Engine Parts 2.5L 151cui GM "Iron Duke" Jeep CJ7
Replacement parts for the Iron Duke four-cylinder (1980-1983) – mounts, gasket set and hardware.
Why the GM Iron Duke in the Jeep CJ7 Needs Attention After Four Decades.
When AMC needed an economical base engine for the CJ7 in the 1980 model year, General Motors' 151 cui four-cylinder joined the line-up – the "Iron Duke", familiar from countless GM models and notorious for its hefty cast-iron block. It stayed on offer until 1983, paired with the SR4 four-speed gearbox, before the AMC four-cylinder took its place. That short production window is exactly what makes parts supply demanding today. The weak points show up less in the block itself than around it: motor mounts sag under the weight and let the engine move, head and intake gaskets harden and start to weep, connecting rod bolts lose their clamping force after repeated assembly, and the pilot bearing in the crankshaft runs dry once the clutch develops play.
From Engine Mounts to Pilot Bearing: The Parts We Keep on the Shelf
- Gaskets for head and intake: The upper engine gasket set for the GM engine covers cylinder head, intake and exhaust manifold and valve cover in one kit – the basis of any head overhaul.
- Connecting rod hardware: With the bottom end open, rod bolts and the matching rod nuts should always be replaced rather than torqued down a second time.
- Engine mounting: The motor mount for left or right absorbs vibration and holds the block in place – torn mounts are among the most common causes of driveline and exhaust trouble.
- Transmission and transfer case support: At the rear, the transmission mount carries the driveline, while on the Dana 300 the insulator bushing and its mounting stud secure the torque support.
- Clutch and oil service: The pilot bearing for the SR4 transmission belongs in every clutch job, and the matching oil filter takes care of routine servicing.
Crown and Omix: Two American Sources for Ageing Jeep Model Lines.
Most of these parts come from Crown Automotive – the Massachusetts specialist has spent decades supplying Jeep model lines that no one builds original parts for any more. The gasket set for the GM engine is supplied by Omix, another US manufacturer focused on classic CJ models. Both work to OEM specification, so fit and materials match the original.
We Help When GM and AMC Parts Become Hard to Tell Apart.
On early-eighties CJ7s the GM and AMC four-cylinders sit very close together – many bolt-on parts look alike but fit only one of the two. Send us the model year and engine number and we will sort out which is which, give you torque figures for rod bolts and cylinder head, and tell you the correct sequence for a head gasket job. Orders leave the warehouse in Germany as quickly as possible once payment clears.