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Last summer, I noticed I had some pinging under load (up a gentle hill in 4th or 5th gear) while driving home from a show in Rochester. When I checked my timing the next day, it was dead on what I last set it to in the early Spring. Took it out for a drive, similar temperature and humidity, no problems at all. Not long after that, I started noticing that my idle was occasionally high at stop lights. Not much, just a couple hundred rpm. I figured something was sticking, so when it happened once when I was parking anyway, I jiggled various carburetor, throttle, and choke pieces, but no change. I figured I'd do another minor tune-up, so when I went to do that and was letting the car warm up, I heard the rpm jump a little by itself, and after a few minutes it dropped back down. I can't remember for sure, but there may have been a "tick" sound when it happened. It was definitely an abrupt change, it wasn't gradual. What I have: Stock engine internals Header Open-style air cleaner SU's MSD6A Pertronix igniter w/flamethrower coil Pretty new distributor cap, rotor, and wires Rebuilt distributor approx. 2 years old NGK BP6ES(?) plugs The only recent changes made to anything are the open air cleaner (custom modified stock housing) and some new Hella horns. I do think I have a small amount of throttle shaft air leakage. The distributor was purchased from Z Car Source (i think) and I tried checking the vacuum advance and it doesn't seem to stick, but I'm not sure how to do an accurate/thorough check. The MSD is about 3 years old, and I've had the pertronix and coil for about 10 years, and they've been rock solid except for when one of the magnets came loose in the pertonix setup. Alternator is also about 10 years old. I once had a wiring harness issue (corrosion) where the regulator(?) hooks in and I had to "jump" one wire across the plastic harness connector so that the voltage gauge wasn't getting pegged. I'm considering trying to source another rebuilt distributor to rule that out. I've also considered I may have an overall low-voltage situation (dimming lights etc.) and may need to get one of those 80(?) amp alternator setups. Anyone else have any helpful suggestions? Am I overlooking something obvious? I'd like to get some leads on this before I take her out for the Spring Thanks all!

I've had no problem in the past setting the ignition timing on few different L6 motors, various 240z/280z style timing marks, etc. so I'm kind of stumped on what's happening. Quick overview: this motor was actually built by another owner, I bought it and had it crated over, dropped it in to replace my dead blow through set up. I was told the specs for it, complete bottom rebuild/head/cam setup to my liking. Crank pulley that came with the motor is a single groove, I can't tell if it's the euro version (the ring portion looks different), and doesn't seem to match any aftermarket pulleys either, so confused here as well. There are multiple grooves / timing marks on the pulley, which look like this: - Big gaps are increments of 10 degrees (verified with 280z timing scale tab), smaller gaps are increments of 5 degrees - I checked for TDC via spark plug on #1 on compression stroke, it was the highest at the black "0" mark on the pulley, farthest to the left if looking from the front - When I go to set the total advance timing at 3k+ rpm, it looks like the above pic.... which shows the supposed 35 degree offset mark based on the established TDC, way off from the timing marker/pointer, it's reading almost 10 degrees full advance which is not correct. Note at this setting, the motor runs very healthy. - I've tried adjusting to the referenced black 35 mark to coincide with the black 0 TDC mark at full advance: loss of power and heard detonation. - The red numbers are what makes more sense to me, as I think the total advance is already correct, but that doesn't jive with what I saw to be TDC (the #1 piston was higher on the stroke on the black 0, vs red 0 mark) I'm just running it as is right now, but would like to find out once and for all what's really going on here.. any feedback is appreciated. Power level is great, also getting a lot of exhaust popping when I let off (though the afr is fine) which I'm not sure is related to the ignition timing or not. Pic of the crank pulley: