Mercedes M121 Petrol Engine Manuals
The Mercedes-Benz M121 petrol engine was produced from 1955-1968 in 4 versions: M121, M121 BI, M121 BII @ 1.9 L (1,897 cc) and M121 BIX @ 2.0 L (1,897 to 1,988 cc).
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Download: Mercedes Benz M121 Engine Manual
Mercedes
M121 Engine Service Repair Manual
Applications: W110, W120, W121, Unimog, L319 Trucks
Download: 64.3mb, 448 pages
Format: .pdf document
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$19.95
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M121 Technical Data
The Mercedes-Benz M121 engine is a single overhead camshaft inline four-cylinder motor introduced by Mercedes in 1955 and used in various series models during the 1950s and 1960s. It replaced the 1.8 liter M136, offering improved performance. The M121 motors were in production until 1967, when the M115 series engine took its place.
Applications
The M121 engine was first employed in the Mercedes Benz "Ponton" model 180, with 190, W110 "Fintail" 190c and 200 models featuring an updated version of the M121 with greater performance through variations in compression ratios and improved carburetion. Its use continued in trucks such as the Mercedes-Benz L319 and Unimog off-road models.
Variants
The base M121 engine featured a single chain driven overhead cam, staggered valves, cast iron cylinder block, 85 mm (3.35 in) cylinder bore, 83.6 mm (3.29 in) stroke, forged three ring crankshaft with a displacement of 1.9 L (1,897 cc) and 8.5:1 compression.
The M121 BI was employed in the W110 190 model and had an increase of 5 hp with top speed also increased to 93 mph from the original's 86 mph.
The M121 BII variant had a rating of 105 hp at 5500 RPM and 114 lb ft of torque at 4000 RPM with the top speed of 110 mph, and featured two parallel carburetors. It accelerated to 62 mph in 14.5 seconds making it the fastest engines of its day.
The M121 BIX displacement increased from 1.9 to 2.0 L (1,897 to 1,988 cc) with an increase in bore from 85 to 87 mm (3.35 to 3.43 in) and compression ratio increased to 9.0:1 which produced 95 hp at 5200 RPM and 114 lb.ft of torque at 3600 RPM. This engine used a new Solex 38PDSJ carburetor.
