Case mount or boss mount? Which is which

[MattPearson]

I know this may sound like a dumb question, but can someone post some pictures or just describe the difference between the two when it comes to mounting and alternator?

Thanks

[Jekyll]

Go to this web page:

http://www.plane-power.com/Mount_Systems.htm

If you are running a lycoming or lyclone you'll be needing one like this in the boss mount:

http://www.plane-power.com/AL12-EI60.htm

This is new model that Van's sells for $375. It has internal regulation and a crow bar. Bob Nuckols of the Aero Electric Connection recently came out and said this as the only internally regulated alternator he recommends.

It's only a dumb question if you don't ask it before buying the wrong mounting style.

Jekyll

[Mel]

The boss mount has a "boss" cast onto the crankcase. The case mount has a bracket that mounts to the spine bolts.

[gmcjetpilot]

I'll Add..........

Most lycomings made in the last 3 decades have boss mount. The older engines are the ones with case mount. Boss mount is much better. The case mount brackets work but are subject to more bending and likely to crack easier.

[MattPearson]

Awesome! Thanks gentlemen