The Chevrolet Big Block V8 Engine – The Rat Motor

Chevrolet Big Block 454

The Chevrolet Big Block V8 Engine – A Brief History and Evolution of The Chevy Rat Motor

The Chevrolet Big Block is one of the most familiar and long-running Big Block engines. Nicknamed the Rat Motor, the Chevrolet big block’s long history started in 1958 with the introduction of Chevy’s all-new 348 cubic inch engine. Chevy’s big-block had a long run with variations up to 572 cubic inches and was produced well into the 2000s. Big Block engines were installed in many muscle cars including Camaro, Chevelle, Nova, Impala Corvette, and more. Amazing power, high revving capabilities, and brute force from these engines have earned them a place in automotive history.

Chevrolet Big Block Engine Identification – Casting Numbers, Date & Engine Codes

Chevrolet Big Block Heads – Casting Numbers and Specifications

Big Block Chevrolet Engine Intake and Exhaust Manifolds Info and Casting Numbers

The Chevrolet Big Block Camshaft Part Numbers

Mark I W Series

The first Chevrolet Big Block V8 engine was the W Series. Produced from 1958 to 1965, the engine had W-shaped valve covers due to its offset overhead valve design. Mark I engines were used in Chevy cars and trucks and were available in three displacements, 348 cubic inches, 409 cubic inches, and 427 cubic inches.

Chevrolet 409 Big Block

Mark I W Series Horse Power Ratings

Cubic Inches	Bore and Stroke	Gross Advertised Power	Model	Carburetion	Production Years
348	4.125 x 3.250	250 hp (190 kW)	Turbo Thrust	4 Barrel	1958-1961
348	4.125 x 3.250	280 hp (210 kW)	Super Turbo Thrust	Triple 2 Barrel	1958-1961
348	4.125 x 3.250	305 hp (227 kW)
348	4.125 x 3.250	315 hp (235 kW)
348	4.125 x 3.250	320 hp (240 kW)
348	4.125 x 3.250	335 hp (250 kW)
348	4.125 x 3.250	340 hp (250 kW)
348	4.125 x 3.250	350 hp (260 kW)
409	4.312 x 3.500	360 hp (268 kW)		4 Barrel Carter	1961
409	4.312 x 3.500	380 hp (283 kW)		4 Barrel Carter	1962
409	4.312 x 3.500	409 hp (305 kW)		Dual 4 Barrel	1962
409	4.312 x 3.500	425 hp (317 kW)		Dual 4 Barrel	1963-1965
409	4.312 x 3.500	340 hp (254 kW)		4 Barrel Rochester	1963-1965
427	4.312 x 3.650	430 hp (320 kW)	Z11		1963
427	4.312 x 3.650	575 lb·ft (780 N·m)	Z11		1963

Mark II

The Mark IIs were race-only engines produce only in 1963. Variations of the Mark II included 396, 409, and 427 cubic inches and included aspects of both the W-series and the Mark IV engines.

Mark III

Never Produced By Chevrolet.

Chevrolet Big Block V8 Engine 427 ci

Mark IV

The Mark IV engines shared many dimensions and features of the W series, but to improve higher RPM performance a new redesigned conventional wedge shape combustion chamber was used, the valve angle was changed, and the spark plugs were also repositioned.

