Spark Plug Query

[Rubens]

In the Q&A workshop section of LRO (Landrover mag) this month, someone is having mpg issues on LPG (3.9 V8 Disco). They have advised he should run plain and simple plugs and nothing flashy like NGK LPG Iridiums. They are exactly what I'm running at the moment in my 4.2 Classic along with Magnecor leads. They were put in at the same time as the conversion so I have nothing to compare them with (when running on LPG) but will say they put a stop to the erratic idle I was getting on petrol before the conversion.

I average 11mpg on gas around town and 19mpg on a run which I think is acceptable on a 20 year old V8. I sometimes think I lack grunt putting my foot down uphill but think my vaccuum advance needs changing.

I'd be interesred to hear other peoples views on this subject. Many thanks.

[billynoband]

My installer always says standard plugs unless it won't run then experiment with flashy ones.

[binder4]

Car ran like a hairy goat on iridium plugs, started playing up after about 20,000k's. LPG mechanic reckoned they "glaze over" with age and missfire, dont use them.
Replaced them with standard NGK's and it runs like a train again.

[Gilbertd]

Both of mine used to run standard NGKs (BPR6ES) but they were only good for around 10,000 miles. I now run the Iridium equivalent (BPR6EiX) and the P38 has run faultlessly for the last 20,000 miles (the LSE has only done about 8k since fitting them). Standard Iridium equivalents are a lot cheaper than the special 'LPG' plugs which appear to differ only in the higher price tag......

[SimonHobson]

I average 11mpg on gas around town and 19mpg on a run which I think is acceptable on a 20 year old V8.

19mpg How the **** do you manage that ? I seem to get about 12.5 no matter what I'm doing - commuting to work, "making progress" down the motorway, or flogging it up Corney Fell.

[Gilbertd]

Dunno how the OP manages it, but that's about identical economy to my 4.2 LSE. You must just have a heavy right foot.......

[SimonHobson]

You must just have a heavy right foot.......

You mean ... there's other positions you can use the throttle between on and off ?

Actually I suspect ignition timing may be an issue, and on my long "round tuit" jobs list is a mappable ignition setup.