I managed to accumulate some 8x10 of J&C 400, and would like to hear if anybody has a recommendation as to developer. The Massive Dev. Chart says it is 'like HP5', then goes on to list what to do with developers.
The box has a tiny label that says Adox 400. The big label says J&C Classic 400 . It has different notches than Efke, which gives me pause about thinking it behaves like Efke.
J&C Classic 400 was Fortepan 400. I found it was more like Tri-X than HP5+. If you use Tri-X, you can use the same development times as a starting point. I've even processed mixed batches of Classic 400 with Tri-X and they've come out fine.
Efke never made an ISO 400 film, so Adox 400 would not have ever been Efke.
Adox does market an ISO 400 b/w film, which they "claim" is made for them by Ilford and can be processed just like HP5+. However this is only available in 35mm and 120 roll formats.