[Geeman]

About to go to hanger and start working to install EGT probes. Anyone know the hole size to drill the exhaust before I start searching for it?

 

[BobTurner]

Do not have the size here, it may depend on whose probes you are using. But you will need some good carbide bits, several of them, as they will be dull by the time you are done.

 

[Clint B]

Egt hole size

There are several different egt probe sizes, the most common are in the 1/8" range. I would suggest getting a good new bit to drill the holes and use cutting fluid on each hole. Be sure to use the slow speed setting on your drill, otherwise you are likely to work harden the metal. Last but not least, BE SURE that your egt probe will be in a location that won't interfere with the cowling, we have welded literally hundreds of holes shut that were in the wrong place!

 

[Geeman]

Thanks for the good info. I love this forum.

 

[gasman]

Standard drill bits will work just fine if new. Do a generous center punch. Drill in two steps, first 1/2 size, then final.

Start the bit turning SLOW with no pressure..... then apply a good amount of pressure. Keep it cutting and don't back off. As long as it's cutting, it won't over heat and harden. This is thin wall, it will be over in seconds.

 

[N526JS]

About to go to hanger and start working to install EGT probes. Anyone know the hole size to drill the exhaust before I start searching for it?

Hmmm.. Do you have the probes at hand? If you do then it is easy enough to mic them or just hold some drill bits alongside to determine a proper diameter, that's what I did. You can be a bit conservative on the size of the hole and if the probe does not fit just use the next larger bit to expand it.

Don't even think of drilling a hole without the probes on hand as you will definitely need to check clearances before you start. Otherwise, you will likely be giving a welder some business.