graememk
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| posted on 7/5/07 at 10:07 PM |
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silly spark plug question
i have a fueling problem on my engine and cant at the momnet run high rpm, but on the way back from stoneliegh i though my car wasnt running great and
lacked much power.
anyway i had fitted colder plugs as a recomendation but when i put them in i never thought about checking the gaps
i did it today and it now runs much better, it was set to .35m now 1.1mm
could someone please tell me why a engine runs better with a wider or closer gap, i'd of thought the closer the stronger the spark
[Edited on 7/5/07 by graememk]
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Howlor
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| posted on 7/5/07 at 10:22 PM |
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I could be really wrong here but!
I thought that a smaller gap meant that a weaker spark can jump, where as increasing the gap means that a certain strength of spark is required to
leap the gap and therefore a better spark?
May be totally wrong but worth a pop.
Steve
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oadamo
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| posted on 7/5/07 at 10:31 PM |
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i run a small gap on my turbo engine as the tuner said the boost would blow the spark out dont no if its true but i run 1 bar boost and its ok
adam
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Bob C
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| posted on 7/5/07 at 10:46 PM |
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Wider gap = bigger spark (good) but also = higher voltage hence more stress & likelihood of HT problems. Recommended spark gaps are as wide as
possible without breaking down all the HT components.
Compressed gas has its atoms closer together so ions don't pick up so much speed between collisions - therefore compressed gas needs more volts
to sustain an arc. Therefore turbo engines have a smaller spark gap.
Also explains why HT problems often become apparent on full throttle (max cylinder pressure) not idling (low cylinder pressure)
Bob
PS waveguides used for high power microwave transmission are often pressurised to prevent internal arcing
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Peteff
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| posted on 7/5/07 at 10:51 PM |
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It's to do with spark duration as well. A small gap means a short spark causing poor starting and combustion. Too much gap may be too much for
the ignition system and cause misfires.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Fatgadget
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| posted on 8/5/07 at 12:18 AM |
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It's a compromise as per above post. Why don't you give MSD a shot?
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Humbug
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| posted on 8/5/07 at 06:48 AM |
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quote:
Originally posted by graememk
i have a fueling problem on my engine and cant at the momnet run high rpm, but on the way back from stoneliegh i though my car wasnt running great and
lacked much power.
anyway i had fitted colder plugs as a recomendation but when i put them in i never thought about checking the gaps
i did it today and it now runs much better, it was set to .35m now 1.1mm
could someone please tell me why a engine runs better with a wider or closer gap, i'd of thought the closer the stronger the spark
[Edited on 7/5/07 by graememk]
Not surprised it wasn't running very well with a gap of over a foot 
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