I have never seen a manual or parts list for any of the 1934-35 Douglases; all I have seen are sales brochures. It was a bumpy time for Douglas and I do not think they printed any more literature on the bikes then they absolutely had to, to get them sold. Would love to be proven wrong on that. Even the 1936-38 models only had parts list issued, the operating instructions being just a few typewritten sheets. Probably the best you can is to get the reprints of the parts list and manual for the S6 models (The London Douglas Motor Cycle Club has these) as the model Z is a direct descendant of these. That might be of some assistance with the engine, parts of which will have carried over. But there were changes. The 1934 models lost the oil sump and vane type oil pump of the S6, and instead kept the oil in a petrol tank compartment and used a gear type oil pump. The 1934 models used a Lucas Magdyno, which has a taller armature spindle height than the BTH M2 magneto the S6 models used. I have not seen a Z/Z1 apart, so cannot say what else inside they altered; if for example it still has the plain bearing on the timing side of the S6, or reverted to a ball bearing. No instructions on the 4-speed transmission were published, but there are posts here of the forum showing those apart. They are essentially the same as subsequently used on the heavyweight Aero models, unless you have the foot shift version which was discontinued after 1935.
-Doug
