Springs & Sandpaper.

Here are some photos of the cylinder head. When Peppe was assembling the valves he noticed something very interesting: it would appear that the BSA A50 was fitted with progressive valve springs at the factory (by contrast, the 650s weren't). Even more interesting, the ends of the springs are shaped so that they can only be installed in the correct direction (closed coils towards the head) - in other words the spring collars only fit one side. Fool-proof. (that said, make it idiot-proof and someone will make a better idiot).

The exhaust rockers are installed only once the head is bolted on to the rest of the engine, otherwise the rocker spindle would be in the way of the two bolts/studs.

In other news, I've spent a little bit of time on the smooth valve cover. Here's what it looked like when I bought it. And here's how it's looking now:

I used dry and wet sandpaper, some abrasive paste and about one fluid ounce of elbow grease. It's by no means flawless but I think I'll leave it pretty much like this. I like the dull shine it has, I think if it were as shiny as chrome it might look a bit cheesy.