I recently installed a Pertronix distributor and was able to set the static timing at 4 degrees BTDC. The car starts and runs well without any apparent detonation. The plugs however are black with a very small bit of white showing at the center electrode and the underside of the ground electrode. The car when hot seems to load up and the idle decreases and will eventually stall. I'm assuming that the problem is with fuel mixture and have turned in the jet adjusting nuts a quarter of a turn. At the same time I would like to check the timing with a strobe. My strobe is the older variety without an advance mechanism. The literature I have states that at 4 degrees from TDC the hole in the pulley is 1/8" or 3/16" counterclockwise before the pointer depending on which page you're looking at. It also states that at 400-600 RPM, timing is also at 4 degrees before TDC. Since my car will not idle at that speed and is more comfortable at 700-750 RPM what is the advance at that speed? I can't seem to find information of full advance for a TR3 and am not sure that the Pertronix distributor has the same advance as the original mechanical distributor. I've read that 15 degrees is used for timing with a modern strobe but I don't know what RPM is used at that reading. Timing with a strobe is difficult anyway since there is much in the way in order to point the light accurately and guessing how far the mark on the pulley is advanced from the pointer is not very accurate. I'm guessing with an older strobe the mark should be somewhere between 3/8"- 1/2" from the pointer at 15 degrees BTDC (but at what RPM?). I know investing in a more modern strobe would be helpful and I plan on it. They certainly are cheap enough. Any help would be appreciated.