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Thread: Tappets or Rollers Question
11-15-2013, 05:58 PM #1
Tappets or Rollers Question
My truck is an 07 GMC Sierra Classic with the 4.3L engine, the engine code is LU3. What I need to know is does the engine have hydraulic flat tappets, hydraulic rollers, or balance shaft hydraulic rollers?
Thanx in adavance for any assistance!
11-15-2013, 06:45 PM #2
4.3L (262 CID)
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.
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. 1987 saw new center bolt valve covers and hydraulic roller lifters.
For the 1992 model year, the 4.3L had its block design modified to allow a balance shaft to be installed. 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.
As of the 2013 model year, the 4.3L is 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 are the GMT900 light duty trucks and vans. Commencing with the 2014 model year, a new LV3 EcoTec3 4300 based on the GEN V (LT1) Small Block Chevrolet will become the new base motor for the next generation Chevrolet Silverado/GMC Sierra light duty trucks and will be phased in throughout the rest of the truck/van line after the 2015 model year, which will signal an end to a design dating back to 1955. Like its small block V8 counterparts, GM Powertrain also sells the motor for marine and industrial applications.
Looks like roller lifters were added in '87 and a balance shaft in '92Ray
'09 Avalanche LTZ - Black
'05 Envoy XL (sold)
11-16-2013, 04:08 PM #3
Thanks Ray! Looks like some good research on your part, I appreciate it. Where did you find this information?
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