R43T plugs?

[Keller]

Happened upon an interesting situation the other day.

Was helping a local clubmember straighten out some kinks in a "new" TR. Another local clubmember has devoted a lot more time to aiding in the project. As a result, they picked up a set of plugs and installed them in the car.

Obviously, we have beaten the topic of plugs on these cars to death, and have pretty much arrived at some common standards. But their choice threw me for a loop: R43T. Is that really an appropriate part? They insisted it was. Hmm...

Heat-range-wise, its a good choice. However, the center electrode and the insulator are a bit further up in the plug body. Dare I say almost shrouded by the plug body. I have never heard of these being used in this application, and was a bit baffled by it. IThe V6 NA cars with HEI used a R45TSX. The X meaning "extended reach", and thus going deeper into the compression chamber.

Is the plug they used really applicable? Maybe for ultra-high boost? Why would you want a plug that like the R43T? Or is it simply the wrong tool for the job?

[kenmosher]

Well, the "S" in the typical plug we use (CR43TS for example) is extended tip. Which is a good thing in our combustion chamber shape.

The tip being more shrouded in the 43T could make the spark effectively "weaker" under high boost since it is more shrouded.

C = Commercial (heavier duty electrode) / M = Marine
R = Resistor
4 = thread size (14mm)
3 = heat range
T = tapered seat (no gasket needed)
S = Extended tip

My opinion is that they are using wrong plug without the extended tip. The non extended tip plugs are sometimes used with engines with domed pistons or more side oriented plug arrangement.

[Keller]

That was my opinion, too. They cited a noted member of the TR community, but I really don't want to get into a battle of wits over it.

I'd better tell the owner...