Running in rebuilt M20b25 engine

[Avinit4]

Hello people
Anyone know of a thread or Guide for running in a rebuilt M2b25 engine including when should give first oil change, check valve gaps etc?
Engine had new crankshaft - piston rings -
Ive tried looking threw guides and search but couldn't find anything hence this question.. Cheers

[e30mreg318i]

keep it below 4000 rpm for 1000 miles, then oil change, valves should n't need checking but if you have the time, why not?

[daimlerman]

When I built my 2.7 M20;
First 250 miles at 1500rpm,odd bursts to 2000rpm.
Next 500 miles at 2000rpm,odd bursts to 2500rpm.
Next 500 miles at 2500rpm,odd bursts to 3000rpm.

And so on until I was using full engine speed.
I also changed oil and filter at 500 miles,and again at 2000 miles.

Engine has now run about 65k miles and does not use oil.

[maggspower]

Break it in hard. Use the cheapest mineral oil you can find or proper running in oil. NO SYNTHETIC.

If you have a new cam, hold it at 2000rpm for a few minutes to bed the cam, this will give you chance to check for leaks etc.

Then get it out there, drive the engine at full throttle up to about 4000rpm in a high gear followed by no throttle over-run. This forces the rings into the bore wall bedding them in, the over-run sucks oil up the bores to wash the bedding in particals away. Do not let the engine labour, or keep it sat at cruising speed, this will glaze the bores. Constant movement of the throttle.

Do this for about 10 miles, go back and change the oil and filter while still warm. The next 300 miles take it easy, but keep stretching the engine.

Another oil and filter, then you are good to go. This is the way I do it, others will no doubt say different.

The first start and 10 miles is the most important.

[bss325i]

This^^^^^^!

[lhd220turbo]

You can do it in less than a 100 miles

A very common mis-conception is that you have to run engines in for 1000+ miles, in reality its all about getting the rings to seal against the bores.

i've assumed its been built properly and had a rebore/hone? if so the bores will be slightly rough to help the ring bed in

If you treat the engine like miss daisy by keeping the revs low and not "give it some" all you'll do is glaze the bores and have poor sealing between rings & bores, resulting in a expensive oil burner

the way i would do it

warm motor up to temp
20 miles at 1/3 throttle, but make sure theres plenty of accelrating/decelrating
20 miles at 1/2 throttle, same as above
20 miles 3/4 throttle, same as above
20 miles at full throttle, same as above
change oil for something decent, job jobbed

alot of high HP engines are run in on a dyno for a few minutes then given death

[lhd220turbo]

beaten to it by maggspower!

[Avinit4]

Ok people...Thanks

[Jesus325iTouring]

When I built my 2.7 M20;
First 250 miles at 1500rpm,odd bursts to 2000rpm.
Next 500 miles at 2000rpm,odd bursts to 2500rpm.
Next 500 miles at 2500rpm,odd bursts to 3000rpm.

And so on until I was using full engine speed.
I also changed oil and filter at 500 miles,and again at 2000 miles.

Engine has now run about 65k miles and does not use oil.

Funny engine you got Malc, what does it use instead of oil?