Do spark plugs age..?
04-27-2005, 08:45 PM
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Do spark plugs age..?
hey all..
I am getting ready to smog my car...so looked up when my car had plugs done...
done @ 60k and have only 76k now...but the plugs were changed in 1997 ...car wasn't driven for a while when I bought her...I pulled one and it looked good..but I'm not very experienced so what good is that ?
i guess for $20 it wouldn't hurt to change...but I hate throwing money away if the plugs are good...
Although it is time for new ignition wires...mine are original...was thinking to get Paragon's set for 944S...haven't called them yet, as i don't see them listed on their web page...
any thoughts...
TIA
dan
I am getting ready to smog my car...so looked up when my car had plugs done...
done @ 60k and have only 76k now...but the plugs were changed in 1997 ...car wasn't driven for a while when I bought her...I pulled one and it looked good..but I'm not very experienced so what good is that ?
i guess for $20 it wouldn't hurt to change...but I hate throwing money away if the plugs are good...
Although it is time for new ignition wires...mine are original...was thinking to get Paragon's set for 944S...haven't called them yet, as i don't see them listed on their web page...
any thoughts...
TIA
dan
04-27-2005, 09:19 PM
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As long as they are not all rounded off regap them.
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83 944 = It's NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts
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04-27-2005, 09:38 PM
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Spark plug gap should be on the emmissions placard in the engine bay. Fender well I think.
__________________
83 944 = It's NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts
and/or cam chain and tensioner?
The 83
__________________
83 944 = It's NOT a 'real' Porsche -- Its Better!!!!
When was the last time you changed your timing and balance belts
and/or cam chain and tensioner?
The 83
04-27-2005, 10:28 PM
#6
Three Wheelin'
OK, here's the LONG answer..
Plugs don't "age", but they do wear out.
Each time the plug is fired, a small electrical arc forms between the two electrodes.
Each time an arc is formed, a small amount of metal gets transferred from one electrode to the other, and a small amount of metal is lost.
As the miles pile up, the metal loss shows up as an increase in the spark gap, and the electrodes have rounded edges. Funny thing about electrons is, they like to "jump" to and from sharp edges and sharp points.
When the electrodes get rounded it takes more energy to get the plug to fire because the electrons are spread out over a wide area as opposed to being crammed into one sharp edge or point. Add to that the increased spark gap, which requires still more energy to get the spark to jump, and you come up with a "weak" spark.
From there we get into all sorts of combustion and flame front/propagation theory, but I think you get the idea.
You can clean and re-gap these plugs if you want to, but you need an ignition or other small file to square up the electrodes and a plug gap tool to set the gap.
If I were you, I'd just buy a new set of plugs and an inexpensive gap gage, check the new plugs, throw 'em in, and keep the old ones for spares.
Plugs don't "age", but they do wear out.
Each time the plug is fired, a small electrical arc forms between the two electrodes.
Each time an arc is formed, a small amount of metal gets transferred from one electrode to the other, and a small amount of metal is lost.
As the miles pile up, the metal loss shows up as an increase in the spark gap, and the electrodes have rounded edges. Funny thing about electrons is, they like to "jump" to and from sharp edges and sharp points.
When the electrodes get rounded it takes more energy to get the plug to fire because the electrons are spread out over a wide area as opposed to being crammed into one sharp edge or point. Add to that the increased spark gap, which requires still more energy to get the spark to jump, and you come up with a "weak" spark.
From there we get into all sorts of combustion and flame front/propagation theory, but I think you get the idea.
You can clean and re-gap these plugs if you want to, but you need an ignition or other small file to square up the electrodes and a plug gap tool to set the gap.
If I were you, I'd just buy a new set of plugs and an inexpensive gap gage, check the new plugs, throw 'em in, and keep the old ones for spares.
04-27-2005, 10:52 PM
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If you're going to try to pass smog, i'd also suggest checking the cap and rotor for wear. Changing the cap, rotor, and spark plugs made a HUGE difference for my smog results and helped me pass.
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04-28-2005, 12:55 AM
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Big thanks for the gap theory...I had a friend in college who made a tesla coil and I remember the sharp edge stuff now...
I'll look at the plugs again with this new understanding...
I did have the rotor and dist. cap changed recently...
peace
I'll look at the plugs again with this new understanding...
I did have the rotor and dist. cap changed recently...
peace
