Crate Motor Break In???

Some of you may know that my 2000 XJ had a cracked head and it was cheaper for me to buy a mopar crate motor than to have the head replaced and the original motor gone through. The original motor had rod knock and was sucking 1 gallon of coolant every 200 miles. So I ordered a new crate motor from mopar and it came in today. The dealer is doing the install and it should be done by Monday. The crate motor came with an 0331 head on it wich is the same casting number as the head on the original motor. We all know that the 0331 head is prone to cracking in overheating conditions. The new crate motor head was magnufluxed at the factory so it is just fine. I heard that the 0331 head that came on the newer 03 and up engines is a stronger head and is not prone to cracking as the 00-02 heads were. I have a few questions that I will ask the dealer and any input from everyone here would be much apprieciated.

1. Is the 0331 head on my new crate motor something to worry about?
2. What is the break in procedure for my new crate motor.

I would get some of the GM E.O.S. break in lube and add it to the oil. Do a search about low zinc oil and cam failures. From what I have researched the EPA has required that lower amounts of zinc be added to oil.
I know that I have read enough about cam failures on "new" jeep motors that I would definitely use this stuff for break in.

You should have no worries about the head as long as you don't overheat the engine. There are various schools of thought about break in procedures. I suggest doing what the manufacturer says.

X2 on the EOS. Or if you have a hot rod shop near you, pick up some comp break in lube.

The first fire up and cam break in is the most important and scariest (basing this on my Chevy motor). Good thing the dealership is doing it. Usually break in is no long periods of idling, no hard acceleration. Vary your RPMs. Good luck!

Vary RPM's for the first 500 miles. Freeway trips not recommended. Then you can make sure the rings are breaking in by doing short runs with short high acceleraton/full coast cycles. A dozen or so of these should seat the rings. I've broken in motors before and babied them for too long. The rings never did seat and had high oil consumption after that. Once this is done, change the oil. If you haven't already, search for the oil discussions that talk about ZDDP.

Hopefully your later head is improved. Just monitor your coolant like you need to anyway. If you start to use some, check for the milkey oil fill cap. Nothing else you can do.

when i built my 306 for my mustang the ring instructions suggested 1000k miles or a night at the track to seat the rings. the choice is yours.

Seconding this. For my race motors, I break them in on the dyno or at the track with wide open throttle runs. Roller cam motors are broken in before the first warmup anyways.

The coast cycle after the acceleration draws the oil back up the cylinder walls.