Sideport vintage engines produced by Ohlsson & Rice company are the most popular and favoured by the modellers. The O&R company manufactured a wide range of these sparkies between 1936 and 1949. There were some variants introduced during the production. We will cover the most notable differences in the following article, which will help other engine collectors to identify their gems accordingly.
OHLSSON MINIATURE .56 – 1937 (late 1936)
Die-cast aluminium parts. Radial mount case. “OHLSSON” on 3 bolt front cover. Upright open timer. Cast 3-prong cam/drive washer. The cylinder assembly with pressed-on aluminum fins has a small mounting rim exposing two mounting screws. Manifold halves clamped with two bolts. Stamped aluminum stack. Cadmium-plated brass needle valve and cylindrical tank with screw-in cap. Drive washer #1, needle valve #1.
OHLSSON MINIATURE .56 – April 1937
As per the previous model except for the new cylinder with steel fins and mounting flange enlarged to match the top of the crankcase. Drive washer #1, needle valve #1.
OHLSSON MINIATURE .56 – mid 1937
As per previous model except for 2 added screws in manifolds. Screw heads fit in notches in the bypass half. Drive washer #1, needle valve #1.
OHLSSON GOLD SEAL .56 – January 1938
Cylinder, exhaust, needle valve and tank per previous model. New 4 lug bypass features Ohlsson name. Crankcase features beam mounts. Front cover has heavy rim and 6 webs. Propeller and drive washers, enclosed timer housing and arm are steel stampings. New shaft splined to fir 3 spot drive washer #2, needle valve #1.
OHLSSON GOLD SEAL .56 – April 1938
As previous model except for new deep bowl shaped plastic tank. Rimmed steel tank top with aluminium screw in filler cap. Later engines introduced 4 spot drive washer #3 and new needle valve and ratchet #2.
OHLSSON GOLD SEAL .56 – late 1938
As per previous model except for new flat bottom tank with sump similar to but larger than .23 type. Straight pickup tube, 4 spot drive washer #3, needle valve #2, tank top #3.
OHLSSON GOLD SEAL .56 – mid 1939
As per previous model except for new cylinder with straight taper fin profile. Aluminium timer parts introduced during this run.
OHLSSON GOLD SEAL .56 – May 1939
As per previous model but crankcase has an added web between rear face and cylinder mounting flange. Bulge added to front cover to incorporate ball thrust bearing. Drive washer #3, needle valve #2, tank top #3.
OHLSSON 60 CUSTOM .604 – March 1940
General design similar to .23 type. O&R “Eagle” on front of case. Black painted cylinder with 1/4″ plug. Cast venturi/tank top with jiffy fill. Plastic tank has 3 fingered steel support. Front cover has one thick web concealing an oil passage, aluminium main bearing, ball thrust plus roller bearing crankshaft support, 1/4″ propeller shaft. Initial production used stamped drive washer. Heavy knurled drive washer #5 and needle valve #4 introduced during this run.
OHLSSON 60 CUSTOM .604 – late 1940
As per previous model, but with 3/8″ plug. Bronze main bearing introduced. Drive washer #5, needle valve #4, tank top #6. NOTE: Many earlier Customs with 1/4″ plug reworked for 3/8″ plug.
OHLSSON 60 SPECIAL .604 – August 1941
Economy model based on 60 Custom parts. No roller bearing on shaft. No eagle on front of case. 60 stamped on aluminium weld seal. Unpainted cylinder. 3/8″ diameter intake tube. New scaled up version of 23 tank with tank top #7. 1/4″ shaft, drive washer #5, needle valve #4.
OHLSSON 60 CUSTOM .604 – late 1941
As per previous model, but with 5/16″ shaft. Drive washer #7, needle valve #4, tank top #6.
OHLSSON 60 SPECIAL .604 – late 1941
As per previous model except for 5/16″ shaft, drive washer #7, needle valve #4, tank top #7.
OHLSSON 60 SPECIAL .604 – January 1942
As per previous model, but cylinder is painted black. Drive washer #7, needle valve #4, tank top #7. NOTE: Production was briefly frozen because of war time restrictions. Temporary production resumed using remaining parts and eventually non essential materials. See following model 60. Drive washer #7, needle valve #4, tank top #7.
OHLSSON 60 SPECIAL .604 – wartime 1942
As per previous model, but quality and materials vary. Extreme examples will have thick cylinder fins, rough castings. Dull nickel plated brass intake tube, needle valve and ratchet, timer assembly cad plated steel. Some with smooth cad plated drive washer #8, some bare brass intake tubes. Needle valve #4, tank top #5.
O&R 60 SPECIAL .604 – October 1945 to October 1946
Similar to the January 1942 model, but early engines have bare brass intake tubes. Early 1946 engines have bright nickel plated brass intake tubes, late engines have aluminium. Weld seal has bullseye imprint. New drive washer with 8 radial ribs #8, needle valve #4, tank top #7.
O&R 60 SPECIAL .604 – October 1946
As per previous model except for new vertical web front cover. Aluminium intake tube. Drive washer #10, needle valve #4, tank top #7.
O&R 60 SPECIAL .604 – 1947
New radial mount crankcase with 10 heavy cooling fins on bottom. Large oval exhaust and 7/16″ diameter intake tube. 60 cast into case above weld plug. Early engines highly polished. Drive washer #10, needle valve #4, tank top #7.
O&R 60 SIDEPORT .604 – 1948
Based on 1947 engine, but beam mounts with holes rather than slots added to case casting. Drive washer #10, needle valve #4 & #5, tank top #7.
O&R 60 SIDEPORT .604 – late 1948
As per previous model except for new front cover with ball detent for projected new timer. Drive washer #4 and in mid-1949 #11, needle valve #5.
O&R 60 SIDEPORT .604 – January 1949
As per previous model, but cylinder now features a staked aluminium head. 1/4″ spark plug. Drive washer #7, needle valve #5. Not supplied with tank.
Resources:
- Engine Collectors’ Journal, issue 78, Feb. 1985
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