SonexBuilders.net

Hello Everyone,

Merry Christmas to everyone! I hope everyone is having an excellent holiday season and enjoying some time at home with family and loved ones.

This has probably been asked before, but I’m curious for those of you who have a non-4th generation Jabiru 3300 and MGL avionics: how and where do you secure MGL CHT probes to the heads of the Jabiru? I know the new 4th gen Jabiru’s have a designated brass screw by the spark plug holes, but for an older engine, where do you install them? And, what CHT probes do you use?

On the AeroVee heads we drill a small hole in the head for a self tapping screw and the probe sits on the head, but I wasn’t sure how the Jabirus work. If I need to order new CHT probes I’m hoping to get a jump start on that sort of thing!

I appreciate your help and hope everyone has a Happy New Year!

Mike
(Still waiting on my Jabiru to be rebuilt)

Try this:
https://jabiru.net.au/wp-content/upload ... or_mod.pdf

I originally bought the spark plug washer type CHT probes but of course made the discovery that there was no way they were going to fit. Instead I fitted them under the nearest head bolt using some aluminium "top hat" washers to center the 12mm probe on the 5/16" bolt and ensure good thermal contact. I also used slightly longer head bolts to allow for the extra thickness. Probably easier than the method recommended by Jabiru, but only if you have access to a lathe.

Peter

I've put mine under the headbolt over the exhaust port. You may need to slightly bend the fin to slide it in.

Iv'e tried all three methods. In my opinion the latest Jabiru recommended method is the tidiest.

50 hrs under the head bolt. When tensioning the heads the the copper ring lug would drag, rotate and distort under the head bolt.

The next 150 hrs under the spark plug. Was always a hassle when re installing the plugs.

The last 200 hrs in the tapped tooling hole between the plugs. Can remove plugs and re tension heads without interfering with the CHT lug.

Thanks guys! I was secretly hoping there was a good spot somewhere in the head where a small hole could be drilled for the sensor and a self tapping screw, which would be in the exact same manner as the AeroVee heads. According to Bill’s link, there is sufficient area right there by the plugs for that to work.

As an added bonus, I am hoping I can simply reuse the same probes I already have which would be great!

Thanks again!