I just got my motor in my 93 Z totally rebuilt and was wondering what the "Break In Period" is. Some people say 500 miles and some say a thousand. Anyone else have some kind of clue?

 

id say 500 when everything is new, but its just ur engine so id say 1000 so everything is in tune before u really go slamming the peddle

 

I'd probably give it 1000.

 

Well first of all, 90% of the break in occurs in the first...er...30-40 minutes of run time.

For the best brake in, start it (for the first time) and keep adjusting the rpm for a few minutes.
Later start it again, and drive it. Take it up to a good 3500-4000rpm's under a decent amount of throttle (after it has warmed up, but warm up under driving conditions).
Let it cool, and later take it out for a third time, and give it a good bit of gas, and take it up to within 1000rpm of your redline (based on what internals you have used).

Change the oil and filter(assuming about 50-100 miles are on the car).
Then pretty much drive it normally.
You probably dont want to run it all the way to redline untill a few hundred miles are on it, but you dont want to baby it eather.

On average a stockish engine typically doesn't get to its true potential untill several thousand miles. Of regular use.

 

This is what I've been told to do by the mechanic. For the first 500 miles try to keep the RPM's under 3k but over 1500. Try not to exceed 55mph for long periods and try not to sit idling for long. I would also change oil after immediate start up running for like 20 minutes. Then change again at 500 miles.

I would figure 1000 miles is a good number, even though it wont be fully broken in until like 2K.

Good luck.

 

try not to do anything for very long make sure its changing... like on my new truck i just got F350, we wernt supposed to tow until 1000 miles but we were supposed to change the speed as often as we could

 

If it were me, I'd just do frequent oil changes at first, to flush out any assembly lube, etc, and I'd drive it like I normally would. Take it easy when the oil is cold, but once warmed up, go full throttle as often as you like. The only thing I'd do differently with a new motor is to avoid long distance trips where I drove at the same speed for a length of time. I'd make sure the first 1000 to 2000 miles were all city type driving with tons of varience in rpm and load.

 

Just like Patman said.....break it in the way your going to drive. If your going to baby the car then break it in that way. If your going to run it hard,,,might as well go knock off a few Mustangs

 

I have to agree with you Dolby 109. Had mine dyno tuned just as soon as it was built buy the company that built it. We just let it run at low idle speeds for 15 mins to let every thing seal good. Made a few mid to high revs, and then flogged the **** out of it. Made 19 pulls from 3,500 to 7,400. BREAK IT IN LIKE YOUR GOING TO RUN IT.