SonexBuilders.net

Had a spark plug blow out of the head of my new-to-me Sonex with the Great Plains 2180 engine due to previous helicoil repair (made the return to runway from 200' interesting).

Not having much luck finding a replacement head from factory. Plane is stranded in Alabama on way back to Venice FL.

Does anyone here have a spare head for this engine that they would like to sell? The valves are 40 mm and 35.5 mm and I need the head that is drilled for redundancy. If not, does anyone know of another manufacturer that makes a compatible head like the Great Plains head?

Thanks

Id think you would get a better response at https://www.homebuiltairplanes.com/

My experience with great plains has been that they are not responsive to emails but anything Ive ordered online shows up a week or so later.

Other options would be Cassler and Aerovee but Im not sure they sell aerovee parts for use on other engines. The combustion chamber size is important to know as well.

For a ferry flight home, welding the plug hole shut may be an option? Just throwing ideas out there.

Give Scott Casler at Hummel engines a call.
You can buy his heads, machined for dual ignition, or purchase a head from your favourite brand, send it to him and have that machined.
My recommendation would be to purchase a set of 2 directly from him so you have the same on both sides. Depending on which GP engine you have you’ll need either a 92mm or 94mm bore head. You’ll also need a new set of pushrods and calculate your desired compression ratio based on the new heads chamber volume so you know what thickness of copper gaskets to use (if any)

Many of us have had plugs blow out or had stripped heads with VW's. Mine was with the Aerovee. The answer is to use a Time-Sert. It is similar in theory to a Helicoil but much better for the application you need. Don't use a Helicoil for this use a Time-Sert.

I had 2 of them on my Aerovee and they are better than the original head. There is a discussion somewhere on this forum regarding just this issue. I did not even have to remove the head to make the repair. The key was to use heavy grease on the tap to grab any shavings from screwing the tap into the head. Then use compressed air and a borescope to verify that there aren't any chunks in the cylinder. Next, simply screw the Time-Sert of the correct size for the spark plug with the insert tool, and you are done!

This is an easy repair and the result will be a better stronger plug thread environment.

Here is a link to one of many Youtube videos showing how to do this repair.
https://www.youtube.com/watch?v=e0NXlxfUmoI