The Birmingham age-herald., 1920-07-18

it gives gravity feed, thereby eliminating the weight of extra piping and of the feed pump, and that it makes the car- buretor much more accessible. l Another change has been in providing two inlet and two exhaust valves per cyl finder, instead of one The result has been bigger and steadier flow of gas to the cylinders, and a very high mean effective pressure even at great speed. A double finger valve lift is used, and this permits changes in the cam shart ana rocker arm mechanism which make this engine much superior to any predecessor ! in the troublesome matter of leakage from the cam shaft housing.
 ONLY ONE CARBURETOR l A third change is in the use Of single duplex carburetor, instead of the usual | two carburetors The difficulty of sym chronizing the throttle and altitude con- i trols of two carburetors has always been bugbear to aviators, but it had been felt that two or more were neces- l sary to give the requisite flow of gas. It | has been found in the tests. however. that this single duplex gives splendid re- suits in power output. gasoline economy.. ] and other details. which in the opinion of Colonel Vincent fully Justify the de-
 
 become universal practice with aero | plane engineers.
 ! The engine, of course. is equipped with ! the. Packard fuelizer which means perfect combustion of even poor quality gaso- line. This also greatly increases safety. since one of the aviator's dangers has al- ways been that it was often impossible to start an engine after it had been cooled by a long dive, and many bad landings have resulted. This danger is entirely eliminated by the fuelizer. In other respects the engine shows few changes from the established Packard design, and it is in fact intended to com plete that company's series of three en- zines which will meet all normal avia- tion demands. This engine is believed to be the biggest that will be practical for normal use.
 TECHNICAL DETAILS The main technical details are as fol- lcws The engine is of 12 cylinders. of the individual steel type which was de- veloped by Packard engineers working under Colonel Vincent before the war. and was contributed to the Liberty mo- tor. These cylinders are now generally recognized as the best type known, hav- ing the best water circulation. and there fore the best cylinder cooling. This prac- tically eliminates all valve trouble. The cylinder groups of six are set at an in- cluded angle of 60 degrees, and they arc of 5A-inch bore and 61A-inch stroke. The compression ratio is 20 per cent The total piston displacement is 2,o25 cubic inches, from which the engine takes it's name of Packard 2025.'' Yhe weight dry is LIS pounds. or 1.94 pounds per horse power, and the weight with radiator and water is 135s pounds. or 2.275 per horse power. Great pains have been taken with the placing of the parts and as a result this is believed to be the most accessible engine yet developed.
 The remarkable accuracy and balance of the design is shown by the fact that the engine went through it's tests just as lit came from the assembly department. without any changes or adjustments ex- cept in setting the carburetor. At the conclusion of the tests it was disassem- bled and gone over with the utmost care. and every part was found to be in ex- cellent condition. These tests were so successful that when the engine was taken to the flying field for further ground tests the engineers there decided that these were unnecessary. and .ne engine was at once installed in the plane.
 The tests showed that the engine has remarkable flexibility, great smoothness. especially at high speeds and that 1t is very light considering it's power. It developed 400 horse power at 1,265 reyolu- tions a minute, 800 horse power at 1870 g minute and 5S5 at 1895 revolutions