Should we use anti seize on spark plugs?

by Ed R in General Tech Discussion 7 years ago

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Re: Should we use anti seize on spark plugs?

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

Here you go. This will last you forever. Get the smallest tube.

https://www.amazon.com/gp/product/B005DNQWQU/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: Should we use anti seize on spark plugs?

by Ed R » 7 years ago

Ed R

5 16 14

I can't view the video because I'm not a subscriber but I did the spark plug change two days ago, using that exact same stuff applied with a fingertop in a couple of spots near the top of the threaded portion. Engine runs well, in fact it's been starting much more easily than before - I suspect because I gapped them to 0.025" and they were almost certainly at 0.028" before.

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Re: Should we use anti seize on spark plugs?

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

When you get too wide a gap the spark has a harder time crossing the gap and it can be weaker. This is why plugs have gap specs.

From the Green Spark plug:

The belief that plugs are properly gapped as delivered in their box from the factory is only partially true, as proven by the fact that the same plug may be specified for several different engines, requiring a different gap for each.

The main issues with spark plug gaps are:
1. narrow-gap risk: spark might be too weak/small to ignite fuel;
2. narrow-gap benefit: plug always fires on each cycle;
3. wide-gap risk: plug might not fire, or miss at high speeds;
4. wide-gap benefit: spark is strong for a clean burn.

A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle. Spark plug eroded: note the center electrode (dark bump) had been a cylindrical rod, and the top ground electrode (like a claw) formerly had square edges.

As a plug ages, and the metal of both the tip and hook erode, the gap will tend to widen; therefore experienced mechanics often set the gap on new plugs at the engine manufacturer's minimum recommended gap, rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realise that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace or re-gap the plugs much more frequently, as soon as the tip begins to erode.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: Andrew Dunning

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Should we use anti seize on spark plugs?

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