I’ve done the mod, conservatively. I installed the high output coil. I gaped some plain copper plugs at .050 and advanced the timing to 12.5 +/-. I notice a little bit of extra… extra. My question is is there a measurable “correct” that I can use to know I’ve got it right such as RPM measurement or some such? Maybe a chart pertaining to how much to advance based on given variable? I’m not wanting to go back, I just want to do it correctly.

 

You removed the spout plug to disable computer advance when setting the base timing? If not you did it wrong and it's way off of where it should be.

 

i did. I removed the spout.

It runs well, just differently. I don’t know a very many things about internal combustion engines. I do know people who are so in tune with a vehicle that they can tell by the sound of the engine if something is wrong and as much as I hope to make it to that point, right now I am at a competency level that requires more empirical data, unfortunately. I very much want to do right by this truck, I don’t have a terrific track record with vehicles and my goal with this make and model was to go in a positive direction. In fact, my goal with this mod was not really an increase in power for powers sake, I’m trying to achieve a more complete combustion of fuel to cut down on carbon residue to extend the life of the engine. I really want to restore the performance of the fuel system to new stock which I believe to be approximately 16 MPG. To that end I have replaced nearly the entire fuel delivery system, tank, sending unit, line, pump, filter, regulator, and injectors. I’m also working piecemeal on the emissions and exhaust components as well and as needed. The catalytic converter down was in the bed of the truck at the time of purchase and it was to my surprise and dismay that it failed to start on the first attempt after I got it home. I kinda like to think I’ve nursed it back to relative health over the last four months. Anyway, I’m new to this and trying my best and very much would appreciate some guidance. That’s why I’m here and asking, humble in my ignorance.

 

OK so what you did with that adjustment is set the base timing slightly advanced from the factory spec... which is 10deg BTDC. The computer adjusts timing from that base in real time many times a second depending on a whole bunch of factors, and the only indication you will have that something isn't right is poor performance or audible detonation. There is no way to correctly adjust timing on this system by ear, computer precision require a technically accurate base setting, after that you just have to trust that the system will do a better job than any system created up to that date.

 

Yes, 10 degrees on the strobe light, after the engine is at operating temperature, and SPOUT removed.
There should be the original emissions decal under the hood, and/or decal on the valve cover of the engine that states this.

Not necessarily a chart, but yes, the computer uses 'tables' and 'fox functions' with specific inputs(variables) to output advance.