spark plug gap

[digisol]

I guess most anyone would call .1 a small amount, if so then yes, it can go smaller, but set it to a well measured 1.5 and (with all other things correct, (not worn, broken, adjusted incorectly, or otherwise not running properly, and it will run better.

But heh, to each their own, go set your trusty commodore at 1.3mm or less (on std unleaded petrol) and see how ya go, would be good for a laugh, Perhaps another language might do ? I did say (that is with all other things being correct.) if it loses something in the translation please advise what language you require.

 

[Immortality]

I guess most anyone would call .1 a small amount, if so then yes, it can go smaller, but set it to a well measured 1.5 and (with all other things correct, (not worn, broken, adjusted incorectly, or otherwise not running properly, and it will run better.

But heh, to each their own, go set your trusty commodore at 1.3mm or less (on std unleaded petrol) and see how ya go, would be good for a laugh, Perhaps another language might do ? I did say (that is with all other things being correct.) if it loses something in the translation please advise what language you require.

0.1mm is a small gap by most peoples standards, however, i never ever stated to go smaller then 1.5mm other then to stay within factory spec settings as i mentioned in my previous thread. your the one suggesting people set a gap bigger then re-commended. for the record, the very first set of plugs i ever put in my VN were 1.3mm as stated in the NGK catalogue as the sticker on my strut tower was missing. car ran fine other then loosing some fuel mileage. re-gapped to 1.5mm and fuel mileage came back.

1.5mm is the stock gap, but always make it a slightly loose fitting 1.5 so the feeler gauges go in fairly easy, A tight 1.5 might be in reality 1.3 mm - 1.4 mm
doing as you suggested "loose" 1.5mm could easily result in a gap that could cause a misfire when under load. learn to use feeler gauges is all i can say to you.

 

[hako]

But heh, to each their own, go set your trusty commodore at 1.3mm or less (on std unleaded petrol) and see how ya go, would be good for a laugh, .

Well here's a laugh: 5 years ago when I bought my Commodore one of the first thing I did was replace the plugs and leads. I set the plugs to 1.0mm for a number of reasons which don't matter. 5 years and 100,000km later and the plugs have never been removed/replaced or checked and the car runs as smooth and hard as it ever did. I run on E10 or unleaded - whatever is the cheapest and never had injector problems plus I use homebrand/cheapest oil with absolutely no problems. I may be in my 60's but trust me, I don't drive like a granny.
This works for me and whatever suits anybody else is OK by me.:thumbsup:

 

[delcowizzid]

factory LPG gap is 1.4mm but i allways gap them at 1.5mm anyway stops the airbox from exploding when they are too small you get spark on both plugs that are connected to the one coilpack causing there to be less spark at the plug that should be firing and causeing the backfire through the intake cause the extra plug is firing the intake charge boom.i have lost count on the amount of lpg commis ive stopped backfiring from just opening the plugs back up from the rediculously small gaps they had so many people still gap the commodores to 0.030 like the old days way too small for wasted spark commodores fuel consumption skyrockets anything much under 1.5mm as well.

 

[vxcalais_01]

On gas the recommendation is 1.0 or 1.1mm otherwise you can get misfiring or crossfiring - this is due to the gas mixture having a higher electrical resistance than a petrol mixture making it harder for the spark to jump the gap.

You wont get crossfiring, but yes can make it harder. But if you get the 1.5 to work it is much better with the bigger spark. Smaller spark on LPG will reduce chances of back fire, improved ignitability, but you can lose on power.

 

[greenacc]

Anyone got Any ideas why the Magnecor leads sales rep told me to set my gap to 1.2mm? And Hako , after 5 years your plugs would have decayed a fair bit so your gap is probably back out to 1.5mm by now

 

[vxcalais_01]

Why would u keep plugs for 5 years ? unless you did 5000k's in that time. If Holden say 1.5, its 1.5. I have spoken to Ice Ignition on a few occasions, and they only say gap accordingly, which means, whatever is required. You can lose power with a smaller gap, as the spark duration is reduced. Biggest spark possible is the best way, and only reduce when you start getting issues. This could also mean other ignition items are wearing. Try to get some NGK V Groove plugs as they are meant to produce a better spark for the same price. I have also been told to use non resistor which i havent been brave enough to do, as they produce a better, stronger spark. On standard and LPG i have also been told not to go colder as standard are cold enough already and are prone to fouling, poor running when running on petrol. This is confirmed by NGK themselves on their websites. Same as Bosch.

Someone on there or the other forum was gonna try the Atomic plugs. They may be the new wave in the future.

 

[digisol]

Courtesy of;

Top Gun - Products

Experience has shown that LP gas engines are hard on ignition leads. LP Gas in particular operates at a significantly higher arc strike voltage and substantially hotter operating conditions than conventional fuels. LP Gas engines need that to allow more spark power to ignite the fuel mixture.

 

[vxcalais_01]

Courtesy of;

Top Gun - Products

Experience has shown that LP gas engines are hard on ignition leads. LP Gas in particular operates at a significantly higher arc strike voltage and substantially hotter operating conditions than conventional fuels. LP Gas engines need that to allow more spark power to ignite the fuel mixture.

LPG leads are stainless steel with a reduced resistance, therefore helps produce a stronger spark. Best thing to use is standard or lightly larger gap with a spark booster.

 

[digisol]

Hallelujah brother, LPG leads are stainless steel with a reduced resistance, therefore helps produce a stronger spark. Best thing to use is standard or lightly larger gap with a spark booster.

Imortality, if your going to quote something I have written at least quote the entire passage in it's original form and not in your own interpretation for whatever reason.

I guess that some people with limited or virtually nil mechanical knowledge might perhaps interpret a "loose" 1.5mm and having a .010" gap either side of the 1.5 feeler gauge, unfortunately that's not the case and anyone with basic mechanical knowledge might already know the difference between an easy "loose" sliding 1.5 mm and a tight (where the electrode is under tension) 1.5 that could be in reality 1.3 mm, or perhaps it's just a waste of time trying to explain how to use a feeler gauge properly especially to those "google" mechanics who might find it difficult.

Those who regularly gap the rockers on their solid profile cams will / should know the difference between a tight .012" exhaust and a tight .008" inlet that in reality is a bare .008 & .006" or smaller rocker clearance and the difference it makes to performance having either adjusted incorrectly "tight" is no different to plug gap, perhaps more so with the flex in the electrode.

I hope this helps those not understanding what I meant by a tight 1.5 where it is likely to be only 1.3 +/- and that a properly measured 1.5 is just that, 1.5 mm if done properly.

I hope this brings certain clarity to correct spark plug gap, and perhaps why some still have a lousy idle even with new plugs, but there will be some that know exactly what I meant in trying to explain regarding a "tight" or "loose" / easy sliding measured spark plug gap.

I hope this helps a little, and to fill the gap so to speak.