[TR] Sparkplugs for TR3A

[Randall]

IMO soot on the plugs always means you are running too rich, at least part of the time. Since idle mixture is fully adjustable, I would first check it by the book (lift the piston test), then if that still puts soot on the plugs, try going leaner a half flat at a time.

Note that it's also easy to get soot on the plugs when starting from cold, which may take some time to burn off, even running under load. Also, you should be looking at the insulator near the gap, as the metal shell may never get hot enough to burn the soot off.

Problems with float level (leaky float) or a leaky float valve can also cause sooty plugs.

My point of view, hotter plugs are only a workaround for things like excess oil consumption.
-- Randall

On 27 May 2019 13:17:09 GMT-07:00, Dave MacKay <dave at mdmackay.ca> wrote:
> Sparkplugs for TR3A
>
>Hello:
>
>I’ve been running Champion L87Yc plugs in my 1960 TR3A, gapped to
>0.025”. Although
>they’ve been fine, I’ve always been concerned about the amount of soot
>on
>them at the end of each driving season. Thinking the soot might be dur
>to
>too rich a mixture, I rebuilt my carbs but didn’t notice any change in
>the
>amount of soot. It was suggested that I might want to try a hotter plug
>since that might burn away more of the soot. According to Champion, the
>next hotter plug to the L87YC would be the L92YC.
>
>What concerns ought I be aware of in running a hotter plug?  Has anyone
>of
>the list had experience with L92YC plugs?
>
>I researched other plugs that list members are using and found that
>several
>have had good success with NGK BP6HS. According to NGK those plugs have
>been discontinued and the recommended replacement is the BPR6HS (same
>plug
>but with a resisitor). I thought I might try a set before moving to a
>hotter plug.
>
>I’d welcome any comments.
>
>Dave MacKay
>
>1960 TR3A s/n 68639L
>
>Near Toronto, Canada
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