I'm TRYING to get my timing within 2 and 3 degrees retarded for the NOS set-up. Every time I disconnect the brown/ black striped wire, I time the car as normal and plug it back in>>>it goes back to where it was before....like 5 degrees advanced!!! As you know, I can't have it advanced so much when on the bottle. So, is there a particular sequence or order on which to disconnect and re-connect the harness. I start the car, unplug the wire, time it, plug wire back in and shut car off. I start it up again and check timing....back to 5 deg. advanced again instead of 2 retarded where I set it. Can someone help please???

 

Unplug the wire before you start the car.

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'93 2wd truck
408 sb, vortecs, 454 TBI, Comp Cam, dual exhaust

 

Let me make sure I understand you correctly. You disconnected the wire, set the timing, and then reconnected the wire. Checking the timing with the wire connected it's back to where it was before right? If that's what you're saying, it's normal. The computer wants certain advance at specific times. Altering the base timing only affects the maximum advance at high rpm / throttle I believe. At idle unless you really alter the base timing, it should always be right around the same.