The V8 Owners Forum -

Thinking about renewing the plugs, leads, cap and rotor on my 3.9 range rover.

Apparantly improving ignition system on lpg equipped cars improve economy and performance. lpg very dependant on ignition being in tip top condition.

What plugs are best to use ? (make,heat range grade)

Id love to buy a set of magnecors but there too expensive, what else can i get a little cheaper.

Whats the best ignition timing to run ?

hello mate , i'm running std ignition timing std plugs , aftermarket cap and leads std coil on my old 3.5 efi and it runs a treat on LPG
the only thing i have changed is the ignition module

Been having a few running problems the last couple of days.

Intermittantly my v8 will pop back through the inlet whilst running on gas.

Guessing its ignition related but my coil is new lucas, new bosch plugs cap and rotor look in good condition.

Popping back is usually because it's running too lean. Richen the idle mixture a bit.

I think NGK do plugs specifically for LPG, but they ain't cheap!

Chris.

You say in the ignition post that you run a wideband lambda system.

Where did you get it from mate ? What sort of cash are these and are they difficult to fit.

Have considered fitting a loop control lambda system for the lpg but they aint cheap.

Also seen some vacuum operated mixture control setups from tinley tech much cheaper than lambda control

In my van I've got an Innovate LM1, I have an idea that Bill Shurvington on this forum flogs 'em.
http://www.innovatemotorsports.com/ (that's the manufacturers website).
I got mine for about $340 when I was visiting the USA. A very good bit of kit.
In the Landie I have a Alpha Lambda AFS-1 which is nowhere near as good, but does at least show that things are running OK.
http://www.webcon.co.uk/alpha/lambda_display.htm

Neither are cheap!

Chris.

i have lpg on my 96 4.6 hse V8 r/rover. its brilliant BUT you do need to keep the ignition in tip top and close the spark plug gaps. mine are the standars NGK plugs but gapped to .7mm. i have magnecor leads that made a massive difference when fitted recently.
lpg will eat spark plugs so be ready to change them every 3000 miles, only £20 a set. stear clear of iridium plugs, i tried them and although good to start they went down hill quickly. last year the mot emisions test was a close run thing with iridiums, today with good leads and standard plugs it was soooo good, on lpg and petrol, it was well under the limits.
timing i dont know about, there is no info on moving it on a 4.6 for lpg and theres no distributor anyway.

I've found with all the rover V8 engined vehicles I've ever converted (and I've done a few!) that there are no issues at all if you use genuine leads, NGK BPR6ES plugs gapped to 0.030" and most importantly, GENUINE LUCAS dizzy cap and rotor arm. On the later engines with no dizzy, genuine leads and the same NGK plugs but gapped to 0.035".

Interestingly enough, my Disco II 4.0 which I have just sold was running NGK Irridium plugs - no issues or wear after 30,000 miles. Sort of goes against the comment by redrange, but that's just my personal experience with my own vehicle.

I now have a Chrysler 300c Hemi (5.7 V8), that'll be getting converted soon if I can find the time between customers cars!

badger wrote:I've found with all the rover V8 engined vehicles I've ever converted (and I've done a few!) that there are no issues at all if you use genuine leads, NGK BPR6ES plugs gapped to 0.030"

Interestingly enough, my Disco II 4.0 which I have just sold was running NGK Irridium plugs - no issues or wear after 30,000 miles. Sort of goes against the comment by redrange, but that's just my personal experience with my own vehicle.

0.030 i take it this is 30 thou, whats it in mm
and isnt it strange that a certain product is fine for one aplication but not for another, i didnt get on with iridiums at all, well i did but not for long, strange!!!!!!!!!!!!!

Give or take the nth part of nothing worth bothering about, there's 40 thousandths of an inch (0.040") to one millimetre. 30 thou therefore is 0.75mm.