Running-in

[Adam43]

After a winter rebuild I'm running in 4.2l XK engine in an E-Type. I wondered what rules you lot used for running in. My plan was
500 miles with Penrite running in oil with 3,000rpm max.
Oil and filter change then put 1,000 miles on it limited to 3,500rpm max.

In the end it will be more 800miles with running in oil and 3,000rpm (A trip to the Cotswolds was poor timing). I have now decided to do 1,000miles more before another oil and filter change just before a trip to France.
The running has mostly been to rev limit, although I've not worried about a couple of hundred over. I have tried not to sit at the same revs for a long time and used assertive, but not flat out acceleration when suitable.

Oddly for an XK engine it isn't using any oil!

[Luxobarge]

I think your plan sounds just about spot on to me. In addition to limiting revs,m also don't "labour" the engine - better to drop a gear and increase revs than use a lot of power at low revs, but I'm sure you know this!

Cheers

[pryantcc]

Hi guys, please feel free to tell me to google it, but what's the science behind all these running-in miles?

Why is constant engine speed bad?
How is labouring a rebuilt/new engine after a thousand miles any more damaging than labouring an older one?

I'm all for being nice to engines in an effort to stop them breaking, but don't understand running-in beyond the first few hours. New rings scraping bores, new shell bearings bedding in??

Thanks,
Paul.