As some of ya'll may know, I've been trying to get the motor in my Suburban tuned up and working at peak efficiency. Over the weekend I replaced the coolant temp sensor that wasn't working and replaced all the spark plugs with Autolite Platinums. Now after I buy and drop the hotter Accel or MSD coil in, I should be good to go. So, now to adjust the timing...

Referring to this thread: http://www.gmtruckclub.com/forum/showthread.php?t=14855 I have been trying to do a tuneup/performance mod that should yield better mpg and power. The spec for the plug gapping was .035", however, the plugs came from the store gapped at .045" and I thought that would be a good starting point to widen the gap. At idle it seems to run well so far, no missing or anything, most likely due to replacing the plug that had chipped porcelin on the insulator (one of the previously dead cylinders). So, I'm going to drop a MSD or Accel high-volt coil in to make sure the spark can easily jump the gap and then I want to bump the timing. Well, I'm not quite sure how I can do it and find the butter zone easily. I know with older carb'd motors you hooked a vacuum gauge up to the intake vacuum and adjusted the timing and carb until you got the highest readings. However, this is a Throttle-body injection intake system, so it's half-carb half fuel injected.... I don't know where to start. So, how can I evaulate how close I am to getting it right while it's idleing in the driveway. I'd like to avoid having detonation when I'm trying to accelerate on the interstate


PS: What does pinging/spark knock/ detonation sound like? I've never heard it before as far as I know, and I would hope it's not loud enough to hear while driving...