LB1 and LB4

In 1985, the 4.3 L (262 cu in) was either equipped with throttle-body fuel injection (RPO LB4) or a Rochester Quadrajet four-barrel carburetor (RPO LB1). The Chevrolet Caprice, Chevrolet Monte Carlo, Chevrolet El Camino, Pontiac Parisienne, and Pontiac Grand Prix used the LB4 rated at 130 hp (97 kW). Pickups and vans used the LB1 version rated at 155 hp (116 kW). The LB1 used in trucks and vans was referred to as Vortec in Chevrolet literature (named after a combustion chamber design known as a swirl port which twists the fuel mix from the intake ports as introduced with the Cavalier's 2.0L engine), and this name continued to be used with all truck and van 4.3 L (262 cu in) V6s until 2014.

In 1986, the 4.3 L (262 cu in) engine used in passenger cars saw an increase in power to 140 hp (104 kW). This engine remained unchanged until 1990 when it was last used in taxi (RPO 9C6) and police (RPO 9C1) Chevrolet Caprices. In 1986, the Chevrolet Astro and GMC Safari vans used the fuel-injected LB4 instead of the LB1. In 1987, the Chevrolet full-size pickups and vans were upgraded to use the LB4 throttle-body injection version of the 4.3 L (262 cu in). The mechanical fuel pump boss was retained but the hole was undrilled (marine applications had the fuel pump boss drilled and tapped). From 1987 onwards, the LB4's output was 160 hp (119 kW) for pickups, while full-size vans were rated at 150 hp (112 kW). In 1988, the S-10/S-15 trucks, S-10 Blazer, and S-15 Jimmy had the LB4 4.3 L (262 cu in) as an available option (the accessory drive was upgraded to a serpentine belt drive), which later replaced the 2.8L as the base V6. The LB4 continued until 1996 with minor variations in power, but without any major changes. While a majority of LB4s did not have a balance shaft, some 1994 model year engines may have a balance shaft since production of the cylinder block used on the L35 was phased in for both induction systems. The 1994 model year was the final time a non-balance shaft cylinder block was used; production 1995 TBI engines were all balance-shaft engines.

Legend

• 1 – Chevrolet C/K trucks, GMC C/K trucks
• 2 – Chevrolet G-series vans, GMC G-Series vans
• 3 – Chevrolet Astro vans, GMC Safari vans (Note: LB1 for 1985 only and LB4 not available 1995)
• 4 – 1985 Chevrolet Impala, 1985–1988 Chevrolet Caprice, 1989–1990 Chevrolet Caprice police/taxi only, 1985–1986 Pontiac Parisienne
• 5 – 1985–1988 Chevrolet El Camino, GMC Caballero, Chevrolet Monte Carlo, 1986–1987 Pontiac Grand Prix (Note: 140 hp (104 kW) LB4 used 1986 only)
• 6 – 1988–1994 Chevrolet S-10 Blazer, GMC S-15 Jimmy, and 1991 Oldsmobile Bravada
• 7 – 1988–1995 Chevrolet S-10 and GMC S-15/Sonoma

LU2

For the 1990–1991 model years, a high-output 4.3 L (262 cu in) V6 was an available option for the extended-length versions of the Chevrolet Astro and GMC Safari vans. The LU2 used unique hypereutectic, strutless pistons and a more aggressive camshaft. Like the LB4, the LU2 used throttle-body fuel injection, but was rated at 170 hp (127 kW) and 225 lb⋅ft (305 N⋅m) of torque. This engine was replaced in 1992 with the L35.

Legend

• 1 – Chevrolet Astro vans, GMC Safari vans; optional on extended-length models only

L35 CPI

1992 introduced a new version of the 4.3 L (262 cu in), the L35. This version of the 4.3 L (262 cu in) was equipped with CPI (Central Port Fuel Injection). This system had one centrally-located fuel injector to distribute fuel to six hoses each with a poppet valve to each of the intake ports. This system allowed for a multi-point fuel injection, using one injector. The fuel injection was a batch fire system and used a two piece cast aluminum dual-plenum manifold. This engine was available in Chevrolet S-10/GMC Sonoma pickups, Chevrolet S-10 Blazer/GMC S-15 Jimmy/Oldsmobile Bravada SUVs, and Chevrolet Astro/GMC Safari vans only. The L35 was rated at 200 hp (149 kW) and 260 lb⋅ft (353 N⋅m) of torque.

