33 replies to this topic

[PoolGuy]

I suppose I have trouble combining the 2500rpm for 20 mins stationary method with this. As someone else asked, how do you load the engine while it's doing 2500rpm?

 

 the rings bed in within 40-50 miles of use, so it critical you get some load behind them.

 

[Chris1275gt]

Just had An amusing thought, just imagining the 5.3 million mini A series engines sitting in the long bridge engine shop sat on test rigs for 20 minutes knocking the cams in. Build it bung it in the car, transport it to the dealerships, tell the customer to follow the running in procedure, change the oil at 1000 miles job done, a Ferrari or Porsche it ain't and that was with the tolerances they were made to before the computer came along.

[PoolGuy]

And there’s another variable, the wilder the cam, the more care you have to take. When I built my first modified A series I knew nothing about running in cams (yeah yeah nothing changes), I built the engine with regular oil, no fancy building lubes etc. Started it up and drove it for 60 miles with a big grin on my face. It never missed a beat for the next 20k miles. From memory it had a Piper 270.

[Ado1379]

This is what was confusing me. So do I hold the car stationary at 2500 rpm for 20 minutes or so and then start loading the engine? Or just drive around for 20 minutes trying my best to reach 2500rpm. I would’ve thought that stationary at that rpm would be enough for the piston to bed in?

[Midas Mk1]

Just had An amusing thought, just imagining the 5.3 million mini A series engines sitting in the long bridge engine shop sat on test rigs for 20 minutes knocking the cams in. Build it bung it in the car, transport it to the dealerships, tell the customer to follow the running in procedure, change the oil at 1000 miles job done, a Ferrari or Porsche it ain't and that was with the tolerances they were made to before the computer came along.

 

Watch the videos from back in the day of the production lines, you'll see the engines ran in, i'll try find the clip.

[burchy35]

As they say hold it stationary for 20mins to bed the cam in. Then drive it, accelerate up to 4k then off the throttle to let the engine slow you down which helps bed the rings in. I do that for a good 30 mins then get it set up on the rollers to get everything set up especially the fueling or you could cause problems. That what I do with my track turbo, it's all too tempting to turn it up before it's set up right. Its important to change the oil after the initial bedding in.
It works for me and I have had no mechanical failures at 207ibs torque.
But it's all about the build and clearances, too tight and it will take longer to bed in and free up.
Listen to the people who have experience. I am not a clever engine builder like some on this forum.
The A series is a strong reliable motor when built right.

[Spider]

When I did work at Ford (a loooong time ago !) the engines they were fitting in the cars they were assembling at that plant were CKD from Japan (there were sold here as a Ford Lazer and were a re-badged Mazda 323), they would running them for around 1 minute on a rolling road at one of the very end stations on the line, then they would take the car out to their test track and do 1 lap. Every car off the line went through this. 

 

Back in the days they were doing the Escorts, the 'Sports' models that were fitted with side draft Webers were subject to two laps as they had issues from hot flooding.

 

In our local BMC Factory, every engine as it was completed and before fitting was ran for an hour on the engine dyno until fuel costs went up and this was reduced to 20 minutes.

 

I note that in all new cars, the owners manual always provides some advice as to correct running in procedures. Some seem to suggest as little as 300 miles and others, like say our Holden SSV Commodores had a 3000 mile Run In. I think to, the Ford Mustangs are similar.

 

Mhale, say it takes 3000 miles for rings to fully run in and I'd agree with that, however, they only need to follow a procedure for the first 300 - 800 miles.

 

 

I stress as I said earlier - this is not always a 'one size fits all.

 

I think maybe a step back here might be in order and look at what is actually going on during this break in / running in period to understand what's happening and it might shed some light as to why this is done.

 

Considering here first the Rings and the Bore. As many things that have been written and mentioned, these have high and low spots on their mating faces on both the rings and the bores, but, also, the Bore has (or should have !!) a Honed finish.   

 

Depending on the shop and how they may do the honing will also have a lot to do with running in and how long it takes.

