Fouling plugs

[allanbennett]

Any ideas? The photo shows a brand new plug which has done 30-40 miles only. I reckon the car is getting way too much fuel and not burning it all, hence the build-up, but am I on the right track with this? I also get some bluey-white exhaust smoke when I pile on the revs and the car is horrible to drive at low revs, eg taking away from lights etc. Once I get up to 2000 revs plus it runs very well and very evenly - again adding to my theory that at low revs there's too much fuel around not being used, whilst at higher revs it's much sweeter.

Any thoughts? Thank you...

Allan.

[loudnproud]

imported post

If it was running too rich you would have a sooty plug your photo shows lots of oil on plug threads and what looks like a build up of burnt oil on the electrodes are you using the correct grade of plug?.

Peter

[Thurlo Squire]

imported post

Hi Allan

Sounds and looks like you are burning oil. How worn is the engine? Have you done a compression test? May be valve stem seals are shot?

Nigel

[GDPR]

imported post

That centre electrode looks a bit short - can you find a set of N12Ys?

I would agree that there is likely a bit too much oil kicking around in that cylinder but a hotter plug should take longer to foul up so if you can find some 12Ys it may help.

That rubbish low speed running is probably because the engine is breathing a bit hard from the crankcase straight into the carbs due to worn bores - that would tie up with the light coloured exhaust smoke - see if you get a jet of fumes from the cam cover pipe when you pull off the breather pipe with the engine running, and if the revs rise appreciably.....

Russ:dude:

[allanbennett]

imported post

Thanks for this guys. The engine had a bottom-end rebuild about 4000miles ago, with new pistons, rings etc and I'm reasonably happy that's all ok - however, the heads were left alone at that point and, although I've had the car 12 years, I've no idea whether they've ever been re-worked. The mileage is 86,000, so I suppose if the heads are original they'll be about ready for a decoke and a sort out of the valves.
Shame, really, as there's no spare cash at the moment, so if my problem DOES turn out to be valve-stem seals, then I'll have to take the tax off and write off this summer.