The Jeep Gladiator pickup ran for a quarter century with the same basic body, but the Jeep Gladiator engines kept changing. Kaiser launched the truck with an overhead-cam six of its own, then borrowed from AMC and Buick. After AMC bought Jeep in 1970, the options turned all-AMC, up to a 401-cubic-inch V8.
Here are the eight Jeep Gladiator engines, in the order they arrived. Sources disagree on some start and end years, so this list gives a year only where the references line up, and says so where they don’t.
1. Tornado 230 overhead-cam six, the first of the Jeep Gladiator engines
The Gladiator arrived in the fall of 1962 as a 1963 model. When Kaiser introduced it alongside the Wagoneer, the only engine on offer was the Tornado overhead-cam six. According to Offroaders.com, its single overhead camshaft had six lobes, with one lobe working both valves of each cylinder.
In all, the Tornado displaced 230 cubic inches, or 3.76 liters. In standard form it made 140 hp at 4,000 rpm and 210 lb-ft at 1,750 rpm, according to Offroaders.com’s engine file. That site and Old Cars Weekly both call it the first U.S.-designed, mass-produced overhead-cam engine. However, Old Cars Weekly also says it developed a reputation for oil leaks. Jeep dropped it from U.S. civilian vehicles in 1965, though production carried on in Argentina.
2. AMC 232 six
The Tornado’s replacement came from outside Kaiser. In the middle of the 1965 model year, Old Cars Weekly reports, AMC’s brand-new overhead-valve 232-cubic-inch six took over, rated at 145 hp.
That made it a small step up in power from the Tornado, with simpler pushrod hardware. Writing at The Truth About Cars, Paul Niedermeyer called it the “excellent new 232 six from AMC.” Meanwhile, the full-size Jeep engine table at Wagoneers.com lists it as the 3.8-liter “232 High Torque.”
3. AMC 327 Vigilante V8
For 1965, the Gladiator got its first V8. Old Cars Weekly says AMC’s 327-cubic-inch V8 made 250 hp. Jalopnik also says Kaiser began fitting it partway through the 1965 model year, in both the Wagoneer and the J-trucks.
The Wagoneers.com engine table calls it the 327 Vigilante and gives 5.36 liters. Citing Ackerson’s book JEEP: The 50 Year History, it lists 250 hp at 4,700 rpm and 340 lb-ft at 2,600 rpm. The end date is less certain, because Niedermeyer lists the 327 for the 1965 and 1966 model years only. In contrast, Wagoneers.com and Quadratec both carry it through 1968.
4. Buick 350 Dauntless V8
After that, Kaiser turned to Buick for its V8. According to Old Cars Weekly, the 350-cubic-inch “Dauntless V-8” became an option beginning in 1967, rated at 230 hp. Niedermeyer also dates its arrival to 1967.
However, other references disagree. The Wagoneers.com table lists the Dauntless for 1969 and 1970, and Jalopnik places it in 1968–1971 Gladiators and Wagoneers. Still, Jalopnik agrees on 230 hp and adds 350 lb-ft of torque. Old Cars Weekly’s featured truck, an unrestored 1969 J-3000 4×4, carries this engine.
5. AMC 258 six
Once AMC acquired Jeep in 1970, it was eager to fit its own engines, Niedermeyer writes. So the Buick V8 went out, and the AMC 258 six came in alongside three AMC V8s. Wagoneers.com lists the 4.2-liter 258 from 1971 through 1986.
As it turned out, the six outlived the Gladiator name. Jeep’s own history says the trucks dropped that name in 1971, and in 1974 they became the J-10 and J-20. For example, Hagerty’s valuation guide lists the 1977 J-10 Honcho with a 258 rated at 110 hp, on a one-barrel carburetor. Niedermeyer names the torque-rich six as one of the two most common engines.
6. AMC 304 V8
Of the AMC V8s offered in the trucks, the 304 was the smallest. Jalopnik credits the version used in the Wagoneer and J-Series trucks with 210 hp and 310 lb-ft.
Its years in the pickups are harder to pin down. The Wagoneers.com table lists the 304 only for 1971 and 1972. On the other hand, the Quadratec engine guide lists it in pickups across the 1970s and 1980s. Because of that conflict, this list gives no end year.
7. AMC 360 V8
Later, the 360 arrived in 1971 in J-series pickups and Wagoneers, according to Offroaders.com, which lists it at 5.89 liters. For 1971 it gives 245 hp at 4,400 rpm and 365 lb-ft, which the site takes to be gross ratings.
The numbers dropped once ratings changed. Then Offroaders.com lists 175 hp net at 4,000 rpm for the 1972 two-barrel engine. With the optional four-barrel for 1973, it lists 195 hp at 4,400 rpm. Niedermeyer calls the “not-too-big, not-too-small” 360 the most common V8 in the trucks.
8. AMC 401 V8
At the top of the range sat AMC’s 401, a 6.6-liter V8. Silodrome rates it at 225 hp and 320 lb-ft in a 1978 J10 Golden Eagle. Likewise, the Wagoneers.com table lists 320 lb-ft at 2,800 rpm for the big V8.
Still, both sources agree the 401 bowed out after 1978. That was also the trucks’ peak, when Jeep sold some 20,000 of them during the late-1970s four-wheel-drive boom, Niedermeyer writes. Finally, production of the J-series pickups ended in 1987.
More from Fast Lane Only
