Twin carburetor cylinder heads are common place with the popularity of BSA unit twin models, like the Lightning Kirk is on now, or the likes of Spitfires, hornets, etc., but nearly unheard of in the pre-unit series.
Two problems exist with this head. 1) It's deplorable condition. (Like, what is scrap aluminum going for right now? ) 2) Manifolds for it exist only if you're able to time travel back to your local BSA shop and hope they'll order a set for you from Nutley, NJ., where the BSA/Ariel East Coast warehouse existed.
So, what to do...
Solution 1) Have the head fixed by our friend, and very well-respected machinist, Ed Johnson from JVE. It will take all the talent in the world to fix this head, and, luckily for me, that's only 3.2 miles away. Seat repair, fin repair, resurfacing, port smoothing–it needs it all.
Solution 2) New manifolds have actually been made from wax molds and only need to be cut in half and taped to make 1 left and 1 right side manifold which are unique from one another. Ed is the man for the job again.
Either way, it's a good thing we have Ed. This is the kind of part you get completely rebuilt and ready to go, and just wait for that perfect BSA pre-unit twin to come in the door. It's kinda like finding the most perfect sunglasses in London, and you know you won't need them for a long time but better grab them for when you do. I'll post on the progress.