Mark IV Series Horse Power Ratings

Cubic Inches	Bore and Stroke	Gross Advertised Power	Model	Carburetion	Production Years
396	4.094 x 3.760	360 hp (270 kW)	L34	4 Barrel	1966-1969
396	4.094 x 3.760	325 hp (242 kW)	L35	4 Barrel	1965-1969
396	4.094 x 3.760	375 hp (280 kW)	L37	4 Barrel	1965
396	4.094 x 3.760	265hp (198 kW)	L66	2 Barrel	1969
396	4.094 x 3.760	375 hp (280 kW)	L78	4 Barrel	1965-1969
396	4.094 x 3.760	425 hp (317 kW)	L78 Corvette	4 Barrel	1965-1969
402	4.124 x 3.760	330 hp (250 kW)	LS3	4 Barrel	1970
402	4.124 x 3.760	300hp (220 kW)	LS3	4 Barrel	1971
402	4.124 x 3.760	240hp (180 kW)	LS3	4 Barrel	1972
402	4.124 x 3.760	375 hp (280 kW)	L78	4 Barrel	1970
427	4.250 x 3.760	390 hp (290 kW)	L36	4-barrel	1966-1969
427	4.250 x 3.760	425 hp (317 kW)	L72	4-barrel	1966-1969
427	4.250 x 3.760	400 hp (300 kW)	L68	Triple 2 Barrel	1967-1969
427	4.250 x 3.760	435 hp (324 kW)	L71	Triple 2 Barrel	1967-1969
427	4.250 x 3.760	435 hp (324 kW)	L89	Triple 2 Barrel	1967-1969
427	4.250 x 3.760	430 hp (320 kW)	L88		1967-1969
427	4.250 x 3.760	430 hp (320 kW)	ZL1		1969
427	4.250 x 3.760	430hp (3210kW)	ZLX		1970-1977
454	4.250 x 4.000	390 hp (291 kW)	LS5	4-barrel	1970
454	4.250 x 4.000	450 hp (340 kW)	LS6	4-barrel	1970
454	4.250 x 4.000	465 hp (347 kW)	LS7		1970
454	4.250 x 4.000	365 hp (272 kW)	LS5		1971
454	4.250 x 4.000	425 hp (317 kW)	LS6		1971
454	4.250 x 4.000	270 hp (200 kW)	LS5		1972
454	4.250 x 4.000	275 hp (205 kW)	LS4		1973-1976
454	4.250 x 4.000	235 hp (170 kW)	EFI		1987-1990

Chevrolet Big Block V8 Engine 454 ci

Chevrolet Big Block V8 Engine 572

Generation V

In 1991 GM changed the designation of big blocks to “Generation V” due to the fact that Ford was using the “Mark” name in some Lincoln car models. Significant changes and upgrades were made to the new Generation V Big blocks. The main oil galley was moved, a new non-adjustable valvetrain, new one-piece rear main seal, and all blocks came with 4 bolt mains. Displacements available were the 454, 502, and the monster 572 cubic inches only available aftermarket through the GM Performance Parts division.

Generation V Series Horse Power Ratings

Cubic Inches	Bore and Stroke	Gross Advertised Power	Carburetion	Production Years
454	4.250 x 4.000	255 hp (190 kW)	EFI	1991-1996
502	4.466 x 4.000	338 hp -600 hp	EFI	1991-1996
572	4.560 x 4.375	620 hp – 720hp		1998

Chevrolet Vortec 7400

Generation VI

For Generation VI the big blocks were upgraded with a new hydraulic roller cam, a new multi-port fuel injection and were now called the Vortec 7400. The Vortec engines gave slightly more power and better fuel economy.

VI Series Horse Power Ratings

Cubic Inches	Bore and Stroke	Gross Advertised Power	Model	Carburetion	Production Years
454	4.250 x 4.000	290 hp (216 kW)	Vortec 7400 L29	MPFI	1996-2000
454	4.250 x 4.000	290 hp (216 kW)	Vortec 7400 L21	MPFI	1998-2001

Chevrolet Vortec 8100

Generation VII

The Generation VII Vortec 8100 was designed with an all-new iron block and heads. Changes include symmetrical intake ports, new firing order, 18 bolt heads, and longer connecting rods.

Generation VII Series Horse Power Ratings

Cubic Inches	Bore and Stroke	Gross Advertised Power	Model	Carburetion	Production Years
496	4.250 x 4.370	340hp to 550hp	Vortec 8100 L18	MPFI	2001-2009

Chevrolet Big Block Bore and Stroke

Engine	Bore	Stroke	Displacement
366	3.935″	3.760″	365.8″
396	4.094″	3.760″	396.0″
402	4.125″	3.760″	402.0″
427	4.250″	3.760″	426.0″
454	4.250″	4.000″	454.0″
502	4.468″	4.000″	501.7″