I'm finishing up a (slow and drawn-out) rebuild on my 89 IROC's 350 TPI V8.

I'm not going to ask "how do I break it in" (yet), as I'm sure that's been covered many times before, and I've got a pretty thorough book on engine rebuilds that goes through that. Basically, the rule-of-thumb that I've been hearing is "don't drive it hard for the first 500 miles, because it's still breaking-in".

What I'm wondering, though, is if it would be okay to break the engine in on a trip. I'm thinking going out of town in a little while (about ~250 miles out), and thought the trip might be a good break-in for the engine. It'd be about four-hours away, on the highway at about 60 to 70 MPH, and on 2.77 gears, that's something like 2250 constant RPM on the engine.

I'm just wondering if several hours of uninterrupted driving is okay to break in a rebuilt engine, or if that's a Bad Idea (tm)... (never broken-in an engine before so I don't know)

Thanks

 

from what i hear.....and i could be totally wrong (it has happened) but it wouldnt be a bad idea just keep in mind that its a fresh motor and things can go wrong.....so do you really want to be 145 miles out and have something fail........just a thought but if you take a tool box and have a good knowledge of it the go for it.....bring some oil too (new engines like to eat a lil...)

 

I don't see anything wrong with a long trip to break the engine in. But like said, there could be things that go wrong with the new engine that might make unreliable.
It's true to to run the car hard for the first 500 miles or so. I wouldn't drive it like an old lady, but no WOT/Stop light racing for a little while.

 

i figure the first 30 minutes is really the brake in period. i do it in the garage keep engine speed above 1000 and under 2000 rpm. vary the speed and let it heat and cool several times. drain the oil and change the filter and refill with 30w then use it for round town and short highway trips. i wouldn't want to take a new rebuild on a long trip from home.

 

A long trip isn't really the best thing to do right at first... the engine should be operated through a variety of conditions for the first couple of hundred miles. It should not see any kind of steady-state operation at all. I like to not do pure 1320 blasts right at first; but not baby it either; for the first 5 or 10 miles of driving, I'll hammer it in 2nd gear or whatever between about 2500 RPM and 4500 RPM, and then let the engine brake the car speed back down to 2500 RPM, then run it wide open back to 4500, repeatedly. This uses cyl vacuum in between runs to suck oil all up around the rings, then the next blast seats them some more.

Put 2 or 3 hundred miles on your new motor first, then it's OK to cruise it. That will also give you a chance to shake it down for leaks, loose hardware, tuning, etc.

 

That was pretty much the same fear that I had--running into problems on the road and being stranded miles from nowhere. I think that will be enough to talk me out of it!

I guess that brings me to two more questions though...

1. I'm agreed (because I've never heard anyone disagree) that you do not drive the engine hard for the first ~500 miles. However, I guess I need to make sure what a reasonable definition of "driving hard" is. Like for me, when I'm driving in the city and taking off from a stop light, I rarely bring the engine above 3000 RPM. Unless I'm really trying to accelerate to get onto the freeway (where I might pull it to ~3500 RPM), the engine seldom sees RPMs higher than that. But, I don't (and don't plan to) race my vehicle, so to me ever bringing the engine to ~4500+ RPM is definately driving hard. (Mabye I do drive like an old lady!) Anyway, could anyone mabye suggest a good "rule-of-thumb" RPM that would be good to not go above during the break-in period?

2. With regards to the oil... I do like the idea of changing out the oil after the "initial" break in period. But, I've never really understood the reason for different types/why anyone would want a certain type over another. All I've ever used is Quaker State 10w30 (and I don't even know what thta means). What, ideally, do I need to be using during the break in period, and what would be the "best" to use thereafter? (and like, "30w"--is that shorthand for "10w30" or is that a different thing altogether?)

Ultimately, what I'm going for with this rebuild is for something that will be reliable and can be my daily-driver for at least a few years (through college and hopefully beyond). I'm prepared to baby this thing to make it happen, I just need to know what the pros do.

Thanks again

 

I was always taught that you shouldnt run an engine at a constant rpm for very long for the first 500 miles.

 

lot of people will say break it in with what you run, i use straight 30w, but don't run it and no it's not short hand for 10w-30. synthetic isn't a good oil to break in new engines with. i've built engines for other people and they've used 10w-30 or whatever they run with no problems.