The Rich Tool Co., of Chicago, made the valves.
The Gibson Co., of Muskegon, Mich., made the springs.
The Packard Co. made all the patterns for the aluminum castings, which were produced by the General Aluminum & Brass Manufacturing Co., of Detroit.
The Packard Motor Car Co. used many of its own dies in order to obtain suitable drop forgings speedily, and also made all necessary new dies not made elsewhere.
As these various parts were turned out they were hurried to the tool room of the Packard Co., where the assembling of the model engines was in progress.
Before the models were built, however, extraordinary precautions had been taken to insure that the mechanism would be as perfect as American engineering skill could make it. The plans as developed were submitted to H. M. Crane, the engineer of the Simplex Motor Car Co. and of the Wright-Martin Aircraft Corporation, who had made a special study of aviation engines in Europe, and who for upward of a year had been working on the production of the Hispano-Suiza 150-horsepower engine in this country. He looked the plans over, and so did David Fergusson, chief engineer of the Pierce-Arrow Motor Car Co. Many other of the best experts in the country in the production of internal-combustion motors constructively criticized the plans, these including such men as Henry M. Leland and George H. Layng, of the Cadillac Motor Car Co., and F. F. Beall and Edward Roberts, of the Packard Car Co.
When the engineers were through, the practical production men were given their turn. The plane and engine builders examined the plans to make sure that each minute part was so designed as to make it most adaptable to quantity production. The scrutiny of the Liberty plans went back in the production scale even farther than this; for the actual builders of machine tools were called in to examine the specifications and to suggest modifications, if necessary, that would make the production of parts most feasible in machine tools either of existing types or of easiest manufacture.
Thus scrutinized and criticized, the plans of the engine were the best from every point of view which American industrial genius could produce in the time which was available. It was due to this exhaustive preliminary study that no radical changes were ever made in the original design. The Liberty engine was not the materialization of magic nor the product of any single individual or company, but it was a well-considered and carefully prepared design based on large practical aviation-engine experience.
On July 4, 1917, the first 8-cylinder liberty engine was delivered in Washington. This was less than six weeks after Messrs. Hall and Vincent drew the first line of their plans. The same procedure was even then being repeated in the case of the 12-cylinder engine. By the 25th day of August the model 12-cylinder liberty had successfully passed its 50-hour test. In this test its power ranged from 301 to 320 horsepower.