Sparking plugs

[bob hughes]

Finally sorted my sparking plug problem out but not before I had a terrible trial on the Goodwood racing track last week end, when one after an other the new Bosch plugs whent down and I ran out of my old spares, 'cause I only took 4 with me. I had been sold the wrong plugs, these were cold plugs and my car absolutly needs hot plugs as it burns oil. I had heard about hot and cold plugs but never knew the reasons and which was which, now I do.

Still that's experience for you, you are never too old to learn.

Bob

 

[RobWarren]

Bob I'd never heard of hot or cold plugs until just now.

Keep passing on the knowledge, brother.

Bob

 

[Roger]

A word of warning about hot (soft) plugs and cold (hard) plugs.

Hard plugs run cooler because they have more heat-ransference material in their construction. Soft plugs burn hotter, which has the side-benefit of dealing with (by burning) oil deposits. But they will also burn out themselves under stress, and can take piston tops and other components with them.

So if you use soft plugs under high-performance conditions, be careful. Use the hardest plug that won't oil up, not the softest that won't burn up, for safety.

 

[bob hughes]

Roger
You are quite right there is a danger of burning things out. It would be interesting to see what the style of the Champion plug is that is specified in the workshop manual, As my car came with NGK plugs I have no idea.
The hot plugs that I am using have a deep recess around the central isolator and therefore there is a small isolator/metal contact down at the bottom - not so good for heat transfer, the cold plugs that I had bought have a shallow depth around the central isolator hence greater isolator / metal contact- more heat transference.
Any one know what the champion plugs are like?

Bob

 

[zblu]

Original plugs for the 100 was NA8 25 thou gap and NA10 for Le Mans
And below for some good info
https://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html