Break-In Periods

[MIPS]

It was probably excessive but after 320000km and no signs it's been done before I sent my 258 in to have the block rebuilt after getting the head replaced and rebuilt in 2020. I do a lot of highway driving (like, 40km a day and around 1500km a month) and I didn't want a bit of early rod knock making my week miserable at any time in the future.

New camshaft, lifters, rings, pistons, bearings, oil pump, seals, hone and grind. While it's in the shop I replaced the ignition module and installed the upgraded coolant switch kit I documented a while back. Basically when it comes back the only original parts will probably be the block itself and probably the crank unless they run into any problems.
After that, the break-in period is my responsibility but the break-in period seems to be kinda vague and this isn't a performance engine, or a field Jeep so I'm not sure what I should and should not do for the next 5000km or so. I only have assumptions:

-Change the oil (10W30 non-synthetic) and filter every 1500km
-Adjust carb idle screws and feedback ratio; Retest Feedback system
-No hard acceleration
-No long distance cruising
-No heavy loading
-Verify timing and feedback every 2000km until broken-in

This might be correct or this might be excessive. I do not know. I've heard just about everything from using a different grade oil during the break-in, idling the engine for an hour above 1000rpm in the driveway and just driving it normally.

Edited: also since it's that time of the year I'm doing minor swaps as part of the complete annual tune-up, so new air filter, rotor, cap, cables, PCV, belt check and possibly a new O2 sensor as it's been roughly 60000km.

[Canoe]

It's different from what I was told to do.

At the time mine was rebuilt, it was explained that it was assembled using a modern "assembly oil". I was to drive it for a distance (I forget how long. 100 miles?), then do an oil & filter change.
(The engine didn't drive well during this. Poor acceleration, limited speed, difficulty with hills and poor mileage. Then I changed the oil & filter and it almost immediately drove like a charm. This was immediately at use driving from Nebraska to upstate New York, pulling a trailer, including cruising at 55 mph, 65 and even up to 80 in traffic somewhere in Ohio. See the next.)

I was also instructed to NOT do anything special driving wise for break-in. That the old-school break-in period was no longer required, except for the very initial running on "assembly oil". Note that this was with modern parts and cylinders specifically bored for them, same for bearings, throws, cam, etc..
(This surprised me, as I used to do aircraft motor break-in, with very specific RPM for x seconds, then another RPM for y seconds, then another for z seconds, etc., for a ten to thirty minute break-in, depending on the engine model. The second values ranged from 10, 30, 60, 120, etc., up & down.)
I was to drive it exactly how I would normally be driving it, with the oil I would usually be using (10W30 synthetic at that time). This was said to be for having everything seat in to match my normal driving. 

I certainly can't see your 1500 km changes doing any wrong. From everything I've read, continuing a short interval beyond the first one or two changes doesn't do much.

But for what you did, how do you define "broken in". It appears that you may break-in the engine for a type of driving that is different from what you eventually intend it for. Once you go to use it for "usual" driving, are you then subjecting the pistons, cylinders, etc., to the forces they'll actually "usually" be under, thereby subjecting them to a new break-in? I'd be wanting an oil & filter change shortly after that break-in. I'm also a fan of a few magnets on the exterior of the oil filter, similar to having a magnet inside the trans oil pan.

New cables seems excessive. But I can't see their condition. I'd check the rotor & cap condition first too, and not assume they're needed.

My two cents...

[MIPS]

So I should consult the shop as to their reassembly method as the traditional procedure may no longer apply and driving it home normally may be completely fine. That sounds OK.

But for what you did, how do you define "broken in".

Rings seated, any hard machining surfaces are lapped to seat their respective bearing and contact surfaces and any possible debris that remained either in the block after machining or on the new components establishing themselves in their new homes is flushed and captured in the filter. Abnormal performance, reduced economy and burning a little oil or in that period will be expected.
New values for cylinder compression may affect the currently set idle mixture ratio and confuse the computer, hence the carb adjustments but that's more routine service rather than part of the break-in.

Honestly I don't exactly know. This is the first time I've ever committed long-term to a car to say an engine rebuild is justified. I've always heard stories that older block designs had quirks, or that was just the unconfirmed sayings of a friend of a friend. I really should look at the TSM.

New cables seems excessive. But I can't see their condition. I'd check the rotor & cap condition first too, and not assume they're needed.

I was having weird miss issues right before I booked the shop time and shot the parts cannon at the ignition system because it's seven major pieces omitting the computer because it's an '82. The cables, cap and rotor were three years old so I might as well swap them regardless since they were cheap and in the process changed the coil as it had an oil leak and the connectors on the ignition module were falling apart so I swapped that out and now I got a spare. PCV is relative pennies too.
Beyond that, my usual tune-up is an oil change and filter, air cleaner, EGR cleaning, plug and timing check followed by an ET-501 diagnostic and a leak check.

[Canoe]

It's different from what I was told to do.

At the time mine was rebuilt, it was explained that it was assembled using a modern "assembly oil". I was to drive it for a distance (I forget how long. 100 miles?), then do an oil & filter change.
(The engine didn't drive well during this. Poor acceleration, limited speed, difficulty with hills and poor mileage. Then I changed the oil & filter and it almost immediately drove like a charm. ...

To be clear, there was:

• an assembly lube for assembling the parts into the engine block
  - I was told this was to make it easier to assemble, to ensure none of the parts got damaged during assembly, and to ensure that none of the parts were "dry"
• an assembly oil (break-in oil?) was added to the engine after assembly, same as adding the usual engine oil
• a long screwdriver was used to turn the oil pump manually to pump that oil through all of the oil paths
  (I have a conflict of memory on their using a cordless drill to turn that vs. by hand. Later, I know I did that by hand, then with a cordless drill on slow, after the engine sat for two years to ensure everything was oiled before first startup after the sit.)
• an engine oil & filter change, replacing the assembly/break-in oil with "the oil I would usually be using (10W30 synthetic at that time)"

[MIPS]

I quote the warranty papers I just received:

1- Before starting the engine for the first time, be sure it has been properly pre-lubricated. Break-in oil with a high zinc content must be used.
2- Do not add cold water while engine is running to the cooling loop. the engine must be at oeprating temperature
3- Sart engine and run at fast idle, approximately 1500rpm, and check the oil pressure, run the engine for 30 minutes even though coolant may reach operating temperature in a few minutes. Adjust, if required, carburetor and ignition time.
4- Start engine again and make a test run on the road at 30 mph in drive range. Periodically accelerate to 50mph and decelerate rapidly. Repeat this procedure at least 10 times.

Note: Applying loads to the engine for short period of time causes increased ring pressure against the cylinder walls and helps to seat the rings. This is especially important because you are breaking-in the engine with heavy duty oils. The rapid deceleration increases vacuum and gives extra lubrication to the piston and ring assemblies

-DO NOT BREAK IN YOUR MOTOR ON THE HIGHWAY!!!-

Drive normally but not at continuous high speeds or under heavy loads for the first 500km. Change oil and filter after 500km.

It goes on to include that a a local mechanic approved by the machine shop must perform a full test and inspection at 500km.