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#1
15-04-20, 02:34
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Just from a practical standpoint, how do you adjust the gap on a four electrode plug if you don't have the special tooling. I suspect that this cannot be done in the field therefore necessitating plug replacement.
Single electrode would have to be a better proposition for earthbound application and work just fine on millions of engines. David
__________________
Hell no! I'm not that old! Last edited by motto (RIP); 15-04-20 at 02:40. 
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#2
16-04-20, 04:09
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R975 sparkplugs
Thanks Malcolm and David for your thoughts.
I think maybe you have it- aircraft plugs are too difficult to service in the field? seems to make sense. Much of what I have read suggests radials have a bad habit of fouling plugs and need frequent changes of plugs. So this could be due to a too rich mixture at low speeds or too much oil working its way up to the plugs? I have pulled apart engines where the top rings are all seized- probably due to oil leakage toward the combustion chamber. Too much oil will certainly foul the plugs, an ongoing problem in radial type engines.
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#3
17-04-20, 21:06
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Just a footnote to this discussions on sparkplugs. I was out rooting through one of my trailer, looking in boxes I put away 25 years ago and I found some more, radial/aviation style engine sparkplugs. The first another Champion C63, but with a twist. check out the twin electrodes. It the first one I remember seeing.
Second I found a couple of cartons of plugs for the Light Tank (Locust with Lycoming air cooled aviation engine) which are also Champion plugs. Note they are single electrode and unshielded. Here are a few pictures. plugsa.jpg plugc.jpg plugd.jpg
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#4
17-04-20, 21:26
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If anyone finds spark plugs with electrodes like the above, single or double, the thin piece welded to the threaded portion is platinum. Do not try to change the gap as they will fall off. However if the plugs are scrap it makes it easy to separate the platinum which is well worth doing - check the price !
David
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#5
18-04-20, 13:45
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Quote:
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Charles Fitton Maryhill On., Canada too many carriers too many rovers not enough time. (and now a BSA...) (and now a Triumph TRW...)
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#6
19-04-20, 05:18
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You have a helluva stash of parts, Bob!
The Brits liked those "fine wire" plugs shown in your third photo. Ive seen them on Ferrets and an FV432. Like David said, the pins are platinum or ididium and they are a high-end plug for aviation use. Good for burning off lead deposits, which I found out aviation gas still has, much to my surprise. Nowadays they cost over $100 each, so $1000 for a four-banger aircraft engine! Total overkill for a museum vehicle. Malcolm
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#7
19-04-20, 15:45
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Most AvGas sold in Canada at present is 100LL. I.E. 100 octane Low Lead (max 0.56g/l of lead).
See https://www.shell.com/business-custo...uel/avgas.html for more information about AvGas.
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