M.A.G. Engines for 1921. A New 90° V Twin and a Small Single, with Detail Improvements on all Models at Olympia.
AMONG the M.A.G. engines which will be at Olympia may be mentioned the small single-cylinder models which are not at present very well known in this country. As regards excellence of finish, design, and workmanship, they follow very closely the lines of the better known and larger twin-cylinder models.
The following improvements have been incorporated in all the engines exhibited: improved balance, a telescopic tube projecting the tappet rod which allows the tappet to be adjusted without interfering with the inlet dome, an improved inlet dome giving a freer passage to the mixture, larger radiating fins, and larger cams giving increased lift to the valves. These engines will be generally quieter, and yet will provide more power.
The Morgan engine will have the position of the bevel altered so that it may be more easily extracted. This will entail the fitting of a magneto running in a clockwise direction, but otherwise the standard specification is followed.
Quite a novelty is the 90° M.A.G. water-cooled cycle car engine, 82 mm. x 102.5 mm., 1,100 c.c. We have known for a long time that M.A.G. Engines, Ltd., have been experimenting with a forced lubrication system. This is now carried out by means of a plunger pump on the timing gear side of the engine, driven by means of a cam off the crankshaft, from which run three leads, one to the timing gear, and one to each crankshaft bearing.
Mechanical Lubrication on 90° Engine.
An ample supply of oil is carried in a large flat-based sump at the base of the crank case, into which it is introduced through a large filler cap. At the base of the sump is a glass window.
The magneto is mounted on a platform between the cylinders, and is driven by means of an enclosed chain from the mainshaft. The chain may be adjusted by slackening or tightening the nuts on the retaining bolts which serve to raise or lower the magneto from the platform.
Valve-operating mechanism follows M.A.G. principles throughout, but a new type of exhaust lifter has been introduced. The mechanism consists of two links connected by means of a small wheel to two cranks thereon. The action of pulling up the lever serves to raise the left-hand valve, and at the same time pulls round the wheel, causing a similar movement on the right-hand valve stem. A release valve is now supplied to the oil sump, which serves to return the oil thereto if the pressure is too great; this feature eliminates any danger to the pump driving mechanism.
In addition to the above, the range of M.A.G. engines exhibited will consist of the 2½ h.p.. 250 c.c., 64x77 mm.; 2¾ h.p., 300 c.c., 64x92 mm. (both these are single-cylinder models); the 3½ h.p., 500 c.c., 67x77 mm.; the 6 h.p., 750 c.c., 72x91 mm.; and the famous 8 h.p., 1,000 c.c., 82x94 mm.
The Motor Cycle November 25th, 1920. pp. 653-654