I was recently given this engine as half of a leafblower - I understand that it's a McCulloch, at least that's what was written on the instruction book that came with it.

A couple of afternoons work and it looked like an airplane engine... I've done the following work:

Complete stripdown and clean
Cut off excess bits of casting from the crank-case
Made engine mount
Turned a prop-driver, prop washer, cut off and threaded the main shaft
Turned the fins off the front of the magneto flywheel
Exposed the (protected) needles on the carb for tuning
Screened the ignition lead
Opened up the muffler a bit by drilling out the outlet hole through both muffler chambers.

The engine runs fine, both on the ground and in the air. Starts by hand very easily. I've measured 6800 revs on a Menz 18x6 prop - that's what I'm flying it on.

But...

Is there anything else I can do to improve the engine? To my mind you can never have too much power or too light an engine...

I've considered packing the crank-case and crank-web. Is it worth it?

What about port timing? Any gains here? I'm certainly not new to petrol engines, but know very little about removing metal from the insides of them...

What else would you do to the engine?