Which Spark plugs to use?

[Mudhog1974classic]

Hi Guy's,

I'm about to change the plug's on the Mudhog and was wondering what others are running. The Hog's set up is as follow's:

3.9 V8 motor out of a 1996 Disco
Classic front engine cover
SU carbs with custom air box
8mm eagle HT leads
1996 Disco Electronic ignition
Lpg and Petrol

I have been running NGK BPR 5ES-11 and the truck has had a miss on Lpg down low in the rev range under load!

Petrol has been fine.

[discopete]

For both my lpg vehicles I use NGK Iridiums. Get them when they are 20% at sale time. I had a similar problem with the miss when using V-groove ngk changed to iridium and problem masked for a bit. Eventually found cracked rotor.

Pete

[Reads90]

Champion are the ones land rover use. Remeber that the engine you are putting them in is from the 60's so new arty farty spark plugs as the v8's don't like them

[chazza]

Champion are the ones land rover use. Remeber that the engine you are putting them in is from the 60's so new arty farty spark plugs as the v8's don't like them

I have had heaps of Champions fail on me before the service interval is up!

Since changing to NGK Iridums and Gasmaster HT leads, no misfiring at all and what appears to be better economy.

[Blknight.aus]

I like the NKG range, the iridiums I think are a little much but the do last well if your engines on tune...

[discopete]

Just remembered, I used 1 plug colder for lpg which is bpr6 range. That's the norm when running lpg and if not using iridium plugs, which don't ever need gap adjusting, close the gap a bit.

Pete

[Mudhog1974classic]

Thanks Discopete,

I think I might try the Iridium plugs, will look for stockest tomorrow and order some.

Thanks for the info everyone that helped

Cheers
Brett

[LOVEMYRANGIE]

The 1.1mm plug gap might be a little too big as std gap is only 0.8mm. You will get a better flash using smaller gap.
I run a std 3.9 on dinojuice and ditched the resistor plugs in favour of your std NGK BP5ES plugs and KV85 Magnacor leads.
Iridium plugs will give you a longer life and an emptier wallet, but performance wise it wont increase anything.

There are some people who are 'excited' by the Bosch Super 4 range of plugs. Again, not so much of a performance increase, but technically they are better due to 4 ground electrodes positioned horizontally increasing exposure the spark gets compared to a normal plug. Bosch pt # WR91

[Tombie]

Super 4 plugs quench the flame front and are crap.

Iridiums dont soot up on the 3.9s and work the best.

Champion - Never had a vehicle running champions that didnt have issues.

[LOVEMYRANGIE]

Super 4 plugs quench the flame front and are crap.

How do they quench it? The spark is fully exposed??