The cylinder block was redesigned for use with a balance shaft. Cylinder heads (10238181 casting) used with the L35 have intake ports with eyebrows that clear the fuel injectors. Timing cover flange area was thickened in 1995 when some of the balance shaft motors had a six-bolt timing cover; some engines had a crankshaft position sensor (in conjunction with a redesigned distributor containing a pickup assembly which functions as a camshaft position sensor) when OBD-II was phased in.

Legend

• 1 – Chevrolet Astro vans, GMC Safari vans (Note: standard on AWD, optional on 2WD models)
• 2 – Chevrolet S-10 Blazer, GMC Jimmy, Oldsmobile Bravada (Note: Oldsmobile Bravada not produced in 1995)
• 3 – Chevrolet S-10, GMC Sonoma (engine standard equipment with the S10 SS and Sonoma GT)

L35 and LF6 SCPI and MPFI

Major design changes were made to the 4.3 L (262 cu in) V6 for the 1996 model year. Like other small block Chevrolet V8s, the 4.3 L (262 cu in) engine received redesigned heads which had improved airflow and combustion efficiency. These heads are referred to as Vortec heads.

The engine block was revised with structural reinforcing ribs up front eliminating the two freeze plugs (on the front and back) along with an alloy oil pan (for the S-10, Blazer, and Jimmy). The 1996+ cast aluminum oil pan has 12 bolts where a 16-bolt oil pan from the earlier 4.3 does not interchange. These 4.3 L (262 cu in) (1996–2000) engines came with a redesigned 4L60-E transmission with a removable bellhousing which bolts to the oil pan.

Crankshafts manufactured for the 1999 model year (to the end of 4.3 L (262 cu in) production) had a pilot hole depth of 1.41 in (35.8 mm) when coupled to the LSx-based 4L60E, which had a redesigned torque converter pilot hub (which was longer and was used with a 300 mm (11.8 in) stator shaft). The torque converter pilot hub was longer than the early 4L60E (similar in appearance to the 1993–1995 700R4) or the second generation variants (incorporating a removable bellhousing) with the GMT330 or 1996–1998 C/K series.

This engine came in two versions, the LF6 rated at 175–180 hp (130–134 kW), and the L35 rated at 180–200 hp (134–149 kW). Only the S-series pick-ups used the LF6, while the full-size trucks, vans and Blazer and Jimmy used the L35 version. The L35 was optional on the S-Series trucks.

Legend

• 1 – Chevrolet/GMC C/K trucks
• 2 – Chevrolet Express/GMC Savana vans
• 3 – Chevrolet Astro/GMC Safari vans
• 4 – Chevrolet Blazer/GMC Jimmy, 1996–2001 Oldsmobile Bravada SUVs
• 5 – Chevrolet S-10/GMC Sonoma trucks (2WD)
• 6 – Chevrolet S-10/GMC Sonoma trucks (4WD)
• 7 – Chevrolet Silverado/GMC Sierra trucks

LU3 and LG3 MPFI

2002 saw major changes to the 4.3 L (262 cu in) fuel-injection system. For 2002, the Chevrolet Astro, GMC Safari, Chevrolet Silverado, and GMC Sierra all came equipped with the updated LU3 4.3 L (262 cu in) in California emissions states. 2003 saw the L35 discontinued and the LU3 replacing it in all other applications. A new variation was also introduced in 2003, the LG3. From 2004 to 2014, the LU3 was the only 4.3 L (262 cu in) produced.

The biggest change to the LU3 and LG3 was the fuel-injection system. These engines used a multipoint fuel-injection system, with six Multec II fuel injectors mounted at each intake port on the manifold. GM recommends the Multec II spider assembly (which is also available for the L30 and L31 small block V8 motors) as a replacement for the 1996–2002 SCPI injector/spider assembly since the poppet valves have been known to stick open. The sticking poppet valves have been attributed to ethanol fuel blends sold in the State of California. The composite upper intake manifold and cast aluminum lower intake from the L35 engine is also used on the LU3. The LG3 uses a cast aluminum upper intake and a cast iron lower intake.^[7] The lower intake eliminated the EGR valve.

