Companion W&B, engine choice

I'm curious about the Companion's W&B, and ultimately my engine choice. I've read that an "angle valve" engine, e.g. the IO-360 variant or IO-390, is necessary due to their weight and the Companion's engine mount (arm). I found this W&B diagram on the Bearhawk website. The diagram doesn't include an engine arm. Assumptions, if any, aren't provided. And it lacks details such as weights. I'm hoping that someone can provide a completed Companion W&B diagram and details about the their final options. From there I could estimate W&B, e.g. using the currently available kit components and engine options, and calculate the C.G. with various fuel and cargo loads.

You are thinking ahead by doing the CG calculations. An engine's CG is documented in the engine's type certificate data sheet. This is an FAA document that is available on line. For Example, The TCDS says a Lycoming IO-360-a1a engine is 293 lbs. with a CG of 14.24" aft of the prop flange. A drawing of the enigne will show how this relates to the engine mount.

I cannot confirm this, but I have heard that an O-320 with a fixed-pitch prop allows no more than 50 pounds of baggage before the CG is too far aft. I can't remember who told me this, but it falls into the category of information provided by an expert. I know Virgil has told me I can't get it too far forward with an angle valve 360 and a constant speed prop to where I would have to carry ballast. That's my biggest concern as I likely won't be packing heavy loads except to and from the occasional camping trip.

My Companion, with an angle valve 360 and a fairly light ground adjustable prop, has an empty weight CG of 14.6. Pretty much the middle of the 11.9 to 19.8 limits. Since the people/fuel/baggage Arms are all positive, it's the aft limit that matters and a heavier engine/prop combination is better. I have no trouble believing an O-320 would be impractical.

Recommended engine for optimal CG is an Angle valve IO360 or IO390 with a contestant speed prop. Lighter parralelle valve engines will severely limit your cargo capacity.