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 WHAT HAPPENS
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schakal
Spammer

Joined: 27 Jul 2004
Posts: 5717

Posted: Fri Dec 03, 2004 3:06 pm

what happens if some muppet adjusts the spark plug gaps wider than they are supposed to be ?? and i am on about well wide like 1.5mm instead of 0.8 mm
how would it effect running ,fuel consumption ???
Chris H
Forum Moderator

Joined: 02 Mar 2004
Posts: 19978

Posted: Fri Dec 03, 2004 3:07 pm

more missfires, worse mpg, poor pickup

at idle etc it would be fine, or even just revving the car stationary, under load though things are different.
schakal
Spammer

Joined: 27 Jul 2004
Posts: 5717

Posted: Fri Dec 03, 2004 3:17 pm

would it damage the engine in the long run ? or would getting new plugs sort the problem ?
schakal
Spammer

Joined: 27 Jul 2004
Posts: 5717

Posted: Fri Dec 03, 2004 3:17 pm

i am a muppet by the way
Chris H
Forum Moderator

Joined: 02 Mar 2004
Posts: 19978

Posted: Fri Dec 03, 2004 3:28 pm

just get new plugs, won't even cost a tenner.
Roger Red Hat
Site Subscriber

Joined: 13 Oct 2004
Posts: 4722

Posted: Fri Dec 03, 2004 3:29 pm

new plugs = sorted..

all its doing is making a weaker spark..

bigger gap for the spark to jump.
Roger Red Hat
Site Subscriber

Joined: 13 Oct 2004
Posts: 4722

Posted: Fri Dec 03, 2004 3:30 pm

damn you chris, i was in the mids of posting that!
Chris H
Forum Moderator

Joined: 02 Mar 2004
Posts: 19978

Posted: Fri Dec 03, 2004 3:32 pm

its not making a weaker spark as such its more a lack of spark

why woudl a spark jump the gap in the combustion chamber which has high resistance when it can track through the HT leads or cross fire in the cap.
schakal
Spammer

Joined: 27 Jul 2004
Posts: 5717

Posted: Fri Dec 03, 2004 3:36 pm

ferk me !!
thats the first thing they teach you about electrics
electric current always choses the shortest way .
cheers
Roger Red Hat
Site Subscriber

Joined: 13 Oct 2004
Posts: 4722

Posted: Fri Dec 03, 2004 3:37 pm

ah rite. cos its got to take longer to build up to jump the gap yes?

more voltage?

there for a lack of spark when its needed?

my leccys sucks Sad
Alex C
Level 6 User

Joined: 20 Jun 2004
Posts: 155

Posted: Fri Dec 03, 2004 3:50 pm

Its not so much the time thing, its the fact that electricity really doesn't like moving through air much (or air and fuel for that matter). Therefore, if you have a big plug gap, you will need a larger potential difference on either side of the gap (or voltage across the gap if you like) to pursuade the electricity to flow across the gap. Since the iggy system in a car usually only generates a relatively fixed voltage to the plugs, if you have an overly large plug gap, the electricity will find an easier way around (which means arcing in the cap etc.).

Bottom line - electricity is lazy like me Very Happy If it has a choice of two paths, it will always always choose to flow through the 'easier' one, which in electricity terms means the path of least resistance. Air = very high resistance, so pretty much anything else is preferred by electricity. Or in absence of that, the smallest amount of air it has to travel across is the one it will go for (hence the arcing in the cap).

Hope this makes sense and I haven't forgotten GCSE physics too much Smile

Cheers
Alex
Chris H
Forum Moderator

Joined: 02 Mar 2004
Posts: 19978

Posted: Sat Dec 04, 2004 9:04 am

aye thats right.

Main factor is though the resistance in the chamber varies so missfires may only happen at certain loads/times.
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