Olds Mechanical Engineers and Founders - Innovative Engineering Excellence

Olds Type "H" Marine Engines

Features and Specifications:  3-5 H.P. and 4-6 H.P.

Four cycle, Overhead Valves, self oiling, built-in Crank starting, replaceable wet sleeve ground finish bore, Detachable impulse magneto.

Crankshaft - Special hollow cast 1 5/8" diameter Journals, 1" diameter Crankpin
Bearings - Main: Full Circle Replaceable Sleeves (whitemetal)
                  Big End: Replaceable Steel-backed Shells.
Valves - Best obtainable. Exhaust valve of 21-4N type rustless steel.
Exhaust - Bronze water cooled manifold (standard) OR Optional dry exhaust system if required.
Carburettor - All bronze with metal float, own design and manufacture.
Water Pump - Plunger type, driven at half engine speed. Fitted with accessible Bronze ball valves.

Model 3-5 H.P. 4-6 H.P.
Bore x Stroke 3" x 3 1/8" 3" x 3"
Flywheel 9" dia. 4" wide, 42 lbs 10" dia. 4" wide, 57 lbs
Engine Weight 142 lbs 167 lbs
Overall height 22" 22"
front cover to rear of flywheel
12" 12"
Distance between bed timbers 8" 8"
Bolt Hole centres 10" x 3" 10" x 3"
Depth from centre of Crankshaft
Top of bed level with centre of crankshaft
5 5/8" 5 5/8"
Standard Propeller 11" dia. x 10" pitch 11" dia. x 10" pitch
Standard Shaft size " dia. " dia.
Normal speed 1200 to 1300 r.p.m. 1400 to 1500 r.p.m.
Fuel consumption 4 hours per gal. 3 hours per gal.

For further Enquiries, Contact Olds Engineering

The following notes are intended to assist you, the user, to obtain the best service from your engine. In general, the maintenance and care of your engine should be as in any other good four-cycle job. Here we mention a few points which do apply specifically to the 3-5 h.p., 4-6 h.p. "OLDS."

LUBRICATION: The life and endurance of any machine is probably most affected by its lubrication. We cannot stress too strongly that the service required from an oil used in small engines, particularly in open boats, is very severe. In recommending Castrol XL we sincerely believe we are naming an oil most suitable for the conditions encountered. Check oil level before attempting to start. Sump capacity is one quart. The oil level should not be raised above the flat on the dipstick. When adding a large quantity of oil, as when refilling after draining, the dipstick should be removed to allow the escape of air from the crankcase. It is a good policy, particularly with a new engine, to add a small quantity of oil, DAILY (about a teaspoonful) through the oil filler hole. At the same time the water pump should be oiled. It is necessary to only hand tighten the oil filler plug. In a new engine an upper cylinder lubricant should also be used with the fuel. The sump should be initially drained and refilled after approximately five hours running, and after that when necessary, depending on the condition and colour of oil. As a general guide the oil should be changed with every 12 gallons (approx.) of fuel used or every 40 to 50 hours running. A tray fitted under the engine can simplify the draining of the sump, and it will also protect the lower part of the crankcase from bilge water. Sump drain pumps are available for oil changing, these operate with the suction pipe fitted down through the dipstick hole. Enclosed cone clutches fitted to some models should be lubricated with a light oil or a mixture of oil and kerosene. The capacity is approximately one-third pint. Replaceable oil seals are fitted to the rear ends of both crank and cam shafts.

CARBURETTOR: Presence of fuel in the carburettor may be seen by the height of the float valve pin which protrudes through the cap of the float bowl. Starting when cold is made easy by depressing the float pin, thus flooding the carburettor. With mixture screw (numbered) opened about one-third of a turn and throttle slightly opened also, the engine should start readily. The mixture screw should be adjusted immediately to give the best running. In some cases the mixture screw is fitted with a lock-nut to prevent interference with this setting. The air valve spring adjusting screw will no doubt require adjustment at some time. This should be set so as to apply the very lightest spring pressure in holding the valve on its seat. Always fit a fuel filter trap in the line, especially where a fixed mixture setting is required. The height of the fuel tank above the carburettor should, if possible, not exceed more than 6" to 8". The use of super grade petrol is recommended.

