I have a 1971 200i6, and when I run wide open, I get a lot of pinging, which I assume is from detonation. The timing is set about 10 degrees above top dead center, should I be running a "colder" or "hotter" plug, and how can I figure out what plug to use?
Higher octane fuel will help a lot with preventing the pings. Back your timing down a couple of degrees at a time until it stops. how to read plugs link:http://www.dragstuff.com/techarticl...park-plugs.html (hint: use new plug, make a WOT run (1/8th or 1/4 mile or so), throw it in neutral after letting off, turn key off. Do NOT idle to a stop (ambigous info at idle). Read the plug. Make a change, put a new plug in, repeat. the information you get off reading the plug will indicate whether or not your too rich/lean or using too hot or cold of a plug. Also, use a magnifying glass if you have it to read the plugs (they make special plug viewers also btw)
I am going to assume that your,"above top dead center" is actually after top dead center....the factory specification is actually 6* before top dead center.....try bringing the timing back closer to TDC. If you can't...your camshaft timing may be off a tooth or two.....
If you are running 10 degrees before TDC you should retard your timing to 6BTDC and retest. Then 2 degree increments till your satisfied.. If you are running 10 after TDC, and are spark knocking, you have timing chain issues.
