Engines of the Golden Era – Ohlsson & Rice

OHLSSON & RICE ENGINES are the product of the world’s largest manufacturers of miniature aircraft engines and are designed expressly for and intended to be used in model aircraft operation only. Every part of the finished engine has been inspected and tested, and a Warranty Card is included with each engine.

It is of the utmost importance that you fill out your Warranty Card and return it to the factory for registration. KEEP A RECORD of your serial number, so that in the event your engine is lost or stolen, we can assist you in proving your ownership.

To secure the best performance and efficiency from your Ohlsson & Rice Engine it is important to study carefully the instructions in this folder and be sure they are thoroughly understood before operating the engine.

An important feature of Ohlsson & Rice Engines is their one-piece construction. Cylinders are secured to the crank-case, using special factory equipment, and can only be removed and replaced at the factory or authorized factory service stations. Do not attempt to remove the cylinder from the crankcase, as it will damage the engine.

In the side port engine, the intake tube is also an integral part of the crankcase and cannot be removed.


he danger of using some of the so-called “hot fuels” on the market makes it necessary for the factory to specifically recommend, as a safe and efficient fuel mixture, three parts gasoline to one part SAE 70 lubricating oil, with castor oil being injected into the intake tube during the break-in period.


The ignition system is a most important part of your engine. To hook it up, follow the wiring diagram, using only well-insulated (not enameled), stranded copper wire. The coil operates on three volts. When the ignition is all hooked up, check the spark by removing the lead from the spark plug, and hold it Va inch from the crankcase. Now turn the prop over quickly. A spark should jump from the terminal to the crankcase every time the prop is rotated. If so, replace the wire on the plug and the engine is ready to start.


From the closed position, open the needle valve from four to six complete turns. Place the timer control arm so that the stationary point (the nut on the timer housing) is advanced from the center line of the engine. With the ignition on and the timer set in the proper position, snap the prop over in a counter-clockwise direction and at the same instant place the left index finger over the intake tube, thereby choking the engine. After several turns, remove finger and crank over to start. Care should be exercised not to choke the engine excessively. This is particularly true with the type of fuel admission on the rotary valve engine. If the engine becomes flooded, close the needle valve and crank the engine until the excess mixture is forced out.

After the engine starts, advance the timer control arm and turn down the needle valve so that the engine runs smoothly. After a little practice, the correct spark and needle valve setting for easy starting will be second nature to you.

Use common horse-sense — operate your engine with good ventilation around you, as it is an internal combustion engine.


As each O & R Engine has been expertly assembled and tested before shipping, block testing is not necessary, and the engine will receive more adequate cooling in flight. However, it is recommended that the engine be broken in carefully when first installed in the model. Caution should be exercised and the engine not run -wide open”, for at least a period of two and a half hours. Do not run the engine faster than 3/4 throttle during the breaking-in period, as excessive heat may cause the piston to freeze in the cylinder or do other damage to closely working parts, resulting in delay and costly repairs. During this period the needle valve should be allowed to set on the rich (open) side to insure a rich mixture that will adequately lubricate all mov-ing parts, and it is advisable to inject a few drops of castor oil into the intake tube, while warming up the engine, to assist in lubrication.


If your engine fails to start, CHECK the following items: A broken or loose connection; fouled or dirty spark plug; exhausted batteries; ignition points not making contact; needle valve body fouled; out of gas; improper fuel mixture; flooded engine; metallic coil mounting or improperly grounded condenser.

CHECK your ignition circuit against the wiring diagram and be sure all the connections are secure.

CHECK the spark by opening the ignition points. Move the prop so that the piston is at the bottom of the stroke. The points are now open. With the ignition on, complete the circuit by grounding the stationary point against the timer housing. Each time you complete the circuit, a spark should jump between the gap and the point of contact. If the ignition points are not making proper contact, remove them from the timer housing and clean, or hone them on an emery stone. After cleaning. replace the points. The gap should be .005 to .010.

CHECK the spark plug by removing the plug from the cylinder, using a box or socket wrench. With the hi-tension lead attached to the plug terminal, the metal base of the spark plug grounded against the engine, and the ignition on, rotate the prop. Spark should occur across the gap with each revolution of the prop. (However, this does NOT necessarily mean- that the spark plug is not at fault, since it is not firing under compression.)


To obtain the maximum efficiency and performance from your Ohlsson & Rice Engine, the choice of propeller is important. There are many variables in choosing the proper propeller to get the utmost efficiency, but the following sizes come within the range for general use

For O & R “19” Engine—Free Flight-9 in. 4 pitch U-Control —8 in. 6 pitch

For O & R “23” Engine—Free Flight-10 in. 4 pitch U-Control-8 to 9 in. 6 pitch

For 0 & R “60” Engine—Free Flight-13 to 14 in. 4 to 6 pitch U-Control —10 in. 8 pitch to 12 in. 6 pitch