EJCP.PARTS

CHEVROLET 4.3 OHV 90DEG V6

The 4.3L (262 cid) V6 is the last and most successful engine in the Chevrolet 90-degree V6 engine family. This engine was introduced in 1985 as a replacement for the 229 cid V6 in the full-size Chevrolet, the Chevrolet El Camino and Monte Carlo. It also replaced the 250 cid in the Chevrolet full-size trucks and full-size vans (including the mid-sized Astro) as the new base six-cylinder engine. The 4.3L V6 has a 4.00-inch bore and a 3.48-inch stroke, identical to the 350 cid Chevrolet V8 engine. To create a true even fire engine, Chevrolet produced a crankshaft with 30-degree offsets between each rod pin. Consequentially, rod journals were increased to a larger 2.25 inches. The connecting rods used on the 4.3L are therefore unique to this engine, being 5.7 inches in length, but having the larger 2.25-inch journals. The 4.3L also used larger valves than the 229 cid V6, with a 1.94-inch intake valve and a 1.50-inch exhaust valve (also shared with the 350).[2] In 1986 and 1987, the 4.3L engine saw engine design upgrades similar to the Chevrolet small block V8. In 1986, the rear main crankshaft oil seal was changed from a two piece to a one piece seal. Some 1985 model year vehicles would have a 1986 engine due to service replacement - cylinder blocks were shipped with oil pans.[3] 1987 saw new center bolt valve covers and hydraulic roller lifters.[4] For the 1992 model year, the 4.3L had its block design modified to allow a balance shaft to be installed.[5] Even though the 4.3L is an even fire V6, the 90-degree block layout is not ideal for smoothness. The balance shaft on the 4.3L is installed above the top timing gear, and runs through the top of the lifter valley. It is gear driven off the timing chain, and therefore a new timing chain cover was designed for these balanced 4.3L V6s. Balance shaft engines do not have provisions for a mechanical fuel pump unlike the non-balance shaft motors which retained the cast in boss. As of the 2013 model year, the 4.3L was still in production although the distributor was eliminated in the late 2000s where a coil-on-plug ignition system was phased in. The only vehicles using the 4.3L were the GMT900 light duty trucks and vans. As of March 7, 2014, the last 4.3L engine rolled off the line at Romulus Powertrain. Mercury Marine, which sells its engines under the MerCruiser brand, developed a 4.5L V6 based on the 4.3L architecture using similar dimensions.[WIKI]

SIZES BLOCK MATERIAL HEAD MATERIAL CAM TYPE FUEL SYSTEM
4.3 CAST IRON CAST IRON OHV CARB
TBI
SMPFI

ITEMS

BRACKETS EXHAUST MANIFOLD INTAKE MANIFOLD OIL PAN PISTON
SENSORS TIMING COVER TIMING SET VALVE COVER VALVE INFORMATION

LISTING TEMPLATES LB1 LB4

In 1985, the 4.3L was either equipped with throttle-body fuel injection, RPO LB4 or a Rochester Quadrajet 4-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). Pick-ups 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 on the Cavalier 2.0L motor), and this name continued to be used with all truck and van 4.3L V6s until present day. In 1986, the 4.3L engine used in passenger cars saw an increase in power to 140 hp (100 kW). This engine remained unchanged until 1990 when it was last used in taxi and Police 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 pick-ups and full-size vans were upgraded to use the LB4 throttle-body injection version of the 4.3L. 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 LB4s output was 160 hp (120 kW) for pickups, while full-size vans were rated at 150 hp (110 kW). In 1988 the S-series trucks and S-Blazer and Jimmys had the LB4 4.3L as an available option (the accessory drive was upgraded to a serpentine belt drive), which later replaced the 2.8 as the base V6. The LB4 continued until 1996 with minor variations in power, but without any major change. 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.[WIKI]

