17 sets of spark plugs in 9 months

[lux]

hello fellow rover lovers, I have a problem with my disco and I was wondering if anyone else has had and possably resolved a similar issue.

I have killed 17 sets of spark plugs in 9 months (a set aprox every 1000klms) they carbon up and stop producing spark, even after a clean they still no longer work, (plugs end up covered in a layer of black carbon)

I have tried NGK, DENSO, and BOSCH,(with gap of aprox 0.90mm with all)

I have replaced the coil, leads, distributer, distributer module, distributer cap, air filter and had the air/fuel mixture set by a land rover service department.. the coil reads 12.4 volts at the - and +, and I have done a compression test(incase of rings or valve leak) and they tested 175-180psi per cylinder, I have set timing and had it checked.

(although some of the above replacements probably werent nesessary in relevance to the issue.. im desperate)

1993 Land Rover Discovery (pre apr-93) 3.5L v8i(stock)215,000klms on clock, auto, consistantly serviced.

Any advice will be valued and appreciated, Thanks.

[Les Henson]

If it'a wet carbon deposit it's likely to be burning oil. Dry could be excessive fuel. Does your engine smoke ? Either just on start up (valve stem seals or guides)or when you briefly rev the engine (valve stem seals), or all the time (rings)?

Having said that, your compression reading seem fine to me.

Les

[imspanners]

As Les said above, oil deposits,

Or do you do a lot of town driving (short runs, stop/start)?

If so try hotter running plugs in the case of NGK try BPR4ES (if I remember correctly)

useful spark plug info