spark plug color, help
 

Spark plugs on 78SC look white and powerdery. I think the car is running lean. Will someone verify that? I tried doing a search, but have not found anything in the forum, technical articles, nor 101 projects.

Could be.....could also be (heat related) incorrect plugs. The PO had W5DC's in mine, I went with the W8DC's to better handle the heat.

Sounds lean, all right. Are you unsure about the color diagnosis? Can you send pictures?

Someone may have it online. But if you want a good illustration, usually the Hayne's manual has a very nice page with color pictures of plugs of all conditions. You can compare their 'lean' one to yours.

edit: Just did a search. Does this help?

http://www.atlanticjetsports.com/_techtalk/00000005.htm

As you see, some light gray is ok.

George

Stealthn, the PO had W8CD and I'm planning to use WR8CD W. Do you think WR8CD W is o.k.?

Aigel, thanks for the reference. I must have the cheap Hayne's manual, because 101 suggested to look there too, but no pics. Thanks for the link. The plugs are normal with a slight amount of deposits on one or two of the plugs.

Plug reading has become more difficult with the advent of unleaded gasoline. It seems to make the plugs *look* leaner than they really are.
The old pictures in various shop manuals of plug colorations, aren't as useful as they once were.

More important than the color, is what you actually see on the tip....
Get a magnifying glass and look at the tip. If the tip has any glazed (shiny) spots, or pebbled texture, the plug is too hot. If you see any metallic particles on the tip, that is metal transfer (from the piston), and the plug is *definitely* too hot.

Race tuners also use the magnifier to look down at the base of the tip, to see other mixture indications. They know what to expect considering the fuels they are using. Art as well as science.

I once watched a World Superbike mechanic read plugs from Ducati racer. He showed it to me, and I commented at how very lean it looked. He laughed and said, "Just right!".

The plugs on your SC shouldn't look any different than on your BMW.


Joe

Safest bet is to go to someone with an analyzer, it will tell you for sure right away...

I'm not familar with the WR8CD?

The haines manual I have has the pic on the inside of the back cover.

It seems, in reading sparkplugs, that the operating circumstances when the engine was shut down would be the most important thing? ie. if they're read right after a cold run wouldn't plugs always look rich ? (at least for CIS which is designed to run rich for the first few minutes)