Hi Keith,

> but I still can't fillet the portion behind where the cylinder head is to
> be fitted (top middle).

I'm not quite sure of the area you're referring to, is it this one here:




That's certainly going to be difficult to fillet - not only is there not much space in the flat part, but since the rounded part on top is flush with the side wall below it, it causes a kind of "vanishing fillet" type situation where the fillet would kind of narrow down to a single point, those are not handled very well by the filleter right now.

It will probably require some pretty low-level and pretty involved individual surface manipulation to finish up that part, the more "automatic" edge filleter is not able to handle that area. I can try to help you with that some more tomorrow if you want, but I want to make sure of the area you want to have filleted first.

- Michael