383 Stroker Engine: Why The Chevy Small Block Is Still A Muscle Car Favorite
When Goldilocks got a hankering to break into a house owned by bears, she didn't realize her name would forever be defined as "just right." Something in the "Goldilocks zone" means that it occupies a sweet spot between two extremes, and the 383 small block Chevy is the baby bear's porridge of V8s. But unlike the Camaro Z28 (or Z/28 or Z-28), and its 302, the 383 wasn't the result of Chevy trying to achieve some sort of rule-following displacement.
The 383 didn't have an officially sanctioned birth. Rather, it likely was progenated by the late Joe Sherman, an engine builder who thought like Ed Harris in "Apollo 13," shouting at his piles of Chevy engine parts, "I don't care what anything was designed to do, I care about what it CAN do." As far as anyone knows, Sherman was the first to take a 400 small block crank, shave the journals so it would slot into a 350 block, then overbore said block by 0.030 inches. The resulting engine displaced 382.6 cubic inches, a lovely 32.6-ci increase.
What makes the 383 a killer replacement for the 350 isn't just the added displacement, though, it's the significant torque advantage. Most of the added inches come from the longer stroke of the 400 crank, and upping stroke increases leverage, which increases torque, which increases smiles. And 383s don't just make more torque than 350s, they make their torque at lower rpm. If you want to blast off the line or just experience eye-widening acceleration with every tap of the gas, a 383's low-end grunt is what you want.
Why not just use the 400 small block you pulled from the scrapyard?
If the extended-stroke 383 small block sits in the Goldilocks zone, wouldn't expanding that to 400 put some pep in her step, like adding a 5 Hour Energy to baby bear's porridge? You'd get 17 more cubic inches and you wouldn't have to machine the crank, either. Well, traditionally, hot-rodders ignored the 400 because it had (and has) a reputation for overheating, which is almost entirely due to its Siamese bores.
When boring out the small block to create the 400, Chevy realized the cylinder walls were awfully thin. The solution was to give the 400 Siamese bores, or solid castings with no water passages between the cylinders. This design increases strength, which is why Dart loves Siamese bores, but it does create overheating issues without fastidious maintenance and a stellar cooling system.
Chevy gave the 400 steam holes to help with cooling, but the stock heads are susceptible to cracking under strain, meaning you have to swap the top end to make power. But if you don't drill a set of steam holes into the new heads to mate up with the block, you could face cracked cylinder walls as the heat and pressure build up. Since the 400 apparently isn't concerned about making itself likable, it also features an externally balanced rotating assembly, making part-swapping with other small blocks a major headache.
Chevrolet introduced the 400 in 1970 and abandoned it in 1979. The Cadillac Northstar V8 eventually turned itself around after a decade or so of reliability and durability woes, but the solution for the 400 was tossing it down a well and saying, "What 400?"
You don't have to know the recipe for a 383 anymore, just order one to go
These days, if you want a turnkey 383 that isn't a Mopar product, you have options. You can still scour scrapyards for discarded 400s to dissect, but buying an aftermaket crate 383 is easier. What's really cool about the glut of new 383 parts is that builders no longer have to rely on old cast cranks and rods, but can select forged bits to withstand massive power. If you want cheaper cast cranks/rods, great, they can still handle 500 hp without issue. ATK, Blueprint, Dart, and now even Chevrolet will sell you new or refurbished 383 blocks, short blocks, or complete engines to fit budgets ranging from Jeff Bezos to frugal janitor.
When Chevrolet Performance's SP383 debuted in 2020, it featured a 4-inch bore and a 3.8-inch stroke. Perhaps someone with keen math sensitivity complained that this combination yielded a displacement of 382.02 ci because Chevy's website says the bore is now 4.005 inches, which results in 382.97 ci. You'd hate for those aftermarket 383 emblems to lie, wouldn't you?
No, inaccurate displacement badges are more of a Mercedes and Ford thing (looking at you, "6.3" and "5.0" V8s). And no, Mercedes didn't call its 6.2 a 6.3 to comply with any laws or German tax regulations. When Autoweek asked Mercedes why it called a 6,208 cc V8 a "6.3," Mercedes responded, "the Germans like to round up." As for Ford, apparently calling its 302 Windsor a "5.0" was to avoid confusion with (and imply superior performance to) the company's 4.9-liter inline six. This is playful shade, by the way — I'd happily trade unwanted internal organs for a clean 6.8-liter Mercedes 450SEL 6.9 or my grandfather's long-ago-sold '82 Mustang GT.