Big Block vs Small Block Chevy: Differences

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October 4, 2026
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Big Block vs Small Block Chevy: Differences, Sizes and Which to Choose

“Small block” and “big block” name two different engine families, not just two sizes. A big block has a physically larger block with more space between the cylinders: on a Chevy, the bore spacing is 4.840″ on the big block against 4.400″ on the small block. That extra room allows bigger bores and more displacement, so big blocks usually make more torque, but they are also wider, taller and heavier. Displacement alone does not decide it: GM’s 7.0L (427 cubic inch) LS7 is a small block, while the 1965 396 is a big block.

Small block vs big block Chevy at a glance

	Small block Chevy (SBC)	Big block Chevy (BBC)
Bore spacing	4.400″	4.840″
Classic factory sizes	262 to 400 cubic inches (305, 327, 350, 400 and more)	396, 402, 427 and 454 cubic inches
Popular crate sizes	350, 383 stroker, 396 and 400	454, 502, 572 and 632
Cylinder heads	Valves in line	Canted valves (“porcupine” heads)
Size and weight	Compact and lighter	Wider, taller and heavier
Firing order	1-8-4-3-6-5-7-2	1-8-4-3-6-5-7-2
Typical use	Street cars, hot rods, swaps into tight engine bays	Muscle cars, trucks, boats and torque-focused builds

The two share their firing order and the Chevrolet V8 bellhousing pattern, but blocks, heads, intakes, pistons and rods do not interchange. GM’s LS and LT engines keep the small block’s 4.400″ bore spacing, so they are small blocks too; see GM LS engines explained.

350 vs 454

	Chevy 350 (small block)	Chevy 454 (big block)
Displacement	350 ci (5.7L)	454 ci (7.4L)
Bore x stroke	4.000″ x 3.480″	4.250″ x 4.000″
Our crate engine ratings	330 to 405 HP	438 and 460 HP
Our crate engine prices	From $4,899	From $8,972

The 454 makes more torque at low rpm, which suits heavy cars, trucks and towing. The 350 is lighter, fits more engine bays and leaves more budget for the rest of the car. Read the full specs in our Chevy 350 engine guide and Chevy 454 big block guide.

Is a 383 a small block or a big block?

A 383 stroker is a small block. It is a 350-size block with a longer 3.750″ stroke crankshaft, so it keeps the small block’s external size and mounts. See our 383 stroker engine guide. The same goes for the small block 396 and 400 crate engines, which should not be confused with the big block 396 of the 1960s.

Ford and Mopar small blocks and big blocks

Ford: the Windsor small blocks include the 302 and 351W; the 429 and 460 are Ford big blocks. See our Ford 302 engine guide.
Mopar: Chrysler’s small blocks include the 318, 340 and 360; the 383 and 440 are big blocks, and the 1960s 426 Hemi was a separate big engine of its own. See our 426 Hemi engine guide.

As with Chevy, a stroked small block can match a factory big block’s displacement while keeping the smaller external size.

Which should you choose?

Choose a small block for most street cars, tight engine bays, lighter front ends and lower cost. A 383 stroker adds torque without the size of a big block.
Choose a big block when torque is the priority (heavy cars, trucks, towing, big-displacement drag builds) and the chassis has room for a wider engine, more cooling and a stronger transmission and axle.
Check fit first: hood clearance, headers and steering, engine mounts, radiator size and the transmission.

Small block and big block Chevy crate engines here

Engine	Family	Rating	Price
BluePrint SBC 350 long block (BP350CT)	Small block	341 HP, 371 lb-ft	$4,899.00
GM Performance ZZ6 350	Small block	405 HP	$7,982.95
BluePrint SBC 383 base dressed engine (BP38318CTC1)	Small block	436 HP	$6,599.00
BluePrint SBC 396 (BP3961CT)	Small block	491 HP	$7,649.00
BluePrint SBC 400 long block (BP4002CT1)	Small block	500 HP	$7,349.00
GM Performance 454 HO	Big block	438 HP	$8,971.95
BluePrint BBC 454 base engine (BP454CT)	Big block	460 HP	$9,099.00
GM Performance 502	Big block	461 HP	$10,195.00
GM Performance ZZ502	Big block	508 HP	$14,319.05
GM Performance 572/720	Big block	720 HP	$20,062.95
BluePrint 632 Pro Series	Big block	815 HP	$17,149.00

Prices change, so check the product page for the current price. Every order ships for a flat $75 to any US state. See all small block Chevy crate engines and big block Chevy crate engines.

Frequently asked questions

What is the difference between a small block and a big block?

A big block is a physically larger engine family with wider bore spacing (4.840″ on a Chevy, against 4.400″ on a small block), which allows more displacement. It is heavier and wider, and it usually makes more torque.

Is a 454 a big block?

Yes. The Chevy 454 (7.4L) is a big block, as are the 396, 427, 502 and 572.

Is an LS engine a small block?

Yes. GM’s LS engines are Gen III and Gen IV small blocks with the same 4.400″ bore spacing as the original small block Chevy, even the 7.0L LS7.

Is a big block better than a small block?

Not automatically. A big block makes more torque, but a small block is lighter, fits more cars and costs less. Pick the family that suits the vehicle and how it will be used.

Do small block and big block Chevy engines share parts?

They share the firing order and the Chevrolet V8 bellhousing pattern, but blocks, heads, intakes, pistons and rods are different.

What is a big block engine?

A big block is a V8 built on a physically larger engine block, with wider spacing between the cylinder bores than the same maker’s small block. The extra room allows bigger bores and more displacement, so big blocks are usually chosen for torque, but they are wider, taller and heavier. The Chevy 454, 502 and 572 are big blocks; browse our big block Chevy crate engines.

What is a small block engine?

A small block is a V8 built on the more compact of a maker’s engine block designs, with closer bore spacing and a narrower, lighter block than its big block. The name describes the block family, not the displacement: the Chevy 350 and 383 and GM’s LS engines are all small blocks. Browse our small block Chevy crate engines or read SBC vs LS.