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Originally Posted by bracketshark
I know that when my timing was set at the Chevy dealership my friend employed there used the hand held unit and I myself turned the distributor until he said it was on ZERO. If you think the distributor will not affect timing go to one and turn one and see what happens. I've changed a dozen or so intake gaskets on vortec motors and know for sure you better put that distributor back in the exact location it comes from. You are correct in saying the computer will make adjustments as neccessary but it must be at ZERO PLUS OR MINUS TWO DEGREES OF DISTRIBUTOR [/b]TIMING PERIOD or the check engine light will come on until corrected. The engine will run up to 16 degrees out. If you want a real challenge get the GM distributor installation procedure and try to figure IT out, if distributor location didn't matter it wouldn't be so important where it was installed.
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I do have the procedure for setting the dist and it is not hard to figure out.
I have set a few hundred in my time.
And yes the setting mater but it has nothing to do with the ign timing.
http://files.automotiveforums.com/ga...hp?photo=51302
Here is some more info from the repair manual on it.
IGNITION SYSTEM
Enhanced Ignition System
The enhanced ignition system consists of the VCM, distributor, ignition coil driver module, ignition coil and Camshaft Position (CMP) sensor. Ignition control and by-pass functions are controlled by the VCM.
* Camshaft Position (CMP) Sensor
CMP sensor is similar to CKP sensor. CMP sensor provides one pulse (1X signal) per camshaft revolution. VCM uses this signal in conjunction with the crankshaft position to determine which cylinder(s) are misfiring. * Crankshaft Position (CKP) Sensor
CKP sensor is located in the front engine cover. Air gap between sensor and target wheel is preset and is not
adjustable. Target wheel has 4 slots, 60 degrees apart, and is keyed to the crankshaft. Rotation of target wheel creates
a change in the magnetic field of the sensor which results in an induced voltage pulse. One crankshaft revolution will
result in 4 pulses (4X signal). Based on these pulses, VCM is able to determine crankshaft position and engine speed. VCM will then activate the fuel injector and provide spark to distributor.
* Distributor
Distributor assembly contains the Camshaft Position (CMP) sensor, cap, rotor and shaft. A Diagnostic Trouble Code (DTC) will set when distributor is installed a tooth off in
relation to the camshaft. Distributor is not serviceable. * Ignition Coil Driver Module
Module is mounted next to coil. VCM signals the ignition coil driver to turn on primary current to the ignition coil by pulling the IC line high (4 volts). The ignition control
driver turns the primary current on and off by applying and removing ground to primary winding. Module does not have a back-up function that would allow engine to run if IC signal is lost.
Ignition Timing Control
Ignition spark timing and ignition dwell time are entirely
controlled by the PCMNCM. The PCMNCM monitors information from various engine sensors, computes the dissjred spark timing and dwell, and firing of the ignition coil via IC line to the coil driver.