Spark Plug Colour Vitesse

[Swifty75]

Hi All

A quick question relating to a 1970 Vitesse.

I have checked the spark plugs on the car tonight. They are about 3 months old. 5 out of the 6 were quite sooty so this lead me to believe I must be running rich which I can sort. Cylinder 4 was very clean as if it was running lean. I have recently done the valve clearances could  have got one wrong and caused this?

Thanks Neil

[mazfg]

1-3 are on one carb and 4-6 on the other. If 4 is clean and 5 n 6 aren't maybe piston rings are worn allowing oil in, hence blacker. 1-3 adjust the carb for that to make less rich? If in doubt still, do a compression test wet n dry?
Also did you take it out for a good run. Just running on the drive can soot up at idle

[Nick Jones]

Normally 2 & 5 are the leaner ones due to the way the manifold flows.

Possible air leak at the gasket allowing extra air into #4 (bit of a long shot).

How clean is clean?  Really clean like it's hardly been firing might mean just that - or that a small amount of water is finding it's way into that pot from head gasket of manifold water way and steam cleaning it.

Nick

[Swifty75]

Right I have now checked the compression on all cylinders. It is reading 125 - 135 across all 6 so a little bit low, although it runs well. It does not burn oil and the water never needs topping up. I have taken it on some fairly long runs (about 200 miles in one afternoon) and have had no problems. The car is a bit of a mish mash of parts. The block is an ME from a 2000 with HE (high compression) suffix. I have measured the throw on the pistons and it appears to be a 2500. At some point I think it has had some parts from a later TR6 fitted as the brake callipers are post 72 metric unions. As the engine is not a Vitesse engine and could be part 2000 part TR6 it is hard to say what the compression should be?