The 151 (2.5L) inline 4 engine was used in '80-'83 CJs including
the CJ-8, CJ-7, and CJ-5. The 151 is often called the "Iron Duke", but
is actually a Pontiac engine designed to replace the Chevy "Iron Duke"
I4 engine. The engine does have the Chevy bell housing bolt pattern
though. The engine is manufactured by GM and uses a cast iron block
and cylinder head with hydraulic lifters and 5 main bearings. The 151
certainly is not a screamer, the AMC I4 has much better HP and torque
ratings.
The neat part about the engine is it has the same bell housing bolt
pattern as a Chevy small block. The bell housing makes a great low
buck Jeep to Chevy adapter since it is basically Jeep on the
transmission side and Chevy on the engine side. A regular Chevy bell
housing will bolt to the 151, so if you plan a transmission swap, a
Chevy transmission would be the way to go. Also, a Chevy 305 or 350
will bolt right to the Iron duke bell housing. The down side of
dropping in a V8 is most transmissions used with the Iron Duke are
light weight units.
The GM 151 has the intake and exhaust manifolds on opposite sides
of the cylinder head, but the AMC 150 has the intake and exhaust
manifolds on the same side of the cylinder head. The picture at the
top of the page is the passenger side with the intake manifold and
carb. The drivers side is pictured below with the exhaust manifold
removed.
| GM 151 |
| Bore x Stroke |
4.00" x 3.00" |
| Displacement |
151 ci(2.5L) |
| Compression Ratio |
8.2:1 |
| Horsepower (net) |
82@4000 |
| Torque (net) |
125@2600 |
| Main Bearings |
5 |
| Valve Configuration |
OHV |
| Fuel |
Rochester staged 2bbl |
Contributors
Thanks to David Ewing for the manifold identification tip. Thanks
to Ed Lowe for keeping my GM engine history straight.
Onboard
Air
Home-built
Serious Skid-Plate protection for the Oil Pan for under 20
bucks!
