1000 miles

[Stuart]

I've heard different points of view on the first 1000 miles.  If around town is better, what changes happen to the motor if perhaps 800 of those first miles are on the highway?

 

Stuart

[FunElan]

In my experience, doing that may cause your piston rings to not seat properly

[adawil2002]

The proven method is to vary the rev range randomly over that time yet not above 4K. Varying the rev range will seat the piston rings. If the rev range isn't varied during the break in period and kept constant at say 3K for 1K miles the engine may develop a "flat" spot in the rev range.

 

If possible, take back roads instead of the highway. As the rings seat the engine should feel smoother. Remember to change your oil obsessively at 500, then travel 1000, then after going 2000, then every 4000 miles. While this seems like overkill, oil changes & filters are inexpensive compared to another rebuild. 

Edited May 14, 2020 by adawil2002

[Mike Self]

I broke in my complete engine rebuild on the way to Vintage in 2004--mostly on the interstate...varied the engine revs, shifting back and forth between 4th and 5th to maintain highway speed, and kept the revs, as Andrew said, below 4k.  Easy to do with a 5 speed.  That was 67k miles ago and the engine is running fine.  Oh, and soon as I returned (about 1k miles round trip) I changed the oil.  I used dino oil for that period, then switched to synthetic.

 

mike

 

 

[M3M3]

This is like a "which oil is better" thread. 

1000 mile break in is about 980 miles too long.  Rings set in the first few minutes of running... Done.

 

Last new engine build I had was run in on a dyno for 30min. Hard.  Then a couple of 20min track sessions below 6k rpm.  Done.  That engine got 25+ track/race days a year for 7 years and still set lap record after all that.

?

[rcf925]

I used Total Seal rings which are a little harder, They recommend 2000 mile break in until fully seated, Break in depends on the build

[TobyB]

Not really.  The 'soft' cast iron bore takes its shape pretty quickly.  I have used Total Seal rings 

a few times, too, and after the first 30 minutes, they're making all the compression they're ever going to make.

 

Nice static numbers, but I don't think there's much blowby difference between them

and a gapped ring under load in a running engine.  They ARE good for diagnosing bore damage, tho.

 

t

'the build'

[Son of Marty]

I'm with Toby I've had Total Seals seat in the driveway during the initial tune before hitting the street the key is to have your machinist follow their instructions on hone grit and pattern exactly.