The start of the ‘60s was when the passenger car horsepower races got hot and heavy, but not many car guys know the same thing was happening with tractors. The difference was farmers needed the power to get their work done faster and more efficiently. The car guys just wanted it. Well, so did the farmers – they just had better justification.
Oliver’s 1960 introduction to the realm of increased horsepower came with the four-digit series of tractors, which were in many ways just a rehash of the late ‘50s era gear. (That may sound dismissive until you consider their ‘50s era tractors were a bit ahead of the competition.) John Deere and International’s “All-New!” six-cylinder tractors were somewhat blunted by Oliver’s “25 Years of Six-Cylinder Power” ad campaign.
The 1800 and 1900 models came first in ’60, then the 1600 in ’62. Four-wheel drive versions of the 1800 and 1900 debuted for ’62, along with revisions for all the tractors that were dubbed the Series Bs. A four-wheel 1600 came in ’64. Oliver had used diesels as far back as 1948, starting with the inline 4-stroke sixes from Waukesha. These were good, economical diesels that used the Lanova Power Cell but they weren’t high power engines. When Oliver decided to tap the high-horsepower diesel market, they went with GM’s 2-stroke diesels.
“When Oliver decided to tap the high horsepower diesel market, they went with GM’s 2-stroke diesels.”
The first GM-powered Ollie was the ‘54 Super 99 GM, which used a 3-71. The ’58-61 990 GM and 995 GM also used the 3-71, but enhanced it to extract a few more ponies. For 1960, the “Big-Dog” Oliver 1900 went with the GM 4-53, which had a similar total displacement as the 3-71, but used four cylinders of 53 cubic inches each to make a 212 ci displacement (versus using three 71 ci cylinders for 213 ci.) If you didn’t know GM’s whiz-bang method for engine designation, now you do!
The GM 53 Series, 2-stroke diesels appeared in late 1958 as an evolution of the similar 51 Series that had debuted a few years earlier. Like their earlier brethren and the original 71 Series that dated back to 1938, these tractors were naturally aspirated, loop-scavenged, 2-stroke diesels that were modular and came in two, three, and four-cylinder inline configurations. The 53 series added Vee configurations as well, including 6V, 8V and even a few 12V engines. The 53 Series became as respected as the legendary 71 Series and lived on to the end of the 2-strokes in the mid 1990s, when they died from not being emissions-friendly enough.
The 4-53 came with 2-valve or 4-valve heads. The 4-valve heads could generate more power in the applications where it was needed due to the increased ability to vacate exhaust gasses. We could not determine 100 percent whether the Olivers used 2-or 4-valve heads, but 4-valves were better at keeping EGT down with high loads, and that seems the likely choice. Remember, there are no intake valves on a GM 2-stroke and the air comes from the blower via ports in the cylinder liner. The valves are only used for exhaust. The blower is constantly pushing air, so with the exhaust valves open and the intake ports exposed by the piston at BDC, the cylinder is cleared rapidly.
The early 1900s used a first generation 4-53 with a 17:1 compression ratio that made 89 PTO hp (about 100 flywheel). In ’62, with the 1900 B models, they upgraded to the 4-53N, which had a 21:1 compression ratio and, with other minor tweaks, developed a 100 PTO hp (about 108 hp flywheel) at the typical 2200 rpm tractor rating. With a 2800 rpm rating, as seen on many on-road or marine units, the 4-53N made 120 net hp at the flywheel.
By 1970, the GM (then called Detroit Diesel) 4-53 had a turbocharger (becoming the 4-53T) and was making around 140 hp for 2200 rpm applications like tractors and up to 170 hp with big injectors for road going equipment or marine applications. The GMs were gone from Oliver at this point, but there are old Ollie GMs with 4-53T retrofits.
In ’62, Oliver debuted a four-wheel drive option in both the 1800 and 1900 diesel tractors. These axles used planetary gears in the hubs, and there were several tire options to suit the operator. When comparing the Nebraska Test drawbar horsepower of a two versus a four-wheel drive 1900 (same PTO power), the four-wheeler comes out only a little ahead (about 5 hp). Comparing maximum drawbar pull, the four-wheeler was way ahead on the Nebraska tests, cranking out 16,991 lbs at full power (14.6 percent tire slip) versus 13,471 lbs at the same slip. Since the Nebraska drawbar tests were done on a concrete pad, the advantages of the extra driving wheels was not as apparent as it would be in the field, and the 4-by would have a huge advantage in dirt by being able to split the traction torque to four drivers rather than two. The four wheeler could also generate more pull with less wheel slip for better fuel economy, especially at high drawbar loads. Plus, with larger tires all around, it had better flotation on softer ground. It was an expensive option, usually about 30 percent more (a ’63 1900 with four wheel drive was about $13K), so it wasn’t purchased on a whim.
“The GM 2-stokes used unit injectors that generated their own pressure via the camshaft, and that’s why you don’t see injector lines or a pump.”
The standard transmission was a 6-speed mechanical unit, but an optional two-speed partial power shift doubled the gearing choices. The four-wheel drive was a part-time system with a single-speed, “in-or-out” control. Power steering was standard for the four-wheel drive with two hydraulic cylinders on the axle. Olivers were about average for the era in terms of driver comfort, with a suspended seat and a good control layout.
For 1965, the 1900 GM became the 1950 GM, with a few cosmetic and comfort improvements and a 5-hp boost in PTO power. Jimmy stopped screaming at Oliver in 1967, when the 1950-T tractor debuted with a turbocharged six-cylinder Waukesha 4-stroke that made 105 PTO hp (same as the last GM) from 310 ci and used a gallon-per-hour less fuel at the same output. The GM 2-strokes have earned endless respect for their high power output and reliability, but most farmers were not sad to see them go. On an open tractor, 10 hours of Jimmy screaming was enough to turn your brain to Jello. DW