also has a crank/cam sensor where the 87-95 does not but doesn't matter on the block. The blocks are universal. I have the '880 block(96-99) truck in my 1990 at the moment and the '681(87-95) block on the engine stand waiting to be built so it can go back in the truck. No difference. However, if you have a 2 piece rear main seal then that would be the only difference in the blocks. Everything is universal and can match up for example, pre-86 heads with a pre-86 intake or 87-up heads with 87-up intake. And it will all go on the block.....just the rotating assembly will change b/c of the main seal design.

 

Actually its a GEN I the LT1/LT4 are GEN II's they differ mainly in their reverse-flow cooling system.

Some of the Vortec 350 blocks don't have the mechanical fuel pump pad drilled for the actuator rod. But basically the same, the motor mounts on the side are the same, heads have intake bolts that bolt striaght down, some other things.

 

Hmmm....well I was right about the first comment....lol

 

Unless you bored out a 5.3 to an LS1 then yes a Vortec 5.7 GEN III.

 

don't forget about the OPTI and the lack of mech. fuel pump. And I believe, not sure, but I think that SB 2.2(GM production block for NASCAR) is a tall deck GEN II block.