TIMING: The camshaft in these engines is chain driven, and if for some reason the timing chain is removed, care should be taken to maintain correct timing upon replacement. Firstly, the cylinder head must be fitted, the camshaft in position and the tappets correctly adjusted. Turn the crankshaft to top dead centre position, which is indicated by the flywheel timing mark lining up with TDC (top dead centre) marked on the block casting. Now turn the camshaft in its running direction until the front rocker arm just tightens on the inlet valve. The chain can now be fitted and the timing checked. On top dead centre the inlet valve should be just commencing to open and the exhaust valve closing slightly after this.
A hole is provided in the flywheel for the purpose of applying a half-inch bar for turning the engine over slowly as is required when timing, and also for holding the engine when tightening or loosening the flywheel or propeller nut. The timing chain should be replaced if showing signs of wear. The magneto drive dog is pinned to the camshaft and its position is therefore fixed while this is so. With the impulse pawl disengaged, the magneto contact breaker point should open when the timing mark is approximately one inch before TDC. The impulse coupling not only gives a much stronger spark for starting but also gives a retarded spark which prevents any possibility of the engine kicking back. The impulse should release when the timing mark is just past TDC but should not be later than " past. The tappet clearance should be set at .010" and the spark plug gap at .028". The magneto breaker point should beset at .012"; wider points will advance the ignition timing slightly. The magneto fitted is normally the popular "Lucas S.R. 1" clockwise rotation, fitted with adjustable impulse coupling. Booklets covering the magneto are available on request.

WATER-COOLING: The block casting is fitted with a light press fitting centrifugal cast wet type sleeve. This can be removed for complete waterjacket cleaning. The sleeve is held in position by the cylinder head bearing on its top, while the bottom end is shouldered and fitted with a copper asbestos ring. When replaced in the block, the sleeve can be revolved a quarter of a turn to help give even cylinder wear. A clean-out drain hole is also provided at the base of the jacket. The very efficient plunger pump which works at half engine speed should not require a scoop of any description to assist it. The outlet water is mixed with the exhaust gas in the bronze manifold. This item is designed to be fitted with1" rubber hose for a complete exhaust or as a connection between it and suitable pipe. Care should be taken to ensure that the exhaust system has ample fall to drain completely. It is good practice, when leaving the engine standing over a period, to bring it up to compression, thus closing both valves and sealing the cylinder. Always remember to drain water jacket before removing cylinder head.

SHAFT CONNECTION: Always be sure that the engine and propeller shaft are in correct alignment. Failure to do so will result in loss of power and undue wear of shaft and bearings. The engine can be tilted to an angle of up to approximately 15 degrees. The propeller shaft coupling is arranged to serve as a flywheel puller. To apply firstly remove the three screws attaching the flange of the coupling to the flywheel and loosen the flywheel nut several turns; bring back the coupling into position when it should bear on the back of the flywheel nut. When the screws are replaced and tightened evenly, removal should be made easy. The propeller shaft need not be removed for this operation. To allow for any small error in alignment, a slight amount of flexibility in the shaft coupling can be arranged in engines currently in production. The three 3/8" screws attaching the flange to the flywheel in earlier models have been replaced by double ended studs screwed tightly into the flywheel and fitted with self locking nuts. The propeller shaft can be let bear on and transmit its thrust directly to the crankshaft, leaving the coupling approximately 1/16" clear of the flywheel face and with the securing nuts just clear of the flange. With this arrangement the flange can work slightly on the studs and flywheel spigot. Care should be taken not to install engine too far out of alignment as to do so will cause undue wear of the studs. The flywheel spigot and studs should be greased on assembly. The coupling can be made rigid by tightening up completely with the propeller shaft just clear of the crankshaft as in the earlier engines.
The propeller thrust is transmitted to the heavy duty ball thrust bearing located in the timing case on the front end of the crankshaft. Crankshaft end-play can be adjusted by shimming between the crankshaft timing wheel and the thrust bearing. To maintain correct clearances, where possible, use genuine replacement gaskets. Complete sets or individual gaskets are available at little cost.

Wm. Olds & Sons Pty. Ltd.
ABN 33 009 859 250
78-80 North Street, Maryborough Q, 4650 Australia
P.O. Box 3030, Pallas St. Post Office, Maryborough Q, 4650
Phone: 07 41213649  Fax: 07 41233590   www.olds.com.au
Innovative Engineering Excellence ~ Serving Since 1918