Running in a rebuilt engine

[Alacrity]

If you ask 10 people in 'the know' about how to run in your expensive rebuilt engine you will probably get 10 varying answers. Here at this website is one you probably wont get. However it makes a lot of sense to me, it common sense if you think about it that the rings need pressure on them to break in correctly. Food for thought.

I have an engine I will shortly need to run in . . .

[catweazle]

contreversial indeed,i remember new 2 strokes siezing up if you did that from new,especially the Ambasador which had an iron piston.that was 40 yrs ago.

[Healey75]

I was taught it takes about 10 hours to run in and bed in a recon engine, initially run it at a fast idle in neutral until you get bored and the set up feels right, then start gently keep to mid range revs but don't let it labour then slowly increase revs but don't drone along at the same revs all the time and vary the revs from time to time, go back to idle occasionally, build the revs up as time passes and towards the end of the 10 hours give the engine full throttle just for short bursts by then it should 'feel free and eager', then enjoy! but don't hold it flat out for long periods build up to it over 2 or 3 outings. All the time watch for overheating especially to start with as there's plenty of friction to generate heat. no warranty given or implied but it worked for me on the water and 4 wheels...

Oh, and on a car engine run it in on a cheap oil to help the bedding in, if you use a top quality oil it's too slippery and and the bedding in is slowed or even halted. change to a decent brand after running in. The way I see it you're try to wear then engine parts just a tiny tad during running in so they all snuggle up together and mate properly and generate the correct running clearances.

[Alacrity]

When I worked rebuilding Perkins diesels in the late '70's I used to dyno test most of the motors. We used to follow procedures laid down by Perkins that involved light loads at lower rpm's working up through heavier loads with more revs up to full throttle power tests after 5-6 hours (on a 6.354). However methods change as knowledge increases & whilst in some respects it goes against the grain what this website is saying, it makes total sense to me re. the rings bedding in - which after all is a major source of power in an engine, poor ring sealing = low compression = lower power. Agree about the oil though, don't use synthetic 2 stroke oil when running in.

[bigminiandy]

When I rebuilt the motor in my classic mini I was advised of a few different ways to run in and ultimatley went with the give it hell version. As a few racers said to me if it's gonna break it'll break within the first 20miles, it didn't and now runs very well for a 1 litre with a slight over bore. Made 53 horsepower at the wheels on the rolling road which is considered pretty good for a mildy modified 998cc mini.


Photo was taken just before I'd finished connecting the pipe work

[Alacrity]

I still can't work out how you get in a Mini!

[bigminiandy]

Practice. Seem to get some funny looks when climbing out of it. Every body expects some 5ft odd shorty.

Bucket seats help as done shoe horns and grease.

[welshhealey]

Someone once told me many moons ago, "you don't get into a Mini, ..you have to put it on !"