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Discussion Starter · #1 ·
We're supposed to get the 4.0 back from the machine shop on Friday, and assuming all goes well it should be running by Sunday. They did a 10/10 on the crankshaft and bored the cylinders .030". Mostly new innards except for the crankshaft and valves (new cam, lifters, pistons, timing set, kitchen sink)...

Haven't researched it yet, or even asked my friends who might know, but figured I'd put the question to this august group of experts as well... what is the recommended break-in procedure after an overhaul? I vaguely recall having read about using a certain oil and limiting revs and load for a certain number of miles, but that was information that I wasn't really looking for at the time, so just kinda skimmed over it.

My plan as of now is to use the factory recommended oil, drive it around town for a week, put maybe 100-200 miles on it, then do an oil change and assume it's good to go. What do you guys think?
 

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Does anyone ever brake-in a new car, no. Get in it and drive it like you would normally drive it. Doesn't hurt to change the oil @1k miles but it's not necessary either.
Enjoy
 

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I swapped in a new short block last August and the engine came with very definite break- in instructions, they recommended Shell Rotella Triple T oil and we had to run the engine up to about 1500 RPM for about 10 minutes while varying the RPM a bit then up to about 2200 RPM for 15 minutes also varying the RPM a bit. They did not want the RPM to be held steady.
 

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My long block came with similar instructions. I believe they mentioned running for a consistent 2k rpms for 20 minutes, then varying RPMs for 10 minutes after that. Then changing the oil.

I opted to use a thin 5-w20 oil for the break-in with Lucas break-in additive. Then I used the normal 10-w30 with the break-in additive for 500 miles after that. Then finally, went to a normal oil change routine.
They never mentioned limited engine load to a certain range during break in.
 

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Discussion Starter · #5 ·
Thanks for the responses. I'll ask the shop if they don't provide instructions... I get the impression they aren't accustomed to dealing with inexperienced mechanic-wannabe types like me...
 

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The machine shop should give you instructions for break-in, basically your seating the rings and breaking in the cam "lifters and cam mating together".

What your really doing is getting the engine up to temp running it at about 1500 to 1800 rpm for 10 to 15 min, then vary the rpm for another 10 to 15 min. shut it off and let it cool down change the oil and check fluids.

-Jason
 

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Discussion Starter · #7 ·
As I suspected, the shop didn't really give me any specific recommendation other than to get the rpms up for about 30 minutes (as has been outlined above) and use break-in oil. I went to the parts house, and they didn't have anything they sold as a prepared break-in fill. They recommended the Lucas additive, so I'm going to basically go with Razz and do the 5W20 first, then switch to 10W30. One question I had was whether the filter needs to be changed after the break-in. I assume not, but yes after 500 miles.
 

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I would use a higher - dollar filter and change it out after the 30 minute break in. My impressions are that the initial break-in is to also clean out any fine metal millings/crap they used to clean the block after machining it. So I personally would change the filter both times just to be safe :)
 

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They "should" tell you to fire it up and run it up to about 2k rpm for about 20 minutes. This is to break in the cam and lifters..nothing else. After 20 min, turn it off and let it cool. Check for leaks and top everything off as needed. Drive it for a 100 miles or so and a few drive cycles before you really stand on it then change the oil. After that get after it....
 

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Don't use conventional oil with an additive, its rather expensive but proper break in oil is what you want. It usually involves running the motor around 2k rpm for 20 min to harden your wear surfaces.
 
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