Spark Plugs

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kiwi
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Spark Plugs

Post by kiwi » Tue Aug 19, 2008 9:30 pm

Interesting debate going on in Trademe forum regarding these things

http://www.trademe.co.nz/Community/Mess ... d=28961243

Going for the more experianced of us BX Forum members which type of spark plug do you prefer?

Who is wrong and who is right about the spark plug gap? Always set mine to 0.6mm in everything except the 2 GTIs I had. Which got a feeling in my current car (need to check gaps) have been set to wide. Even though Haynes recommends Champion and 0.8mm.

Would I be correct in saying a wider Gap causes starting problems?
1991 BX19 TZS 04/01/91 (Deceased)
1990 BX19 TRS 27/10/89 (Reborn)
1992 BX19 TXD (Ex UK - K 744 SDF) 15/06/92
1990 BX19 TZS Auto 06/11/1989
1992 BX TZD Turbo Estate (Ex UK) 1/07/91

jeremy
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Post by jeremy » Tue Aug 19, 2008 9:48 pm

The bigger the gap - the better the starting - in theory. Get the mixture in there - nice big spark and off you go.

The problems are:

Has the system got enough guts to power it. If not you'll get misfires. Electronic systems tend to be better than old systems with points and give a smaller percentage of misfires.

When it fails to start and the plugs are soaked in fuel - a smaller gap may help - why? The bigger the gap the higher the voltage required to jump the gap - and the better the insulation must be to insulate at that voltage. Soaking in petrol isn't going to improve the insulation and so the plugs may not spark! This is probably the very old mechanics trick of getting a car to start by rubbing an ordinary pencil over the plug points. The graphite deposit probably had the effect of narrowing the gap slightly allowing the spark to jump.

kiwi
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Post by kiwi » Tue Aug 19, 2008 10:01 pm

ahh yes the fog of time I forgot that logic. Somehow I was thinking narrower gap would widen over the period between services. Dont ask me why I was thinking that probably like I said the fog of time and reading to many exspurt views from petrol heads who just come out of school or are in school as the case is over here.

Still didnt answer which Spark plug make you prefer? and why?
1991 BX19 TZS 04/01/91 (Deceased)
1990 BX19 TRS 27/10/89 (Reborn)
1992 BX19 TXD (Ex UK - K 744 SDF) 15/06/92
1990 BX19 TZS Auto 06/11/1989
1992 BX TZD Turbo Estate (Ex UK) 1/07/91

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Toddman
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plugs

Post by Toddman » Tue Aug 19, 2008 10:55 pm

You won't go wrong using NGK spark plugs.
I have used several plugs over the years and NGK have always been ultra reliable even in race applications - the 16valve racer also ran the std NGK plugs and that was putting out over 200BHP.
You may find sparkplugs.co.uk isefull for cross referencing.

Cheers
Luke
Please call me Luke :)
1989 BX 16valve White 70k - G764KEW


http://www.bx16valve.com

jeremy
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Post by jeremy » Tue Aug 19, 2008 11:16 pm

I don't have a preference as to make of sparking plug. I'm not saying they're all the same or even don't do what is claimed for them, just the only petrol engine I'm using at the moment is my lawnmower and as that hasn't done the equivalent of 5000 miles - I've never looked at it even though we must have had it for 10 years now.

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jonathan_dyane
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Post by jonathan_dyane » Wed Aug 20, 2008 12:50 am

NGK seconded. They are the dogs danglies IMHO, why bother with anything else...
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