Mark IV Big Block Chevy Engine - The Mark of Chevy Power

Where Chevy Muscle Really Lives

Paul Zazarine Nov 1, 2006 0 Comment(s)
Sucp_0607_rat_07_z Chevy_mark_iv_big_block_motor 1967_l71_427_carbs 1/11

One of the most famous big-blocks is the '67 L71. This 427 was rated at 425 hp, and a thumpin' 460 lb-ft of torque. A trio of Holley two-barrel carburetors drew air through a triangular-shaped air cleaner with a low-restriction polyurethane element.

Sucp_0607_08_z Chevy_mark_iv_big_block_motor 1969_ZL1_v8 2/11

The King Kong of the Mark IV family was the '67-'69 L88. It differed very little from the '69 all-aluminum ZL1 shown here. The major difference was that the L88 used an iron block. Both engines were ridiculously underrated at 430 hp, and were true race engines. Chevrolet sold just 216 L88-equipped Corvettes between 1967 and 1969. Only two ZL1s were installed at the factory in '69 Corvettes. A total of 69 ZL1s were installed in '69 Camaros under special Central Office orders. The ZL1 had a 12:1 compression ratio and used an alloy aluminum block with dry cylinder sleeves. Aside from that major difference, it and the L88 were virtually the same. Both used mechanical lifters and 1.70:1 rockers. The ZL1 and the L88 both used 2.185-inch intake and 1.875-inch exhaust valves made of alloy steel. The intake valve face and head was aluminized, while only the exhaust valve's face was aluminized. The L88 had 0.5500 lash at zero lift while the ZL1 had 0.5800 lift at zero lash.

Sucp_0607_rat_09_z Chevy_mark_iv_big_block_motor LS5_454_v8 3/11

In 1970, the Mark IV was treated to a 0.24-inch bore job, taking it out to 4.00. With the 4.25 stroke unchanged, the new engine displaced 454 ci. The LS5 version produced 390 hp with a hydraulic valvetrain. It was also stymied by emission control equipment.

Sucp_0607_rat_10_z Chevy_mark_iv_big_block_motor 1970_corvette_LS7 4/11

This is the engine that never was, at least in production form. It's the LS7, and it was destined for the '70 Corvette. None were ever installed at the St. Louis assembly plant. The 460hp LS7 in this factory photo shows a trio of Holley two-barrel carburetors. Factory specifications, however, indicate that a Holley four-barrel was planned, along with aluminum heads, 11.25:1 compression, a mechanical valvetrain, and a transistorized ignition.

Sucp_0607_rat_11_z Chevy_mark_iv_big_block_motor ZZ502_crate_motor 5/11

The ZZ502/502 is one of GM's most popular crate engines. It features a complete roller-rocker valvetrain, big-valve aluminum heads, and a dyno-tuned induction and ignition system. It's lightweight, and can be ordered as a long-block or a complete engine kit.

Sucp_0607_rat_12_z Chevy_mark_iv_big_block_motor ZZ572_crate_motor 6/11

The "King of the Crate Engines" is the new ZZ572/620 that's built around an all-new Gen VI tall deck Bow-Tie big-block. This all-new engine is filled with a forged 4340 steel crank with 4.375-inch stroke, shot-peened, forged 4340 H-beam rods, and forged-aluminum pistons with full-floating wristpins. The 572 makes 620 hp at 5,500 rpm, and 650 lb-ft of torque at 4,500 rpm.

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