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Jeep Engine: AMC 258 I6

258 I6

 Jeep Engines 

287(4.7L) V8
360(5.9L) V8
318(5.2L) V8
242(4.0L) I6
150(2.5L) I4
173(2.8L) V6
GM 151 I4
AMC 401 V8
AMC 360 V8
AMC 304 V8
AMC 258 I6
AMC 232 I6
"Dauntless" 350 V8
"Dauntless" 225 V6
"Vigilante" 327 V8
"Tornado" 230 I6
Perkins 192 I4
"Hurricane" 226 I6
"Hurricane" 134 I4
"Go Devil" 134 I4

Engines

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General


The AMC 258 was introduced in 1971 in J-series pickups and Wagoneers and in 1972 in CJs. It continued to be used through 1990 in the Wrangler. It is basically a stroked 232 engine. The great thing about this engine is it reliable, inexpensive, and has horse power and toque peaks at low RPM.

The 258 inline 6 (I6) engine always came from the factory carbureted any many people complain about the Carter BBD carburetor and the maze of emmissions vacuum hoses. There are a couple articles below that can help you sort through those hoses and tune the Carter BBD. For a carbureted engine, the 258 with the Carter BBD performs very well off road. The 258 always came with a cast iron block and cylinder head, hydraulic lifters (with non-adjustable rockers), and 7 main bearings.

The 258 used in '87-'90 Wrangler YJs uses a computer controlled Carter BBD. It is very simlar to the 258 used in '82-'86 CJs, but performance suffers due to emmission controls.

AMC 258 I6
Bore x Stroke3.75" x 3.90"
Displacement258 (4.2L)
Compression Ratio9.2:1
Horsepower (net)112@3200
Torque (net)210@2000
Main Bearings7
Valve ConfigurationOHV
Fuel2bbl Carter BBD

The 258 used in '82-'86 CJs used a computer controled Carter BBD. The computer controls mixture based on an O2 sensor and other sensors.

AMC 258 I6
Bore x Stroke3.75" x 3.90"
Displacement258 (4.2L)
Compression Ratio9.2:1
Horsepower (net)115@3200
Torque (net)210@1800
Main Bearings7
Valve ConfigurationOHV
Fuel2bbl Carter BBD

The 258 used in '79-'81 CJs, some used a 1bbl carb and some used a 2bbl carb.

AMC 258 I6
Bore x Stroke3.75" x 3.90"
Displacement258 (4.2L)
Compression Ratio8.3:1
Horsepower (net)110@3500
Torque (net)195@2000
Main Bearings7
Valve ConfigurationOHV
Fuel1bbl and 2bbl

The 258 used in '72-'78 CJs, J-series pickups, and Wagoneers, some used a 1bbl carb and lower compression than later 258s.

AMC 258 I6
Bore x Stroke3.75" x 3.90"
Displacement258 (4.2L)
Compression Ratio8.0:1
Horsepower (net)110@3500
Torque (net)195@2000
Main Bearings7
Valve ConfigurationOHV
Fuel1bbl

The 258 was introduced in 1971 as the standard engine in J-series pickups and Wagoneers.

AMC 258 I6
Bore x Stroke3.75" x 3.90"
Displacement258 (4.2L)
Compression Ratio8.5:1
Horsepower (gross)150@3800
Torque (gross)240@1800
Main Bearings7
Valve ConfigurationOHV
Fuel1bbl Carter or Holley

Other Information

Learning to Love Your 258: An easy fix for the most common idle problems with the 258(4.2L) engine used in Wranglers(YJ) and CJs.

Contributors

Some photos courtesy Rick Boiros.

258 I6 side

Last modified Wednesday, 01-Dec-2010 08:33:42 MST


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Comments:

Allen (10/19/2011)
I have an 83 CJ-7 with the 4.2 liter 258. I replaced the Carter with the Holley 350 2bbl which comes factory jetted at 61 and uses a metering plate in the rear with no jets. Anyone know a good recommended jetting for this carb with my engine?

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