You don't say whether you mean the complete engine or just the head and barrel...If it's the latter get the parts blasted to a bare metal, clean surface and then apply the cylinder paint. I usually apply two coats by brushing as I think this gives better coverage right to the 'root' of the fins...
I did a complete black B33 engine for a customer a few years back...
I had the head and barrel powder coated. This won't stay on the sidevalves as they run too hot so you will have to use cylinder paint...
Then I blasted the rocker covers, timing cover, pushrod tube and crankcases...
I then fitted the main bearings and other fittings to the crank case halves..
Next I masked up all the separate parts over the gasket faces and blanked off any tapped holes...
I then sprayed all the parts with an etch primer suitable for aluminium giving them a good coat of paint..Finally I applied two coats of the satin black requested by the customer....
All paint was applied with a spraygun and the bike has now done about 12,000 miles with the paint finish still intact....
I thought it was good I wouldn't have to polish the timing cover and pushrod tube but actually the paint was much more work and great care had to be taken not to damage any of the paint during assembly, which amazingly, I didn't...Ian
email (option): ian@wright52.plus.com
I run an ally head on my WDM20 and have painted it black just to maintain a more original appearance...
Painting is not required though...The alloy head was introduced in 1950/51 if memory serves and they were fitted in the raw, as cast, finish...
Torque figures for the ally head are the same as for the iron head at 28-30ft./lbs...
Only lubricate the bolt threads with a light machine oil, not grease, before torquing down...
Also use thick washers under the bolt heads to avoid distortion of the bolt seats...I made up .080" washers on the lathe for this purpose..
You'll also need a Champion N5C spark plug or the equivalent, gapped to .018"....Ian
email (option): ian@wright52.plus.com
Painting an alloy head makes no practical difference in my experience...It's still better at shedding heat than the iron heads (which are also painted)..
Barrels and heads were painted 'ex factory' though I don't know what with...
Rear view mirrors were not fitted as standard to any BSAs as far as I am aware...Ian
email (option): ian@wright52.plus.com
Photographic evidence suggests that mirrors were almost never fitted to motorcycles in British service and no self-respecting British R.S.M. would have allowed it...
"What's that bloody ladies' powder-puff mirror doing on a service motor-cycle, you 'orrible little man...?"
That said, the Canadians (once again a law unto themselves)do seem to have fitted them during the latter stages of the war in Europe. They'd have purloined them from somewhere...presumably other vehicles.
Ron will know better, but is the rectangular sort sometimes seen as fitted to CMP pattern trucks or Carriers ?
However, they're the exception rather than the rule and might be OK on Lines of Communication / Rear Echelon provost duties but were unlikely to have been a common sight up at the sharp end.
email (option): 79x100(at)gmail.com
It wouldn't have been a great idea on active service to have a highly reflective surface on your bike on a sunny day I wouldn't have thought...
For the sake of appearances I share Rons reluctance to fit a mirror to any of my old bikes...I just look behind as required...Ian
email (option): ian@wright52.plus.com