SIZES COMPATABILITY ENGINE TEMP HEAD TEMP CRANK TEMP NOTES
4.3 OHV 85 ASTRO SAFARI 10 20 VAN FS 1500 2500 4.3A 4.3A ***** LB1 CARBORATED
4.3 OHV 86 ASTRO BONNEVILLE GRAND PRIX MALIBU MONTE CARLO SAFARI SPRINT
86-88 CAPRICE
4.3B 4.3A ***** LB4 TBI
4.3 OHV 87-92 ASTRO SAFARI FULL SIZE VAN
88-92 1500 2500
87 GRAND PRIX MALIBU
87-88 MONTE CARLO
89-92 CAPRICE
4.3A 4.3B ***** LB4 TBI
4.3 OHV 88-91 BLAZER JIMMY S10 S15 SONOMA 4.3C 4.3B ***** LB4 TBI
4.3 OHV 93 ASTRO CARPICE 1500 2500 FC VAN SAFARI 4.3E 4.3C ***** LB4 TBI
4.3 OHV 93-94 BLAZER JIMMY S10
94 ASTRO SAFARI
94-95 1500 2500
95-96 VAN
93-95 SONOMA
4.3D 4.3C ***** LB4 TBI
BALANCE SHAFT
NOTE PRESSED OR THREADED ROCKER STUDS

LISTING TEMPLATES LU2

For the 1990–1991 model years a high-output 4.3L V6 was an available option for 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 (130 kW) and 260 lb·ft (350 N·m) of torque. This engine was replaced in 1992 with the L35.[WIKI]

SIZES COMPATABILITY ENGINE TEMP HEAD TEMP CRANK TEMP NOTES
4.3 OHV 90-92 ASTRO SAFARI
88-92 BLAZER JIMMY S10 S15 SONOMA
91-92 BRAVADA
4.3D PRESS TYPE 4.3B
THREADED TYPE 4.3C
***** LU2 TBI HO

LISTING TEMPLATES L35

1992 introduced a new version of the 4.3L, the L35. This version of the 4.3L 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 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 Pickups Chevrolet Cheyenne C-1500 pickups and S10 Blazer/S15-Jimmys SUVs, Chevrolet Astro and GMC Safari vans only. The L35 was rated at 200 hp (150 kW) and 260 lb·ft (350 N·m) of torque. The cylinder block was redesigned for use with a balance shaft. Cylinder heads (10238181 casting) used with the L35 will 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 6 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 OBDII was phased in.[WIKI]

SIZES COMPATABILITY ENGINE TEMP HEAD TEMP CRANK TEMP NOTES
4.3 OHV 92-93 ASTRO SAFARI 4.3A 4.3C ***** L35 CPI
4X2
4.3 OHV 92-93 ASTRO SAFARI S10 SONOMA BRAVADA BLAZER JIMMY 4.3B 4.3C ***** L35 CPI
4X4 SAFARI ASTRO
4.3 OHV 94-95 ASTRO SAFARI 4.3C 4.3C ***** L35 CPI
4X2
4.3 OHV 94-95 ASTRO SAFARI S10 BLAZER SONOMA JIMMY BRAVADA 4.3D 4.3C ***** L35 CPI
4X4 ASTRO SAFARI

LISTING TEMPLATES LF6

Major design changes to the 4.3L V6 for the 1996 model year. Like other small block Chevrolet V8s, the 4.3L engine received redesigned heads which had improved airflow and combustion efficiency. These heads are referred to as Vortec heads. Furthermore the 4.3L was upgraded to receive sequential port fuel injection. The fuel system uses six centrally mounted injectors firing into six nylon hoses with poppet valves leading to each intake port. This system was called SCPI (Sequential Central Port Injection). This 4.3L used a two piece manifold, with the upper half manufactured from a composite plastic and the lower half manufactured from cast aluminum. 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 S10, Blazer, and Jimmy). The 1996+ oil pan has 12 bolts where a 16 bolt oil pan from the earlier 4.3 does not interchange. Crankshafts manufactured for the 1999 model year (to the end of 4.3L production) had a pilot hole depth of 1.410" when coupled to the LSx-based 4L60E, which had a redesigned torque converter pilot hub which is longer). The torque converter pilot hub is longer than the early 4L60E (similar in appearance to the 700R4 c. 1993-95) or the second generation variants (incorporating a removable bellhousing) with the GMT330 or 1996-2000 C/K series. This engine came in two versions, the LF6 rated at 175 hp (130 kW) - 180 hp (130 kW), and the L35 rated at 180 - 200 hp (150 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.[WIKI]

