[schwarze-man]

Thanks Sidney.
The engines are interesting to compare with regards to production, Merlin III / 601A. Both similar with regards to crank, blocks/heads (one piece), spur reduction gear, cam drives. However, purely from working on them both, I suspect there is a greater amount of man hours in the production of the 601A.
The 601 valve gear looks simpler with interposed roller followers but the Merlin rockers are simple cast sleeves with welded-on arms and follower pad. Hmm...
The 601 roller Big-ends certainly have a greater precision parts count and that leads on to the hydraulic supercharger drive with its controller pump and precision coupling, definitely more precision parts. The Fuel injection system compared to the SU carb? No contest, the SU does the job but, the Bosch injection system has a large parts count and, a great many of them are precision ground for matched fit.
Overall, I would expect that the complete 601A needed more hours than the Merlin III to build. Cheers

SM