spark plug advice

[TCTrev]

whats the best spark plug for my 1949 tc

[Steve Simmons]

You'll likely get a few different answers, but I've been using Champion L86c for tens of thousands of miles with good results. Just make sure you get 1/2" reach plugs if you have the original head installed. Late TD/TF heads use 3/4" reach.

[tone]

As a matter of curiosity, and slight concern, as I'm rebuilding engine now, and probably a silly question
but how do you know what length plugs are the correct ones, other than sticking a tape down the hole!

[Steve Simmons]

Someone correct me if my memory is failing, but I believe a casting number of 22952 is an original TC head and will use 1/2" reach plugs. The later TD/TF head with casting number 168422 used 3/4" reach plugs.

[Duncan M]

I agree with Steve on the Champion L86C spark plugs for a TC head. Standard tip, non resistor.

Some will tell you to only run projected tip spark plugs, but I have found the equivalent heat range (L92YC) in projected tip to cause poor running at times.

Original plugs from the factory were L10S which are standard tip.

Of course if you were building a high RPM racing engine then you would use much cooler plugs.

[Franz Tenbrock]

Hi
and what plugs for a Laystall head ?
the same?

[Steve Simmons]

I think I would try the same range of plug, and if they tend to foul or get gunked up then I'd go one range hotter. I don't recall if all Laystall use the same reach plug or if they made both 1/2" and 3/4".