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So…I’m making some progress on this debacle. I decided to pull the 360 out of one of my CJ’s for a donor. I rebuilt this motor some years back, .030 over. It has maybe 35k miles on it.

It has a Holley Projection TBI kit on it. I’m going to switch to the Duraspark ignition that this motor has on it.

This motor has been sitting for a few years so I’m not going to make the same mistake twice. Since these pics I pulled the pan and valve covers and plugs. I squirted some Marvel Mystery oil in all cylinders and let it sit a bit. Rotated the motor by hand and everything seems to be moving properly. Oil pick up was clean etc. I’m going to replace the RMS and water pump for good measure…and seal it back up. I’ll pull the distributor and spin the oil pump with a drill to prelube and make sure it’s oiling right before I put the covers on. Slow and steady progress.

I am going to pull the head on the old motor after removing it to see what went wrong. I’ll post some pics when I get there.

Ok question here. I was replying to another thread about a harmonic balancer and it made me think about my situation. AMC v8s are externally balanced right…so this motor going in was attached to a T-18a. I pulled that flywheel off. It was originally mated to a TH-400. I might still have that original flex plate. Not sure. But…if I don’t have that flex plate…would I need to have a new flex plate balanced to the motor and HB?

I was originally thinking I would use the flex plate off of the motor I am going pull out of the Chief. But that might not match up balance wise right? Or am I over thinking?

Or are the flex plates all the same and it’s just the HB that is weighted?

What are you asking?

Some engines (like the 360) are externally balanced aka Detroit balance. These use the flywheel/flexplate and/or the front pulley "harmonic balancer" as part of the balance of the rotating assembly (crank, rods, pistons). Note this balance includes mechanical damping of the resonances of the crankshaft, not just static balance.

Some engines (like the 258) have internal balance aka neutral balance. These engines are balanced without adding the external flywheel/flexplate and/or front pulley.

Yes, both the flywheel/flexplate and harmonic balancer of a 360 are weighted, contribute to balance and are specific to an AMC 360. If there is a difference between the motor used with the T-18 and used with the TH400, it might be in the machining of the crank pocket for a pilot bushing. I don't think that's an issue for the 360.

An automatic requires a flexplate. A manual requires a flywheel. If either are meant to be used with a 360, they are specific to a 360. There is also a harmonic balancer specific to the 360.

So I’m still methodically but slowly moving through this project. Question…I have the oil pan and valve covers off. Everything looks good and turns smoothly. The motor has about 40k on it since a .030 rebuild back around 1998. I’m going to replace the rear main seal so I’ll have to pull the rear bearing cap. Should I re-torque all of the caps and the rockers since I have it open or is that a bad idea? I have no reason to believe anything is off torque wise. My feeling is I shouldn’t tamper with it but it’s on an engine stand and easy to do. Thoughts?

I removed the fuel injection system and ignition harnesses from the CJ. I’m switching to the Motorcraft Duraspark ignition from the ‘79 360.

I have done a few RMS, and never touched the other caps.

and now for the tricky part, there is a long post on theamcforum dot com about where to get the RMS... and the manufacturer or brand seems to be a serious fact to observe.

in the post rear main seal beware, started by SC397 aka Rick,

https://theamcforum.com/forum/rear-main ... 06551.html

the short version:

For those that are ordering single SCE seals....

I found it rather interesting that from Summit at least, you can get
the whole front end gasket set that includes the rear main seal for
cheaper than just the rear main seal alone!!

and amazoo has them too

Back to our program. I have used the felpro, but the last RMS I did was about 10 or 12 years ago

i'd say somewhere along the lines someone dropped something down the intake and that cylinder sucked it in there is too much small pinging on the piston for a valve problem IMO , with that 1 piston looking like that and i assume its the only one looking like that but i'd borescope the other jugs to look for similar damage but i would be worried about the piston dome failing and doing more damage to the engine , but i would look at a tear down and rebuild as food for thought, nothing i'd want to do that but based on that piston pick it may be the best course of action

Oh…I’ve abandoned that motor. It’s coming out. I’ll pull the head after to just see what happened.

I pulled a motor out of another Jeep that’s going in the Chief.

I scoped all of the other cylinders…they looked normal. I’ll post pics of what I find after. But that motor is getting moth balled. Damn shame…only 40k original miles. Let it sit too long. I should have pre-oiled it etc before starting.