fastmongrel
1st Sergeant
Is this the myth of British Merlins being hand fitted again?
It is my understanding that most British built Merlin components were interchangeable with US built versions. Basically except where there was a design difference, such as the supercharger drive on two stage engines.
Wasn't there even an example where the RAF broke down several Merlins so that the USAAF could use them for spare parts for their P-40F/Ls in Africa?
Life expired RR and Packard engines were broken down to provide parts for Rover built Meteor Tank engines when production outstripped parts supply. Mainly Cranks, Rods and Cylinder blocks. The Packard and RR parts were given the same Rover part number and used interchangeably. Derby engines from the MkXII onwards were sometimes hand fitted but that was because they were built in small batches for special needs or were early production prototypes. Merlin/V1650s from RR Crewe, Fords Manchester, Government engine factory Glasgow and Packards Detroit were interchangeable for all intents and purposes. Fittings and ancillaries might be different between British and US manufacture but all major parts were identical between similar models.
Packard built a small number of types in vast quantities over 3 and a bit years but RR Derby built dozens if not hundreds of different types over 20 years so modern day parts supply can be a problem if using RR parts. A 1955 Merlin 621 crank might not fit a 1936 Merlin G crankcase.