what are the real differences here? Im trying to build an L98 motor for my 88 camaro and Im having a HORRIBLE time trying to find a used L98 motor for anything near what im trying to pay for it. I will be replacing almost everything in there, so i dont want to pay a lot for a motor when I wont use most of the parts. So my question is, would it make the SLIGHTEST bit of difference if i just bought an old SBC block and bored it .030 over to 355 and then put a 2 piece rear main seal crank in there (as normal for that engine) and then just built the rest of the engine up using new rods, pistons, L98 heads and a Holley Stealthram Intake, which is designed for the L98 motor? (i mean i'd have to buy the harness, computer, injectors and all that, but all that stuff is easy to find. it's the motor in one whole piece that's giving me trouble).
are there any differences in the block's size or shape at all besides the rear seal??
thanks guys

 

You can bolt an earlier engine into an 87-up 3rd gen pretty easy. If you're going to use actual L-98 heads on top of the older block then your TPI system will bolt right on top of that. No intake bolt pattern differences like you would have to deal with for 86-down heads.

The only "gotcha" is that earlier 2-piece rear main engines used a different flywheel/flexplate than a later 1-piece rear main engine like an L-98. You'll have to buy an earlier style flexplate to go with the earlier style crank/block. Other than that it'll bolt right in.

 

The rear seal is different, the flywheel is different to accomodate it, and the oil dipstick is on the other side. This could cause a clearance problem with the exhaust but it shouldn't be too much of an issue. The lifter valley is different....the early-model block doesn't have the provisions for a roller cam so you'll have to run a flat-tappet or pay the big bucks for retro-fit roller lifters. The timing set is also slightly different to accomodate the cam.


It's also easier to find 4-bolt mains in the earlier blocks.


The heads/intake/accessories etc. are all fully interchangable. It's perfectly possible to take the heads and intake from an L98 and put them on an early-model 350 block. In fact, that's what I'm doing with the engine that I'm going to put in my Jeep.