The Rudge Python Engine, Page 1
The Rudge Python Engine, Page 3
The Rudge Python 350cc Engine, Fig. 1
The Rudge Python Engine, Page 4
The Rudge Python 500cc Engine, Fig. 4
The Rudge Python Engine, Page 5
THE Python is a nearly "square" engine having a bore and stroke of 85 mm. x 88 mm. giving a capacity of 499 c.c. Steel flywheels are used in the built up crank-shaft assembly which runs on a single roller bearing on the timing side and large roller and ball bearings on the drive side: the crankcase being substantially thickened to give rigidity at this important point.
The cast iron cylinder barrel is secured to the crank case by six studs while five more retain the detachable cast iron cylinder head. A two ring aluminium alloy piston has a fully floating gudgeon pin bearing direct both on the piston and small end of the H section steel connecting rod. Brass end pads prevent the gudgeon pin from scoring the cylinder walls. Positively lubricated caged roller bearings are employed for the big end. Two overhead solid inlet and two overhead hollow exhaust valves are used, each having duplex valve springs retained by split conical collars.
The overhead rockers are carried on roller bearings mounted in hardened rings inserted in pillars cast on the cylinder head and are operated by internal rockers, tappets and push rods totally enclosed in oil tight cases.
Provision is made for fitting a flange type carburetter while the two wide angle radial exhaust ports are adaptable for either 1¾" or 1½" internal fitting exhaust pipes. 1¾" pipes may be fitted for the sake of appearance, but 1½" improve the performance. Provision is made for ignition by high tension magneto mounted behind the cylinder and driven by chain from the cam shaft running at half engine speed. A seating for a separate dynamo is provided at the front of the crankcase and driving sprocket on left hand axle is fitted.
A duplex plunger oil pump is located in the bottom portion of the timing case, and is driven off the right hand axle. Oil is drawn from the tank and forced by one end of the duplex pump past a tell tale and through a spring loaded gland into a hollow crank-shaft, drilled flywheel and so to the big end whence it is splashed over the inside of the engine and into the timing case.
One seventh of this supply is by-passed and led by an external pipe to the back of the cylinder where it lubricates the working face of the piston direct.
Surplus oil is flung round by the flywheels and collected by a scraper into a sump at the back of the crank case whence it is drawn through the opposite end of the pump and returned to the tank.
Over lubrication is prevented by having the exhaust side of the pump of a greater capacity than the delivery.
The sports Python engine has a special cylinder head with a central sparking plug, a larger choke carburetter and racing cam, while the compression ratio is higher than on the standard engine. This engine should be run on a 50/50 benzole mixture
THE valve timing for the 500 c.c. is measured with 020" clearance between the valves and rockers. The 350 c.c. gives the same timing with .017" clearance.
Timing as follows:—
Exhaust Opens - 14.4 mm. before bottom.
Closes - 2.4 mm. after top.
The ignition timing is 12-14 mm. before top with magneto fully advanced, both for 350 c.c. and 500 c.c. engines.
Rudge built Python engines which they supplied to numerous other manufacturers including:
Rudge Python Engine Types
Python engines were made available to other manufacturers in 1930.
249cc Python: Radial 4-valve head, aluminium piston, roller bearing big-end and mains.
348cc Python: 70mm by 90.5mm
499cc Python: 85mm by 88mm, radial 4-valve head.
175cc Python (not marketed in Great Britain)
Sources: Cycle Memory, et al.
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