CHT top or bottom plug?

As the title says, do the CHT spark plug style thermocouples go on the top or bottom plug, or does it matter? If this is a dumb question please take it easy on me.

top

Put 'em on the top plugs.

Top?

With the engine mounted they are on the bottom
Top plugs are for primer.

I haven't used the spark-plug-ring type sensors since my Grumman days, but I recall trying them on both top and bottom over the years - no difference in sensing, and each had their pros and cons for ease of servicing. Unfortunately, either way you go, they are a pain compared to bayonet sensors that you don't have to fool with every time you remove and replace spark plugs.

Paul

agirard7a said:

With the engine mounted they are on the bottom
Top plugs are for primer.

Click to expand...

I could be mistaken here, but I think this post is referring to the bayonnet style CHT probe.

In the spark plug ring type installations I've seen they have always been on the top spark plug.

Tops

Top it is. Thanks for input.