Topic: Shorty 18 mm spark plugs? – Antique Outboard Motor Club,Inc

This topic has 10 replies, 6 voices, and was last updated 5 years, 4 months ago by Buccaneer.

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October 19, 2019 at 10:48 pm #185618
Buccaneer
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US Member
In researching what spark plugs I should use for the 1937 Evinrude Imperial
Lightfour “high pressure” pump motor, I find Champion M5, which
I believe matches up to Champion D9 (509).
I was just wondering if there’s any 18 mm “Shorty” plugs out there?
The front engine cover comes awlful close to the current old plugs.
Thanks.

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October 20, 2019 at 11:04 am #185631
garry-in-michigan
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Lifetime Member
I see you have the wrong nut on the lower spark plug on the port side. Use the short knurled nuts and you won’t have any problems.
October 20, 2019 at 12:11 pm #185634
Buccaneer
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US Member
Garry, I’ve ordered some Champion D9’s, and will check them for length
when the come, and use the knurled nuts, if the thread fits.
Thanks.

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October 20, 2019 at 12:40 pm #185637
wbeaton
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Canada Member
Newer plugs are longer than the originals. Best to use knurled nuts on old plugs. On my PO-15 I used modern plugs and then wrapped the tops with electrical tape. Rubber boots were an option, but I didn’t want to change the original rajah terminals since the wires were in nice condition.

Wayne
Upper Canada Chapter

uccaomci.com
October 20, 2019 at 3:30 pm #185639
Buccaneer
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US Member
One would have thunk they’d make shorty 18 mm plugs for something important,
like old airplanes or obsolete equipment the Government still has in inventory.
Guess I’ll just “plug” away and see what happens!

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October 21, 2019 at 12:02 pm #185674
IAN
Participant
the AC 82M plug has a short insulator on it. They used them in the 1929 Elto Lightweight. Short insulator plu will fit inside the spark plug cover on the Elto.
October 21, 2019 at 3:39 pm #185680
Buccaneer
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US Member
IAN wrote:

the AC 82M plug has a short insulator on it. They used them in the 1929 Elto Lightweight. Short insulator plu will fit inside the spark plug cover on the Elto.

Good to know. Thanks Ian!

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October 21, 2019 at 4:20 pm #185686
Buccaneer
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IAN wrote:

the AC 82M plug has a short insulator on it. They used them in the 1929 Elto Lightweight. Short insulator plu will fit inside the spark plug cover on the Elto.

I’m not seeing these plugs listed for sale anywhere.

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October 21, 2019 at 5:22 pm #185692
Tubs
Participant
.

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.
- This reply was modified 4 years ago by Tubs.
October 21, 2019 at 5:32 pm #185694
labrador-guy
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US Member
Buc, what do you think about coating the inside of the front cover where the plug wire come close with some liquid tape? I have one of those four banger fire traps and I am thinking like you. I would like to insulate those wires better. I never used any of that liquid tape but I think I am gonna look for some.

dale
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