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MG TD TF 1500 - Color of plugs

I just removed the spark plugs and would like your expert opinion on the color. All plugs are the same, with the insulator light brown, both electrodes gray/brown, and the end of the shell at the bottom of the threads black with dry soot. I have not seen the black soot on the end of the circle formed by the metal shell before and was wondering whether this is OK. It is not loose or thick, but definitely very black and dry in contrast to the other parts which have no black, just light brown or gray/brown. Thanks for your input. Ron
Ron Coates

Hello. That is amazing that someone has an XPAG motor with plugs not melted or dripping with oil or fouled! Seriously, the gray/brown color is perfect for any 4 stroke motor. Whitish indicates too hot and/or lean, and blackish too cold, rich, etc. This color is indicative of the temp of the insulator/electrode as well as mixture strenght- yours sounds perfect. I feel these engines do run a tad rich to run well, which would cause the dry black area. A good old-fashioned parts store should have color pictures of plug appearance- hard to find, but interesting.
George Butz

George is right IMHO. Boadicea (1250cc) tends to run rich and cool. The plugs need cleaning and wire brushing every 3000 miles with the oil change. They tend to have a light coating of soot over grey/brown deposit. If you take the plugs out after she has been idling for a bit, they then are wet with excess fuel, but are alway dry sooty when taken out hot after a good run.

Was suggested to me that a "hotter" plug might be better, also that NGK plugs run cleaner than Champions, but I have never tried. Any suggestions for NGK equivalent types?
Paul J Joachim

Please refer yourself to the article in The Sacred Octagon, Vol 35, No 5, Oct 1997. It has all the info. you will ever need on spark plugs.
I currently use the Champion N5C in our XPGA motor, and found it to be very satisfactory. I have tried the NGK B5ES, but found it to foul more. The best plug I have found is the now obsolute Champion (Made in Eng.)NA8. I still have a set of the original plugs that were in our car when it was built. Even though they are a cooler plug the run better than anything new.
With the N5C, we still get a little sooty condition on the rim of the plug. Most T Cars tend to run a little rich. Every 1000 miles I pull them out for a little sand blast cleaning.
If you use a Lucas Sport coil, as I do, set the gap to .035".
colin stafford

Paul- I agree with the above suggestion- for cars with the 3/4 reach plugs. They would not be a good thing for the earlier TD heads with 1/2" reach! I have used the NGK B6HS (now it has a new #-both are on the box) for years with good results. A couple of TD's and a TF1500 around here do great with the N5C's.
George Butz III

This thread was discussed between 27/08/2000 and 06/09/2000

MG TD TF 1500 index

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