GM offered four different-stroke...
GM offered four different-stroke cranks with the large main and rod journals needed to make these swaps work. Almost all small-blocks were offered at one time or another with the 2.45/2.100 journals, except for the 283 and 400s.
We've listed all the blocks as if they've already been bored 0.030-inch over. We also added the letter "L" to any of the blocks or cranks that were later offered with the 2.45 mains and 2.100 rod journals. We've also included the calculated compression height of the pistons given a 0.010-inch deck clearance and using 5.7-inch connecting rods. Any of these swaps, particularly the de-strokers, are wide open for using longer connecting rods. It's been proven by just about every professional engine builder in the world that longer rods help power. And since there are now so many affordable aftermarket rods available and getting pistons made with varying compression heights is a no-brainer, there's really no reason not to long-rod it. If you're planning to build one of these de-strokers, then talk to your piston manufacturer and get his input on longer rods for a better rod/stroke ratio and more power.
The 254-cid DE-Stroker3.530-Inch Bore 267 Block 307/327l 3.25-Inch Crank1.690 CHThis is the first of our hypothetical de-strokers, and it'll rev like an angry rattlesnake! Anytime you de-stroke an engine, you're effectively increasing its bore size relative to its stroke at the same time. That makes a quicker revving, better breathing engine capable of more power in its upper-rpm ranges. Since the '79-81 267 came stock with too much stroke anyway-it had a practically symmetrical 3.50 bore and 3.48 stroke-you could build a better combination by using a factory 307 crank because it'll drop right in, but you could also use a '68-69 327 crank.
The 267/276-Cid Screamer3.766-Inch Bore 305 Block 262/265l 3.00-Inch Crank1.815 CH (or 1.765 with the 262 crank)Either engine would be a big bore, de-stroked 305 that makes good use of this wholly disregarded block as a performance contender. The 305 has 2.45-inch mains, so this swap would need the later 265 crank offered in '94 or the 262 crank available in 1975-76, which, incidentally has a 3.10-inch stroke that would yield a slightly larger 276 cid. Either of these cranks will work because of their 2.45/2.100-inch journals. Or, as a last resort, you could use the early 265 crank or any of the 283 cranks, but since both of these First-Generation small-block cranks share the 2.30-inch mains and 2.00-inch rod journals on the crank, this can be a troublesome swap that most machine shops will try to talk you out of.
The 290-Cid Torquer3.766-Inch Bore 305 Block307/327l 3.25-Inch Crank1.690 CHWhile it's still just another de-stroked 305, we call this one the Torquer because its longer stroke will make a little more torque than the 267/276-cid Screamer. Parts for this one may be a little easier to come by because, even though only two years of 327 cranks will work, there are still plenty of them around. Only the '68-69 327s had 2.45-inch mains that'll drop right into the 305 journals. To make this swap easier, you could also use someone's unwanted 307 crank since they're basically the same as the late 327 cranks.
The 292-Cid Master3.780-Inch Bore 265l Block307/327l 3.25-Inch Crank1.690 CHThis one is known simply as the Master because it deserves it. Although the 265 block with the large 2.45-inch mains was only available in 1994, most of them have been left behind in favor of something bigger. Why not stroke it 1/4 inch and give it some new life? You'd probably have little trouble finding someone willing to give away a 307 crank that'll drop right in and make this stroker an easy build. Any late 327 crank would work equally well.