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Chat Area => General Car Chat => Topic started by: JamesV6CDX on 22 June 2009, 13:30:40

Title: LPG Spark Plugs
Post by: JamesV6CDX on 22 June 2009, 13:30:40
For the LPG'ers out there.

Do you use the standard VX twin plugs - or, single electrode plugs? If the latter, do you decrease the plug gap by 20% to .8mm on LPG?
Title: Re: LPG Spark Plugs
Post by: Kevin Wood on 22 June 2009, 15:08:52
I have the GM 4 electrode ones at the moment. They have done 40k (about 14 of which on LPG) and are still fine. I will change them soon, though.

Tempted to put in some conventional plugs a grade cooler and gapped a little tighter than normal just in case but the GM ones appear to work just fine.

Kevin
Title: Re: LPG Spark Plugs
Post by: wingman on 22 June 2009, 15:27:18
As per Kevin I use the GM 4 electrode ones and have had no problems. Was advised by LPG installer to change at 2 year intervals though rather than VX standard of 4.
Title: Re: LPG Spark Plugs
Post by: Lazydocker on 22 June 2009, 15:34:19
As above... Mine have done 24K, 17 of which on LPG.  am planning to change them soon though as I fear they may be past their best ::) ::)

No problems though :y :y :y
Title: Re: LPG Spark Plugs
Post by: feeutfo on 22 June 2009, 15:40:03
4electrode gm in mine prior to install. Didnt gap them just wacked em in.  Runs fine on lpg once fitted. Not even looked at plugs since. Didnt think more than one electrode plugs should have the gap altered. Fit as is?....afaik?
Title: Re: LPG Spark Plugs
Post by: feeutfo on 22 June 2009, 15:54:32
my thinking 4 electrodes share the same amount of juice from the coil pack. So therefore last or ware longer. But not sure if 4 electrodes shield the spark a little?as i beleive Mark dtm suggest, i think?
Title: Re: LPG Spark Plugs
Post by: TheBoy on 22 June 2009, 16:08:18
I though the cencensous was the 4 electrode may guard the spark too much, and just twin and replacing them regular was the usual recommendation?
Title: Re: LPG Spark Plugs
Post by: Kevin Wood on 22 June 2009, 17:07:06
I think the 4 electrode / 2 electrode debate is the same regardless of fuel type. Only advantage of 4 electrodes is that they get eroded slower hence the 80k service interval. They just happen to be what I put in mine way back when I bought it, and I didn't remember to change them with the LPG conversion.

You shouldn't adjust the gap on either the 2 or 4 electrodes.

I figure with a conventional single electrode plug you can close the gap and also it's easier to find an equivalent plug that's a tad cooler. Not that there appears to be a problem at the moment, but closing the gap a little will reduce the voltage across the plug on LPG and hopefully give the coils an easier life.

I've also scored some suitable Champion double copper for a quid a piece so might well give them a go.

Kevin
Title: Re: LPG Spark Plugs
Post by: Lazydocker on 22 June 2009, 17:16:59
Quote
I think the 4 electrode / 2 electrode debate is the same regardless of fuel type. Only advantage of 4 electrodes is that they get eroded slower hence the 80k service interval. They just happen to be what I put in mine way back when I bought it, and I didn't remember to change them with the LPG conversion.

You shouldn't adjust the gap on either the 2 or 4 electrodes.

I figure with a conventional single electrode plug you can close the gap and also it's easier to find an equivalent plug that's a tad cooler. Not that there appears to be a problem at the moment, but closing the gap a little will reduce the voltage across the plug on LPG and hopefully give the coils an easier life.

I've also scored some suitable Champion double copper for a quid a piece so might well give them a go.

Kevin

By all means give them a go but I don't rate Champion for LPG... Fitted them to the RR and they lasted about 8k :o :o :o NGK were good for 30K +

Just my personal experiences :y :y :y
Title: Re: LPG Spark Plugs
Post by: cem_devecioglu on 23 June 2009, 12:09:05
definitely 4 electrode and NGK..

its been two years I dont touch them.. and idle is perfect and never had problem..
Title: Re: LPG Spark Plugs
Post by: Kevin Wood on 23 June 2009, 12:24:48
Quote
By all means give them a go but I don't rate Champion for LPG... Fitted them to the RR and they lasted about 8k :o :o :o NGK were good for 30K +

Just my personal experiences :y :y :y

Interesting.. What was the failure mode?

Kevin
Title: Re: LPG Spark Plugs
Post by: Lazydocker on 23 June 2009, 14:57:43
Quote
Quote
By all means give them a go but I don't rate Champion for LPG... Fitted them to the RR and they lasted about 8k :o :o :o NGK were good for 30K +

Just my personal experiences :y :y :y

Interesting.. What was the failure mode?

Kevin

Admittedly they were the heat grade for the car and not adjusted to compensate for LPG but they just burnt out... Only way to describe it really. They started missing and, when removed were showing signs of overheating and the electrodes were FUBARed

Stuck in a new set of NGK's without changing anything else and they were still in it when I got rid some 30k later, with no missfires or noticeable wear.
Title: Re: LPG Spark Plugs
Post by: Kevin Wood on 23 June 2009, 16:37:50
Hmm. Might steer clear of them and chuck some more VX 4 electrodes in then. Better the devil you know...

Kevin
Title: Re: LPG Spark Plugs
Post by: JamesV6CDX on 23 June 2009, 16:39:06
Quote
Hmm. Might steer clear of them and chuck some more VX 4 electrodes in then. Better the devil you know...

Kevin

I agree - I have heard bad stories about champion, on LPG......

Title: Re: LPG Spark Plugs
Post by: Lazydocker on 23 June 2009, 18:06:13
Quote
Hmm. Might steer clear of them and chuck some more VX 4 electrodes in then. Better the devil you know...

Kevin

I intend to stick to VX plugs... There's been no noticeable issues with the ones fitted and they're cheap enough on TC :y :y :y

Incidentally, I've noticed a bit of a flat spot on LPG at about 3k so I think my plugs may be past their best :-/ :-/ :-/

No errors showing on the LPG though after nearly 400 hours running :y :y :y