Chevy 4.3 Information

by Rob Wagner

The Chevy 4.3-liter V-6 engine is a durable, compact motor used to power Chevrolet trucks, vans and some passenger cars. Although it displaces only 262 cubic inches, it is powerful enough to power full-size trucks. For more than 25 years the Chevy 4.3 filled a niche between the 5-liter V-8s and the inline four-cylinder engines. It is perhaps Chevrolet’s most popular six-cylinder engine.


The versatile 4.3-liter V-6 debuted in 1985 to replace the venerable 229-cubic-inch V-6 that was a mainstay for the El Camino, in which production was drawing to an end, and full-size Chevy passenger cars. The Chevy 4.3 also served to replace the 250 V-6 found in full-size trucks and vans, according to

Early Version

The initial 4.3 featured a 4-inch bore and 3.48-inch stroke. It had the same dimensions as the 350 V-8--hence its nickname, the "three-quarter 350." Equipped with a four-barrel carburetor and a 9.3-1 compression ratio, the 1985 version of the 4.3 was capable of 155 horsepower and 230 pound-feet of torque, the twisting power generated for quick acceleration. A less powerful version generated 130 horsepower and 210 pound-feet of torque.


In 1992, Chevrolet focused on minimizing vibration by placing the balance shaft on top of the top timing gear and redesigning the timing chain cover to accommodate the change. The result was a smoother running engine. Further, the compression ratio was dropped to 9.1-1. Horsepower was increased to 170 and torque to a fairly generous 260 pound-feet.


The Chevy 4.3-liter engine proved so popular it was placed in Chevrolet and GMC C/K trucks, Chevrolet and GMC G-Series vans, the Astro and Safari minivans, the Impala and Caprice police and taxi vehicles. The Monte Carlo, Pontiac Grand Prix, compact Chevy S-10 trucks, Chevy Blazer SUV and El Camino also were equipped with the 4.3.

Major Changes

The Chevy 4.3 underwent two major renovations to develop better efficiency, smoother operation and to create more horsepower. In 1996, the air-fuel mixture flow was improved thanks largely to completely redesigned heads. This brought the 4.3-liter into the Vortec engine family and was marketed as the Vortec 4300. The block was reinforced and an alloy oil pan was added for the S-10 truck, and Chevy Blazer and GMC Jimmy SUVs. In 2002, the fuel injection system was changed to a multiport system to accommodate California emissions requirements. During this period, power was boosted to 200 horsepower and 250 pound-feet of torque.


A turbocharged version of the Chevy 4.3 made a brief appearance from 1991 through 1993. The engine was used in the GMC Syclone and the GMC Typhoon. These two short-wheelbase SUVs were produced in very limited numbers and employed a Mitsubishi turbocharger and Garrett water-air intercooler and electronic fuel injection. The turbocharged 4.3 generated an impressive 280 horsepower and 360 pound-feet of torque.

About the Author

Rob Wagner is a journalist with over 35 years experience reporting and editing for newspapers and magazines. His experience ranges from legal affairs reporting to covering the Middle East. He served stints as a newspaper and magazine editor in Saudi Arabia and the United Arab Emirates. Wagner attended California State University, Los Angeles, and has a degree in journalism.