I was looking for a new engine to replace my worn out 250k+ mile 258 and have only been able to find running Jeep CJ 4.2L's hanging around. My question is if these will bolt in place of our 258's, and if so, which years? Or do they all bolt up? The main thing I am worrying about is that dang front axle mounting area.
If I remember correctly all Jeep 6 cylinders up until sometime in the 90's or early 2000's have the bosses for mounting the axle, but they don't have the holes drilled and threaded which you would have to do yourself. I expect someone who knows better will say so shortly.
Quote from: carguy87 on March 17, 2011, 12:17:12 PM
I was looking for a new engine to replace my worn out 250k+ mile 258 and have only been able to find running Jeep CJ 4.2L's hanging around. My question is if these will bolt in place of our 258's, and if so, which years? Or do they all bolt up? The main thing I am worrying about is that dang front axle mounting area.
What is your budget? I assume you want rebuilt or a drop in from another vehicle?
Most are drilled and tapped. Haven't seen or heard of one that wasn't. However any amc 6 79 or older does nothave an axle mountability.
So l6 4.0 and 4.2 works.
I was looking at rebuild, but I just wanna do a drop in as my budget is rather low atm, just have a few hundred to get this vehicle back on the road as the dist. drive gear on my truck stripped out after 250,000 hard miles. I will be using the old engine to probably make a stroker out of or drop a 4.0 head on it, .030 over pistons, fuel injection, and a 4.0 Camshaft for a nice little torquer.
All Jeep 4.2 (258) engines from 1980 and on will fit in your Eagle. You may need to change the exhaust manifold and reuse your Eagle oil pan, oil pump assembly in the non Eagle engine. So, don't discard your Eagle engine until the swap is done. The next best almost bolt in replacement is a Jeep 4.0 -- which is still an AMC designed engine and is the last incarnation of the AMC 7 main bearing inline 6's that debuted during the 1965 model year.
I found a 1989 4.2L from a YJ sitting around in some barn for $100. The engine only had 68k miles on it and has been sitting about a year, but has great compression and will be going into the Eagle this week. Only thing I didn't like was it came with the same feedback carb I am trying to get rid of.
NICE FIND! Good job! Can't wait for further updates!