So far, I have cut back the head Z/S ports to the main head block, made 8 holes for the 4 pairs of studs to attach the new manifold, made lots of prototype flanges with 32mm holes to attach the manifold to the head, made a 4 x 40mm hole 10mm thick ally flange to attach the 2 x 40 DCOEs, and now I am playing with my new lathe trying to make 4 x tapered tubes from 40mm to 32, to go between the Weber and the head flanges.
Cutting the tapered tubes on the lathe is only a challenge because I cannot yet find the right internal cutting tool to put in the lathe. Several ordered on eBay should be delivered for this weekend.
For a timing point of view, I reckon it takes 6 hours to machine the head and drill and tap the 8 stud holes, about 2 hours to make the 4 hole Weber flange, about 2 hours to make the 4 head flanges, about 4 hours to make the 4 tubes, and then the tubes need to be welded to the flanges on a jig, and then the ports and inlet tubes polished.
Total cost about £50 for the ally tube and plate, probably £100 for the polishing, about £50 for the welding, and a minimum 10 hours with the milling, drilling and lathe machine.
I am worried that the 1 & 2 ports will not match the 3 & 4 ports for air flow, due to the angles of the ports cast into the head, and the 2 40DCOEs will therefore need different jetting. Time alone will tell.
Is it worth it? Well, I either throw 7 Z/S heads away, sell them on eBay for not a lot, and but 7 Weber heads on eBay of varying quality and fault, or go down this route. Quite which is better, time alone will tell.
Will a 40 DCOE Federal head, with Federal cams, be much better than the Z/S head? I have no idea, but it should sound the part with the intake roar, and should be much easier to gas flow, and should have much more variation on the carb set up for various stages of tuning.
When the 4 tapered tubes are done, when I have the right internal cutting tool for the lathe, I will post photos of the parts ready for welding together.
Alex in Norfolk, with a garage full of ally swarf.