78 vs 83 4.2l engine

[dtrojcak]

What, if anything, is different on these two year model's engines?
I have a 78 jeep CJ7 with a AMC 258 i6 / 4.2l /AMC 258 i6 / 4.2l I6 engine.
I have come across someone selling a running 83 AMC 258 i6 / 4.2l /AMC 258 i6 / 4.2l engine with power steering pump and new alternator for $300.
I'm wanting to buy it for spare parts and/or engine swap, but wanted to make sure it would easily fit my jeep and the parts were interchangeable.
He swapped a 4bt diesel in his jeep and this engine was running when he pulled it out.

 

[Petescj]

Their pretty much the same engine. A couple things I can think of are different though. The carb on the 83 will be a Carter BBD. Throw it away. It was a "stepper" carb and was controlled by a small computer under the dash. The 83 will also have a plastic valve cover. I believe the head casting may be different as well to accommodate the different style cover. The 83 will have more emission stuff on it such as an air pump and an air tube system if it hasn't been removed. The exhaust manifold will bolt up the same but you'll have to use plugs for the air tube holes. The power steering pump on the 83 will use different style power steering lines than the other. The 83 uses a o ring style line as opposed to the early flange style.

 

[Bent]

The 78 will have the heavier 12 counter weight crankshaft. The 83 will have the 4 counter weight crank.

 

[Posi]

The 83 is computer controlled and the 78 is not. It won't make a difference on the installation but if both engines have stock carbs you'll need to swap over the 78 carb.

The HP and torque is similar 78 at 110/195 the 83 at 112/210. The 78 is a heavier engine by about 50-60 lbs as well. AMC went from a cast iron intake that was bolted to the exhaust manifold to an aluminum intake and separate cast iron exhaust manifold. They also changed to a lighter crank with fewer counterweights along with smaller headbolts (7/16" - 1/2")