Plugs and Leads for LPG

[xtreme patrol]

Hey Patrolers

Im going to replace my leads and plugs because im still getting some backfiring when on gas is there a special type of plug or leads i need for LPG or will some normal bosch platinum plugs suffice?
what about the leads ive read somewhere that 8mm spiral are the go for gas

Anyone able to give advice?

Cheers
Darren

[the evil twin]

spiral leads and platinum plugs (one range colder I think but not sure on that bit). certainly make a diff on teh TB42 EFI's so should be the go on the 45's as well I reckon

[ute351]

the evil twin is correct. The spark plug gap needs to be reduced 0.1-0.2mm and needs to be one heat range colder. For Bosch plugs, the colder plug's part number is numerically lower, where NGK plugs the colder plug's part number is numerically higher (just to confuse you). For my dual fuel GQ (4.2), the standard Bosch plug is WR8DCX+, but i use WR7DCX+ plugs with a reduced gap. Check the Bosch website to help understand this and choose the right plugs, the section at the beginning explains all this:

http://www.bosch.com.au/content/language1/downloads/Spark_Plug_Australia_Web.pdf

[da' maverick]

have you got 'em yet. if not ill try and get you some at trade price .

[greynomad]

I have owned LPG cars for many years including a taxi, all falcons. Also have a Courier 2.6 MPI on gas as well. If the engine is working hard go one heat range colder. Replace the plug leads at or before 80k. (Old leads cause ignition coil and module failures) Set the plug gaps approx 25thou. Just use ordinary replacement plugs. If you are a tightarse you can extend the life by filing the centre electrode square when the edges are rounded. Expensive plugs don't seem to work any better than the ordinary ones. Replace at 40k. Make sure that you replace the lead from the coil to the distributor. Check your idle mix on the converter as well. Don't forget that LPG has a slower VOD and the timing has to be recalibrated. Approx 10deg advance over petrol at idle and to 1500rpm, max advance at 3000rpm. LPG has a higher octane rating 130 and can run at a much higher compression ratio. Timing problems show as >10% LPG consumption over petrol. If you want more info please email me.

[timbar]

I have owned LPG cars for many years including a taxi, all falcons. Also have a Courier 2.6 MPI on gas as well. If the engine is working hard go one heat range colder. Replace the plug leads at or before 80k. (Old leads cause ignition coil and module failures) Set the plug gaps approx 25thou. Just use ordinary replacement plugs. If you are a tightarse you can extend the life by filing the centre electrode square when the edges are rounded. Expensive plugs don't seem to work any better than the ordinary ones. Replace at 40k. Make sure that you replace the lead from the coil to the distributor. Check your idle mix on the converter as well. Don't forget that LPG has a slower VOD and the timing has to be recalibrated. Approx 10deg advance over petrol at idle and to 1500rpm, max advance at 3000rpm. LPG has a higher octane rating 130 and can run at a much higher compression ratio. Timing problems show as >10% LPG consumption over petrol. If you want more info please email me.

Sounds pretty much spot on to me

[xtreme patrol]

I have owned LPG cars for many years including a taxi, all falcons. Also have a Courier 2.6 MPI on gas as well. If the engine is working hard go one heat range colder. Replace the plug leads at or before 80k. (Old leads cause ignition coil and module failures) Set the plug gaps approx 25thou. Just use ordinary replacement plugs. If you are a tightarse you can extend the life by filing the centre electrode square when the edges are rounded. Expensive plugs don't seem to work any better than the ordinary ones. Replace at 40k. Make sure that you replace the lead from the coil to the distributor. Check your idle mix on the converter as well. Don't forget that LPG has a slower VOD and the timing has to be recalibrated. Approx 10deg advance over petrol at idle and to 1500rpm, max advance at 3000rpm. LPG has a higher octane rating 130 and can run at a much higher compression ratio. Timing problems show as >10% LPG consumption over petrol. If you want more info please email me.

Thanks graynomad and everyone else too. Still gotta get around to do it yet not enough hours in a day hey

[Silver]

I was going to suggest getting the longer rotor - but your new fangled TB45 wouldn't have anything so old fashioned :-)

Lakes Entrance and Bribie Island. You blokes should be fishing in this weather :-)

[Nobby]

I have owned LPG cars for many years including a taxi, all falcons. Also have a Courier 2.6 MPI on gas as well. If the engine is working hard go one heat range colder. Replace the plug leads at or before 80k. (Old leads cause ignition coil and module failures) Set the plug gaps approx 25thou. Just use ordinary replacement plugs. If you are a tightarse you can extend the life by filing the centre electrode square when the edges are rounded. Expensive plugs don't seem to work any better than the ordinary ones. Replace at 40k. Make sure that you replace the lead from the coil to the distributor. Check your idle mix on the converter as well. Don't forget that LPG has a slower VOD and the timing has to be recalibrated. Approx 10deg advance over petrol at idle and to 1500rpm, max advance at 3000rpm. LPG has a higher octane rating 130 and can run at a much higher compression ratio. Timing problems show as >10% LPG consumption over petrol. If you want more info please email me.

Thanks for this gr8 info. I'm about to a major service and this info will help.

[greynomad]

When you are setting mixture etc make sure that the closed loop O2 sensor and controller computer (if fitted) is set to calibrate gas mixer (shorting or open circuit link) (or have the computer reader for the gas system) otherwise you will be chasing your arse all over the place. If in doubt don't touch the settings or get a gas specialist to do it for you. The gas mixer requires major service or replacement after every 3-6 years or when the cooling system allows it to freeze up. (often in very hot weather heavy loading)