INFO. ON APPEARANCE/MECHANICAL DIFFERENCES (4.3L LB4 ENGINE)

Subject: ENGINE APPEARANCE AND MECHANICAL DIFFERENCES

Model and Year: 1992 S/T C/K AND G TRUCKS WITH 4.3L (LB4) ENGINES

The purpose of this service bulletin is to inform field personnel of the appearance differences and the mechanical differences of the 1992 4.3L LB4 engine, manufactured at Tonawanda, NY vs. Romulus, MI.

TONAWANDA - (LB4) ROMULUS - (LB4) ---------------------------- ---------------------------------- Engine Identification Number Engine Identification Number beginning With "T" located beginning with "W" located on on the front of the engine the front of the engine block at block at deck height in front deck height in front of the cylinder of the right cylinder head. head.

1). Engine painted as 1). Engine painted as an assembly. components; therefore This is the appearance of the aluminum intake previous model years; black manifold will be silver intake manifold and engine block. in color.

2). Net valve lash rocker 2). Adjustable rocker arm studs. arm assembly (new stud, ball, and nut).

3). Camshaft bearing order 3). Camshaft bearing order is the revised to allow engine same as previous years. plant assembly of the Order (front to back): 1,2,3,2 bearings from the rear of the block. New order (front to back): 1,3,2,1 1. Largest outside 1. Largest O.D. diameter 2. Mid Size O.D. 2. Mid Size O.D. 3. Smallest O.D. 3. Smallest O.D.

Note: Both engine plants will use a new camshaft with a smaller lobe base circle and a long travel roller lifter. These were engineered to be compatible with the net valve lash (Tonawanda) feature.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.