Egt probe help?!

[beefalobilly]

I got an EGT probe from aircraft spruce, it says it's a 1/8 NPT. Does 1/8 NPT only have 1/8 interior diameter???

It came with a fitting with two male threaded ends. One end is about 1/4inch, this is where the probe goes on, the other end goes to the exhaust manifold and is a little less than 3/8inch.

I went to OSH and I couldn't find anything that fit it (i looked for nuts so I knew what the thread size/type was)

I'm really confused now as to what tap to use on my exhaust manifold. The only thing on the fitting that is 1/8 is the interior of the exhaust manifold side (the threads are about 3/8)

[beefalobilly]

ttt someone help please!

[abstract_72]

I installed a an aircraft spruce EGT probe.
NPT means national pipe thread, it really won't measure 1/8.
Go to the hardware and get a 1/8 NPT tap and the appropriate drill bit.
(Practice a couple of times)
The NPT basically means it is a tapered thread so it gets tighter as it goes in, so you want to tap it the appropriate depth...thats why trying it on some scrap first is helpful. Hope that helps.

[cybermrc]

Also be careful when you are tightening it up as to NOT overtighten it and break it!
Only tighten it about as much as you would, say, a spark plug.

I'm not sure if i understand you correctly but let me take a stab at this. You have an adapter fitting with 1/4" dia threads on one end and 3/8" on the other. The 1/8" npt means the i.d. of the pipe is 1/8". There fore the threads would have to be larger. The other side is probably 1/4" pipe. I assume that both sides of the adapter are male threads. The egt probably attaches to the 1/8" pipe side of the adapter. So the other side is threaded into the manifold. If i'm correct you will need a 1/4" pipe tap to tap the manifold. For some reason i can't remember right now which drill size that is. However, FYI, the 1/8" npt tap uses an 11/32" drill bit.