Anyway at this point the engine has to come out to put a new oil pump and pickup on it. While it’s out I’m going to clean it up and replace some other seals. 

I also found a donor 232 for basically free that I’m considering just swapping in instead of messing with the original engine.

So my questions are do you think it’s worth fussing with the original engine?

Should I just swap in the known good 232 and then rebuild/hop up the original 232?

I’d go with a different engine altogether but I don’t want to do any other driveline modifications because I don’t necessarily want to make this a “project”.

Oil pumps rarely wear out on these.

30-40 psi while driving is not bad on an old engine. How does it run?

Keep in mind that if you swap in a different motor, it has to be '71 or earlier, as there was a major change in '72 that would not be compatible with a '66 tranny/starter.

As far as 30-40 psi while driving is concerned, it’s not bad at all. I’m not concerned with that. It’s the 0-5psi and valve tap at idle that is concerning to me.  Today in traffic the valve chatter was awful. The engine otherwise runs fantastic. Feels strong and runs smooth.

I considered a heavier oil, I have 10w30 in it now. I’d like to know what the actual issue/fix is though. Did you ever figure out the issue?

Even with such low mileage you think it would be crank and bearings? I’m definitely not an engine guy but at 46k miles seems low to have bearing issues. Who knows though it could have not been well cared for.

Unless you know it's full history, it is far more likely that 46K miles is 146K, American cars having 5-digit odometers.

How are the plugs? Is it burning oil? Etc.

The 232 is a rugged beast, even if abused. It's also torquey and revs gladly (to 5K anyway) so you might not really need "more power", before you have a solid motor. All sorted out, good carb, good spark etc it will be pretty nice.

If you indeed have the gumption to swap and rebuild, I'd suggest rebuilding your freebie that's already out of the car, drive and tune what you've got, then out the rebuilt 232 in. Also make sure they're the same generation 232 -- starter on the left, mainly. After 71 they switched to the V8 bell pattern.

It could possibly be 146k but story goes the guy I got it from knew the original owner and confirmed it is actually 46k miles.

Either way the engine runs great. Plugs looked good when I changed them the other day. It doesn’t burn any oil and runs very smooth. I’ll switch to 20w50 and also do a compression test to see the health of the engine. I’d love to not have to pull this engine out.

Unless it's a quality oil pressure gauge,  it's readings might not be that accurate on the lower scale.

The gauge is not high quality lol I don’t trust it 100% but the low reading does correlate with the valve clatter so it is accurate in that sense. I plan on changing that also. Cold start/idle it will sit at like 5-10psi at idle. 

You guys are making me feel less worried about the oil pressure.

Look up Matt's Old Cars Head Bolt Modification.

If you remove the oil filler cap you should be able to see oil getting to the front rockers. 

I used to do the opposite; top-quality oil changed at max. recommended intervals. I don't think this is a bad approach, but I think old Esmond's 'frequent' method is visibly better.

I'm glad 20w-50 solved the short term problem. 

From the looks of it there is oil at the front rocker when looking through the oil cap.

See this: https://www.mattsoldcars.com/RestoreAmerican/boltmod.shtml" rel="nofollow - https://www.mattsoldcars.com/RestoreAmerican/boltmod.shtml

I'd check it and do the mod even if it looks good. Won't hurt, and will keep oil flowing to the rocker shaft. I don't know if AMC made that passage larger in later years or not.

I wouldn't be afraid to run 20W50 oil in warm weather, but not in cold. You can always mix the oil, like three quarts of 20W50 with two quarts of 10W30. I've run it in an old engine the other way around (2 of 20W50) year round. The additives in the oil control viscosity, mixing weights (or brands) isn't an issue.

If you spin off the filter and lay it on the side no oil should drain out of the outside holes. The filter should stay relatively full. When I removed the Wix or Napa filters oil would gush out of the outside holes.

I've had good luck with the Purolator L30005 and Delco filters. Heck, even the Fram ph11 filters have a working anti-drain back valve.

Hmm that’s interesting to know about the WIX, I specifically switched to WIX under the impression they’re some of the best filters out there. Pep boys has that Purolator in stock, I’m going to grab one tomorrow and throw it on. I’ll report back.

To note though since changing to the Valvoline VR1 20w50 and Wix Filter the engine is noticeably quieter and only clatters on start up but it doesn’t last nearly as long as it used to. It’s been hot here too 95 degrees the past few days and even with it being that hot and sitting in traffic the oil pressure doesn’t drop low enough to cause clattering like it did before.

I also did some reading and it does seem that in general these old 232s like to clatter especially on initial start ups. Ill be curious to see about changing filters if it helps anymore.

Living in a city with constant stop and go traffic it’s hard to get good solid readings on anything. I haven’t had much time to take it on a proper driver and watch the pressure.

I’m just trying to exhaust all my options before pulling the engine for replacement or rebuild. 

Keep in mind the more you increase wear, more parts will need replacement, and if you run the crank journals dry (hot weather, low speeds, thin oil film) scuffed crank will need more metal removed. As Igonr said in another thread, the choice is that you can fix it on your schedule, or the part's schedule...,

Well kept from here on out will get you more life out of it, but there's only one fix, past some point, probably well passed.

BTW Northern auto parts show a high volume pump if you want to play with yours.

I've taken two of these engines apart, one with only about 70k miles. There wasn't much for cylinder wear on that one but the other I had to use a ridge reamer to get the pistons out. I suspect you will have to do the same at overhaul if yours has 146k miles.

Although a silly mindset I feel if I were to pull the engine I’d rather upgrade than put the same engine back in. I’d love to ultimately put a V8 in the place of the 232. I’m honestly not sure what route I want to go which is why I’m trying to do everything I can to not dig into this current engine just yet. I do have a new oil pump and pickup to put on it. 

How difficult is it to pull the pan with the engine still in the car or is it just easier to pull the engine instead of trying to drop the subframe? I’ve pulled engines and have dropped subframes before so neither option is unfamiliar territory.

If I were just doing something in the bottom end I'd support the engine and drop the crossmember. The only catch is the wheels need to be on the ground or the upper arms blocked so the y don't come down. Last time I did something like that I ran the car up on ramps and left the wheels down, but still had jack stands under the front so only partial weight was on the wheels. Limits movement under the car some, but works if you're on a cement floor with a creeper.

A manual trans car could easily be converted to the 4.0 from a late 80s early 90s Jeep.

Use an adapter and run a 2bbl carb until you have time to sort out the fuel injection.

Just an idea..

I've been running 15W40 Diesel oil in my older engines, all the automotive oils are designed for

modern engines with roller valvetrain so the additives are not there for the harshness of the engine.

Once in a while Walmart has a special on a 3 gallon jug of diesel oil, comes out to like $10 per gallon.

Personally, I'd be thrilled with 45-50 psi at cruise. That's almost above normal for these old, understressed motors. Keep in mind it only takes about 3-5 psi to float the bearings, so you're still safe, even at idle/in gear. With regard to the psi drop with the car in gear at idle, this is to be expected, and also, might be a good idea to make sure that your in-gear idle speed is set to spec. If the idle speed is too low, pressure is going to drop right along with it.  IMHO, I think you are way overthinking/over-worrying about this. It takes a act of congress to kill these motors.

You know I have to agree with you. After researching the topic to death I’ve concluded that I believe the engine is more than okay. It may be tired or sludged up but I’m really not convinced it’s anything to justify replacing or tearing down and rebuilding right now.