The LU3 also received a "quiet cam" to help reduce vibration at both idle and high engine speeds. This camshaft used the same lift and duration as the older design, but the cam was reprofiled to keep the valve lifters in full contact with the cam lobes as the cam ramps down.^[7]

The LG3 was used in Chevrolet S-10 and GMC Sonoma pickups and was only produced for 2003. The LU3 was used in the Chevrolet and GMC full-size trucks and vans, the Chevrolet Astro and GMC Safari vans, and the Chevrolet S-10 Blazer and GMC S-15 Jimmy. The LG3 was rated at 180 hp (134 kW) and 245 lb⋅ft (332 N⋅m) of torque. The LU3 was rated at 190–200 hp (142–149 kW) and 250–260 lb⋅ft (339–353 N⋅m) of torque.

For the 2007–2013 GMT900 Silverado/Sierra 1500 trucks and 2008–2014 Express/Savana 1500 vans, the LU3 engine received a Distributorless Ignition System: the traditional distributor was eliminated where a stub shaft was used. In addition, the crankshaft sensor was upgraded to a 58x reluctor wheel (same as the GEN IV LSx) which resulted in the timing cover redesigned (this time, the cover is aluminum alloy in lieu of the composite cover); the timing cover bolt pattern is not the same as the 1996–06 LU3 and L35.

Legend

• 1 – Chevrolet Silverado and GMC Sierra 1500 trucks
• 2 – Chevrolet Express and GMC Savana vans
• 3 – Chevrolet Astro and GMC Safari vans
• 4 – Chevrolet Blazer and GMC Jimmy SUVs
• 5 – Chevrolet S-10 and GMC Sonoma trucks (2WD)
• 6 – Chevrolet S-10 and GMC Sonoma trucks (4WD)

Turbocharged LB4 4.3L V6

1993 GMC Typhoon engine

In 1991, GMC introduced the GMC Syclone limited-edition truck that used a turbocharged 4.3 L (262 cu in) V6. This engine used a Mitsubishi TD06-17C turbocharger, Garrett water/air intercooler, and electronic multi-point fuel injection. Although GM made these modifications to the engine, it was still referred to with the RPO LB4 code. The majority of the naturally aspirated LB4's long-block was shared with the turbo version. However, the vehicles that used the 4.3 L (262 cu in) turbo engine also included RPO code ZR9. Internal engine upgrades included nodular iron main bearing caps, graphite composite head gaskets with stainless steel flanges, and hypereutectic pistons which lowered the engine compression to 8.35:1.^[8] A unique intake manifold that used the 48 mm (1.9 in) twin-bore throttle body from the 5.7L TPI Corvette engine was used on the engine's top end.^[9]

The turbocharged 4.3 L (262 cu in) was last used in the GMC Typhoon in the 1993 model year. The engine produced 280 hp (209 kW) at 4400 rpm and 360 lb⋅ft (488 N⋅m) of torque at 3600 rpm.^[10]

LV3

The 4.3 L (262.5 cu in) LV3 V6 is an all-new engine announced by GM at the end of 2012. GM considers this a new engine design which inherits from its predecessors its displacement, 2-valve pushrod valvetrain, 90-degree cylinder angle, and 4.4 in (111.8 mm) bore centers. It is based on the fifth-generation LT engine and includes the same features such as direct injection, piston cooling jets, active fuel management, variable displacement oil pump, continuously variable valve timing, and aluminum cylinder heads and block. The engine is SAE certified to 285 hp (213 kW) at 5300 rpm and 305 lb⋅ft (414 N⋅m) at 3900 rpm on regular unleaded gasoline and 297 hp (221 kW) at 5300 rpm and 330 lb⋅ft (447 N⋅m) at 3900 rpm on E85. Emissions are controlled by a close-coupled catalytic converter, Quick Sync 58X ignition, returnless fuel rail, and fast-response O₂ sensor.^[11] It was launched in the all-new 2014 Chevrolet Silverado and GMC Sierra 1500.^[12] 2021 was its final model year in the Chevrolet Silverado and GMC Sierra 1500, as the 6-speed automatic transmission was phased out. The Chevrolet Express and GMC Savana are the last vehicles to use the 4.3L but do not feature Active Fuel Management and their version of the engine is referred to as the LV1.

Applications:

• 2014–2021 Chevrolet Silverado 1500
• 2014–2021 GMC Sierra 1500

LV1

The LV1 engine is essentially the same as the LV3, but without Active Fuel Management technology. The LV1 made its debut in the 2018 model year GM full-size vans—the 2018 Chevrolet Express and GMC Savana—as the successor to the 4.8L Vortec engine.