The Chevrolet Big Block V8 Engine – The Rat Motor
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″ |
Other Chevy Big Block Info
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
Chevrolet Big Block Tune-Up and Torque Specifications
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