Joined: Feb 2023 Posts: 52 Threads: 15
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Location: Bedfordshire
Car type: Austin Chummy 1930
I have a 1930 Chummy with a 1934 engine, high compression head and L86C Champion plugs.
I don’t do many miles but on the last couple of runs of less than 5 miles one or more have failed. Definitely plug failure as I’ve done the screwdriver to block test to check. Today I replaced 2 and 3. Previously it was number 4.
Timing might be on the over advanced side but when the plugs are good it runs and pulls nicely.
Any thoughts on possible causes or alternative plugs would be welcomed
Joined: Mar 2015 Posts: 5,435 Threads: 231
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Location: Scotchland
Do you have photos of the plugs that you consider have failed.
Joined: Feb 2023 Posts: 52 Threads: 15
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Location: Bedfordshire
Car type: Austin Chummy 1930
Hi Ruairidh , I’m out just now but I’ll post later, they are quite clean.
Joined: Aug 2017 Posts: 678 Threads: 17
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Location: The far North East of England
Car type: 1934 Austin 7 AVH Van (in bits & incomplete!), 1936 Morris 8 Series I Tourer
28-07-2024, 02:57 PM
(This post was last modified: 28-07-2024, 02:59 PM by Jeff Taylor.)
Peter,
I was far from impressed with two new differently numbered Champion spark plugs I bought from a reputable supplier for my two-stroke hedge trimmer and petrol lawnmower. On opening the boxes both had serious manufacturing defects so I complained to the supplier and chose not to use them - there was no country of origin on the boxes, but I suspect China. I then bought a couple of NGK from another reputable supplier and the difference in manufacturing quality straight out of the box was very noticeable. Be aware there's lots of fake NGK and possibly fake other brands on the w.w.web, so buy from a reputable supplier. The NGK plugs I bought have 'Made in Japan' or 'NGK Nagoya Japan' printed on the box.
Champion L86C - these plugs superseded the previous Champion L10 many years ago. The NGK equivalent to L86C is NGK B5HS 4210 but as I mention above, buy from a reputable retailer.
Jeff.
Joined: Mar 2015 Posts: 5,435 Threads: 231
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Location: Scotchland
The plugs in your picture appear to be fouled.
Too rich a mixture or oil coming up the bore? Modern plugs do not have a shiny glaze on the inner ceramic part any more, once fouled you cannot clean it and the plug won’t work.
Joined: Feb 2023 Posts: 52 Threads: 15
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Location: Bedfordshire
Car type: Austin Chummy 1930
Thank you, I rather think it may be oil fouling but I’ll get some new and see how it goes.
Thanks again, an interesting video. BTW, not everyone knows that NGK is from BaNGKok.
Joined: Mar 2015 Posts: 5,435 Threads: 231
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Location: Scotchland
Try running with a hotter plug.
Joined: Feb 2023 Posts: 52 Threads: 15
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Location: Bedfordshire
Car type: Austin Chummy 1930
I’ll try that Ruairidh . Cheaper 1st option than an engine rebuild!