SIZES COMPATABILITY ENGINE TEMP HEAD TEMP CRANK TEMP NOTES
4.3 OHV 96-98 ASTRO SAFARI BALZER S10 JIMMY SONOMA 1500
96-99 VAN
97-98 HOMBRE
4.3A 4.3B ***** LF6
NOTE 4X2 OR 4X4
4.3 OHV 99 ASTRO BLAZER JIMMY ENVOY HOMBRE SAFARI 1500
99-00 VAN
4.3B 4.3B ***** LF6
4.3 OHV 00 ASTRO BLAZER JIMMY SAFARI S10 SONOMA 1500 HOMBRE ENVOY 4.3C 4.3C ***** LF6
4.3 OHV 01 ASTRO BLAZER BRAVADA S10 SAFARI SONOMA
01-02 1500
4.3F 4.3C ***** LF6
4.3 OHV 01-02 VAN 4.3E 4.3C ***** LF6
4.3 OHV 02 BLAZER JIMMY S10 SAFARI ASTRO SONOMA 4.3D 4.3C ***** LF6

LISTING TEMPLATES LU3 L35

2002 saw major changes to the 4.3L fuel-injection system. For 2002 California emission Chevrolet Astros, GMC Safaris, Chevrolet Silverados and GMC Sierras all came equipped with the updated LU3 4.3L. 2003 saw the L35 discontinued and the LU3 replacing it in all other applications. A new variation was also introduced in 2003, the LG3. For 2004 to 2009 the LU3 has been the only 4.3L 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 1996-01 CPI injector/spider assembly since the poppet valves have been known to stick open. 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.[6] 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.[6] The LG3 was used in Chevrolet and GMC S-series 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 (130 kW) and 245 lb·ft (332 N·m) of torque. The LU3 was rated at 190-200 hp and 250–260 lb·ft of torque. For the 2007+ GMT900 Silverado/Sierra trucks, the LU3 engine received a distributorless ignition system.[WIKI]

SIZES COMPATABILITY ENGINE TEMP HEAD TEMP CRANK TEMP NOTES
4.3 OHV 03-05 ASTRO SAFARI BLAZER JIMMY
03-04 SONOMA S10
03-07 FULL SIZE VAN 1500
4.3E 4.3C ***** DISTRIBUTOR
4.3 OHV 07-12 1500
08-11 VAN
4.3A 4.3C ***** COIL PACK

VALVE INFORMATION

MAKE MODEL YEAR RANGE
BUICK ROADMASTER 1994-1996
CADILLAC ESCALADE 1999-2000
CADILLAC FLEETWOOD 1994-1996
CHEVROLET CORVETTE 1994-1996
CHEVROLET/GMC ASTRO/SAFARI 1996-2005
CHEVROLET/GMC BLAZER/JIMMY 1996-2005
CHEVROLET/GMC 1500 1996-1999
CHEVROLET/GMC 2500 1996-2000
CHEVROLET/GMC 3500 1996-2000
CHEVROLET SUBURBAN 1996-2000
CHEVROLET/GMC TAHOE YUKON 1996-2000
CHEVROLET/GMC EXPRESS/SAVANA 1996-2014
CHEVROLET IMPALA 1994-1996
CHEVROLET/GMC S10 SONOMA HOMBRE 1996-2004
PONTIAC FIREBIRD CAMARO 1994-1997
TYPE HEAD DIAMETER STEM DIAMETER O.A.L. GROOVES LOCATION
EXHAUST 38.1 8.7 125 1 *GM43AU
INTAKE 49.3 8.7 124 1 *GM43AU

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