from my understanding all sbc engines up until 1991 are 1st generation, correct? and from 1992 until 1996 are 2nd gen engines? so wouldn't it be easier to put say a 327 or 60's-70's 350 in my 91 rs than say a lt1? will the older sbc be a direct bolt in for my 91 camaro? if not, why? pretty much what i want to know is would an older sbc or a lt1 be an easier swap for my lo3 equipped camaro? thanks alot

 

As I understand it (and I'm happy to be corrected if wrong), the "bolting in" part is generally not an issue. In the Chevy world, anything bolts to anything. You can bolt in an LS7 if you've got the $14k to buy one. I once bolted up a "Rock Crusher" 4-speed to a stock '75 Vega 4-cylinder with zero adaptations needed on either end

The differences that are important to swaps between V8 generations are all in the heads and induction, and most often in bolting an intake to the heads. I think (and this is where I could be very mistaken), you can even put most any generation head on any generation block (allowing for valve interference, of course). LS7 stuff could be a big exception here. Of course, the injection/ignition/computer systems are a lot different from generation to generation.

Engine mounts and transmission bolt-ups are basically unchanged. If you're keeping all the engine's components together as a package, they'll bolt into your car just fine.

For first-to-first generation swaps, the primary concern is that 383's, 400's, and big blocks are usually externally balanced, so you can't use your stock balancer/flywheel/flexplate/starter combination.

 

There were a lot of little changes over the years. Accessory bolt holes on the ends of the heads, which side the dipstick is on, one- or two-piece rear main seal, flat tappet or roller lifters, angle of the center two intake mount bolts on each side, perimeter bolt or center bolt valve covers, etc. Get any of the "wrong" combo, and it can be a hassle to put it in a '91 (depending upon what all you do, of course).

Generally speaking, SBC's were Gen I until the Gen II LT1s, which came out in Vettes in 1992 - reverse cooling and direct-drive distributer were the distinctives of Gen II. However, the truck Vortec engine, which came out in 1996, is more Gen I than Gen II. The LSx engines are Gen III, and while they share the bell housing pattern (mostly), they are really completely different in all other aspects.

3rd gen f-bodies only had Gen I SBCs, although a couple of the changes in the first paragraph occurred during the run.

 

If you're considering a (high performance) engine swap and want to retain the TBI fuel system, check out the TBI forum. Otherwise, if emmissions are not a concern and you are thinking about a carb'ed motor or other FI system, check out the tech and swap sections on the board. Just depends on what you want motor wise in the bay. The II and III gen motor swaps are popular as well as the I gen build's. All have different requirements. So, before you decide do a lot of home work before you begin replacement of the 305.

Good luck