We figure that you could actually build about 120 hypothetical small-block combinations by substituting a bore size other than the 0.030 overbore we used here. However, a few cardinal rules control what you must consider when planning these engines in your mind or on paper. Not all of them may work exactly as planned. That's mainly due to the bore size of some being too small to work with the long strokes of others. There's a general rule of thumb for engine building that's not to go "over-square" with your bore-stroke combination. What this means is that you should not have a tiny bore with a long stroke. Ideally, your bore dimension will always be bigger than your stroke, as in the original 4.00-bore/3.48-stroke small-block that we know works so well. If you were to drop a 3.75 crank into the tiniest 3.500-bore small-block, you'd be building an engine with the high-performance equivalent of Asthma. That's because small-bores don't allow much breathing room around the valves. In fact, most small-bore engines have to use smaller valves just to make sure they don't hit the block at max lift. This is perhaps one of the reasons the not-so-well-thought-of 307 never made it to hot rod heaven. It had the long stroke of a 327, but the small bore size. Small-bores are also the reason why the 305 has never made any real power. Basically, when you're idealizing your next project, try to swap the short-stroke cranks into the big-bore blocks.
For those of you craving something truly unique that will last just as long as anything else on a budget, dive into one of our evolutionary small-blocks.
Some of the BestAs we mentioned, you could theoretically build more than 120 different small-blocks using stock bottom-end parts, not even counting all the de-stroked combinations you could make with the factory 400-block. There were four different-stroke small-block cranks offered by GM that, at one time or another, all had 2.45-inch mains and 2.100-inch rod journals. But not every block was machined to fit 2.45-inch mains. The 283, for example, only came with 2.30-inch mains. But, you can always turn down the mains of the larger cranks to fit the journals of the smaller blocks. The '62-and-later 283 blocks had enough clearance on the bottom of the cylinders to accept a 3.25-stroke 327 crank. Bored 0.030-over that makes for an easy 311 cid. Common reasoning would follow that the earlier versions of the 283 blocks would also work for this stroker swap. However, 283s cast before 1962 can't fit a 3.25-stroke crank.
Evolution of a GiantWe looked at all of the possible combinations and determined, theoretically, the 10 that might work best. Considering the availability of aftermarket pistons, the feasibility of making almost any of these combinations work on the street is very real. Also given that there are so many affordable aftermarket stroker cranks available with 2.45-inch mains, we can't ignore using them in these calculations. However, as we explained earlier, you wouldn't want to go too far by dropping a 3.75 stroke into the tiniest bore block because it won't really do you much good. We prefer the more common 3.48-crank swap into other blocks because it's the easiest part to find cheap in the junkyards. We won't get into the more common swaps like putting a 350, crank in a 327 block because that would just make it a 350 and that's not very unique.