







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 2000’s. 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 form these engines have earned them a place in automotive history.

Video Posted on YouTube By: Jeff Quitney

Mark I W Series

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

Mark I W Series Horse Power Ratings

Cubic Inches Bore and Stroke Gross Advertised Power Model Carburetion Production Years 1 348 4.125 x 3.250 250 hp (190 kW) Turbo Thrust 4 Barrel 1958-1961 2 348 4.125 x 3.250 280 hp (210 kW) Super Turbo Thrust Triple 2 Barrel 1958-1961 3 348 4.125 x 3.250 305 hp (227 kW) 4 348 4.125 x 3.250 315 hp (235 kW) 5 348 4.125 x 3.250 320 hp (240 kW) 6 348 4.125 x 3.250 335 hp (250 kW) 7 348 4.125 x 3.250 340 hp (250 kW) 8 348 4.125 x 3.250 350 hp (260 kW) 9 409 4.312 x 3.500 360 hp (268 kW) 4 Barrel Carter 1961 10 409 4.312 x 3.500 380 hp (283 kW) 4 Barrel Carter 1962 11 409 4.312 x 3.500 409 hp (305 kW) Dual 4 Barrel 1962 12 409 4.312 x 3.500 425 hp (317 kW) Dual 4 Barrel 1963-1965 13 409 4.312 x 3.500 340 hp (254 kW) 4 Barrel Rochester 1963-1965 14 427 4.312 x 3.650 430 hp (320 kW) Z11 1963 15 427 4.312 x 3.650 575 lb·ft (780 N·m) Z11 1963

Mark II

The Mark II were race only engines produce only 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.

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 1 396 4.094 x 3.760 360 hp (270 kW) L34 4 Barrel 1966-1969 2 396 4.094 x 3.760 325 hp (242 kW) L35 4 Barrel 1965-1969 3 396 4.094 x 3.760 375 hp (280 kW) L37 4 Barrel 1965 4 396 4.094 x 3.760 265hp (198 kW) L66 2 Barrel 1969 5 396 4.094 x 3.760 375 hp (280 kW) L78 4 Barrel 1965-1969 6 396 4.094 x 3.760 425 hp (317 kW) L78 Corvette 4 Barrel 1965-1969 7 402 4.124 x 3.760 330 hp (250 kW) LS3 4 Barrel 1970 8 402 4.124 x 3.760 300hp (220 kW) LS3 4 Barrel 1971 9 402 4.124 x 3.760 240hp (180 kW) LS3 4 Barrel 1972 10 402 4.124 x 3.760 375 hp (280 kW) L78 4 Barrel 1970 11 427 4.250 x 3.760 390 hp (290 kW) L36 4-barrel 1966-1969 12 427 4.250 x 3.760 425 hp (317 kW) L72 4-barrel 1966-1969 13 427 4.250 x 3.760 400 hp (300 kW) L68 Triple 2 Barrel 1967-1969 14 427 4.250 x 3.760 435 hp (324 kW) L71 Triple 2 Barrel 1967-1969 15 427 4.250 x 3.760 435 hp (324 kW) L89 Triple 2 Barrel 1967-1969 16 427 4.250 x 3.760 430 hp (320 kW) L88 1967-1969 17 427 4.250 x 3.760 430 hp (320 kW) ZL1 1969 18 427 4.250 x 3.760 430hp (3210kW) ZLX 1970-1977 19 454 4.250 x 4.000 390 hp (291 kW) LS5 4-barrel 1970 20 454 4.250 x 4.000 450 hp (340 kW) LS6 4-barrel 1970 21 454 4.250 x 4.000 465 hp (347 kW) LS7 1970 22 454 4.250 x 4.000 365 hp (272 kW) LS5 1971 23 454 4.250 x 4.000 425 hp (317 kW) LS6 1971 24 454 4.250 x 4.000 270 hp (200 kW) LS5 1972 25 454 4.250 x 4.000 275 hp (205 kW) LS4 1973-1976 26 454 4.250 x 4.000 235 hp (170 kW) EFI 1987-1990

Generation V

For 1991 GM changed the designation of big blocks to “Generation V” do to the fact that Ford was using the “Mark” name in some Lincoln car models. Significant changes and upgraded were maid 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









Generation VI

For the 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

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 head, 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

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