Some big differences between Brit merlin & Packard one.
The Packard Motor Car Company undertook the latter and it was this version that was to power the legendary North American Mustang. However, unrecognized by many are the huge differences in the Packard built version. Packard manufactured some 57,000 Merlin engines, over a third of all Merlin production. From its earliest version the Merlin was clearly a precision, hand built work of engineering art constructed by some of the best British engineers. Even in its infancy the powerplant was built in small lots and had a string of design changes incorporated in an effort to squeeze performance and increase reliability in combat situations. The setback was this was not an engine designed for mass production, so in 1940, when the British Government turned to Packard for help with production of the Merlin some provisions had to be made.
In June 1940, Packard was requested to undertake the production of some 9000 Merlin XX engines. It took just three days for the company to respond positively but on that proviso that some modifications would be made to the powerplant to enable American accessories such as carburetors, fuel and vacuum pumps to be utilized. Packard then began the monumental task of organizing an engineering group to handle drawings and redesign for American production. In parallel Packard organized U.S. sources for carburetors, magnetos, spark plugs, and other accessories. Packard assigned some 200 personnel to the project and this included the draughtsmen who would undertake complete revisions of production drawings. At the outset the Packard engineers ran into problems, generally due to the fact that the engine was not designed for mass production. That the project was completed at all is testament to the determination and skill of those assigned the task.
