Engine must have the correct timing so that the air-fuel mixture detonates at precisely the right time.
Developed and produced by General Motors, the 4.3L Vortec was a 4.3-liter V-6 engine used in Chevrolet vehicles. This engine was introduced in 1990 as a replacement for the 2.8-liter V-6. It is based on the bigger 5.7L V-8 GM engine, but has two fewer cylinders. GM engineers have determined precise timing specifications for the 4.3L Vortec.
Timing Definition
Ignition timing is the measurement in degrees of the crankshaft rotation at the instant when the spark plug fires the air fuel mixture while the piston is on its compression stroke.
Adjusting Timing
To set ignition timing on this engine, put the electronic spark timing (EST) in bypass mode by disconnecting the timing connector. This is a tan wire with a black stripe. This timing connector breaks out of the engine wiring harness conduit and is located adjacent to the distributor.
Timing Specification
The ideal time at which the mixture should be fully burned on the 1991 GMC with the 4.3L V-6 is set at 0 degrees of the crankshaft rotation both for the manual and automatic transmissions models.
Tags: timing, specifications, 1991, crankshaft rotation, degrees crankshaft, degrees crankshaft rotation, timing connector
