Timing gmc, chevy, engines vortec v6 and v8 89 and up.

By distributor settings i have to assume you mean ignition timing?
How many liters? 4.3L V6 timing is set when the distributor is installed. #1 cylinder at TDC, (Top Dead Center) on the compression stroke. There is a easy trick to do this without removing valve covers to watch when both valves are closed on the number one cylinder, Remove the number one spark plug. Have a helper turn the key quickly from run to start and back to run(Make sure the distributor is unplugged and the coil wire is grounded to prevent engine starting!)while you hold your finger over the spark plug hole.(you could also use a compression gauge if you have one.)This is called tapping over the engine.You can feel the compression trying to blow your finger off the hole. Look for the timing mark on the harmonic balancer approaching the pointer on the timing chain cover. Once this is achieved, turn the key off, and rotate the engine by hand with a socket on the crankshaft pulley bolt until the tdc mark lines up with the timing mark on the timing cover. The engine is now set up at #1 tdc on the compression stroke. Look at your distributor, there are three marks on it. An indent on the bottom of driven gear, A mark in between the two shoulders just above the driven gear and when looking down at the top of the distributor a small pointer with the number 6 in it.(Disregard the one with the 8 in it as these distributors are used in the v8 as well Unless you are working on a V8!)Line up the indent with the mark between the shoulders with the rotor installed. The rotor segment should be pointing to the distributor cap hold down screw nearest the flat side of the housing. Using a long screwdriver align the oil pump drive shaft with the slot in the bottom of the driven gear. Holding the shaft in place with the housing and the two bottom marks lined up install the distributor into the engine. The shaft will turn as you engage the camshaft drive gear. With the rotor installed the rotor tip should now be pointing at the 6 mark at the top of the housing when fully seated. If the distributor will not fully seat then the oil pump shaft is not lined up. No worries though, have a helper crank the engine over a few turns, this should allow the distributor to drop in fully. Realign the mark on the balancer with the timing mark on the cover again, using the procedure mentioned above,and make sure the rotor tip points very close to the 6 mark. Rotate the housing until the 6 is dead center with the rotor metal conductor(segment). If it won't line up you installed the distributor a tooth or more off, Try the procedure again. Bolt down the distributor and you're in. If you get a check engine light afterwards and DTC(DiagnosticTrouble Code) P1345 is set off, the distributor in not installed correctly. The VCM( vehicle control module) sets the running timing based on inputs from various engine sensors so there are no other adjustments to make. Good luck stmusgrove, Let me know how it works out!
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