 

I did a write up on this a few years back    http://www.theminifo...gine-machining/

Some shops bore and leave 0,001" for honing as they can get the job out quicker, but,,, I can't see how that will remove all the 'marks' from boring. I leave 0.003" so I can clean the bores up,, then hone them with a grit to suit the rings, finally, I plateau hone the bores with is a very fine hone and this 'knocks the tops off' the finish honing. This can allow for a quicker running in, but, from what I've seen, few shops will do this as it's another step and more time for them.

 

In running in, we are 'mating' the rings to the bores.

 

Keep in mind here too that the rings are lubricated by the Oil that's left in the honing and should be no more and no less.

 

How does the Oil get on the bores ?  There's no direct oiling of the bores (of course!) and so the only oil they'll get is what's flung up off the Big Ends as the engine spins. If it spins slow, there's little oil being pumped and little being flung off the big ends. Not a lot of oil is needed here as much should be wiped by the Oil Control Rings and these should leave a metered amount of oil in the honing for the rings. Cold Oil doesn't lubricate nearly as well as hot oil and is also a lot thicker and 'harder' to wipe away. Also, metals, like steel and cast iron will absorb oil, but when fresh machined or ground (in particular) are 'reluctant' to absorb anything, until they are heated and while that's occurring, to avoid scuffing, they need to be well drenched with hot oil.

 

In running, the engine bores flex, the rods (especially our off-set types) 'bend', the Pistons flex and the Rings are subject to a huge range of temps and pressures from extreme Negative to high Positive pressures. These all change with Revs and Load, yet we expect - demand !! - that they seal 100% under all these conditions and also keep Oil consumption low to very low.

 

We've all done some sanding at one time or another. If we sand back body filler, it's easy to make fast progress and likewise, if we sand steel, progress is slow. Why ? Largely because the body filler is soft and the steel is hard.  Also, there's a fair bit of heat made by this abrasive process. If we use more pressure, the rate at which material is removed is also faster and there's more heat made.

 

Some engine builders will fit fit a softer ring so they bed in fast. Great if you need to get on the race track in the morning, but, as mentioned above, being softer, it will wear faster. Likewise, usually temps at the ring faces are higher.

 

There's more to it than just this simple analogy, but one might be able to see why a fast break in also leads to a fast wear out.

 

I was showed a set of rings that came from a fresh built engine that came with the advice 'drive it like you stole it' to break it in. It smoked in short time and the rings were so soft, you could tie knots in them, Zero tension in them !

 

I've also hinted here in what's happening with breaking in Cams and Followers. These are steel and should have a ground finish. Fresh Ground steels don't absorb oil too well. The Camshaft Lobes are only lubricated also from the Big Ends. I have seen and fitted Cams that have a through drilling for Oil to be fed directly in to the Lobes, however, have a long think about what action is occurring here and you'll soon work out that while this does help, it's not doing a lot at all and it won't save the Cam Lobes and followers if there is a lubrication issue.

 

Breaking in of Cams and Followers is fairly universal. The advice is usually to not let the engine run under 2000 or 2500 RPM for 20 to 30 minutes. This is only to ensure there's enough oil being drenched on to the cam lobes and followers until these fresh ground parts warm up enough, along with the oil, for these surfaces to start to absorb the oil and take some in.

 

This is ONLY a very very simple summery of all this and hopefully it will shed some light.

[Steve220]

How do mainstream manufacturers do this?run every engine on a dyno for 20 minutes to bed the rings and cam in?Just interested,Steve..

As modern cars have better follower/tappet technology (usually oil filled), you don't need to bed them in. Not sure on what other manufacturers do, however I've seen some that put a car on a set of rollers during the production line and send it for 5 minutes under high load. Then drop the oil and fill with regular.

Edited by Steve220, 23 May 2020 - 06:56 AM.

[Steve220]

I suppose I have trouble combining the 2500rpm for 20 mins stationary method with this. As someone else asked, how do you load the engine while it's doing 2500rpm?

the rings bed in within 40-50 miles of use, so it critical you get some load behind them.

You've got 2 options, over think it and worry you'll never bed your engine in properly, or do what thousands of A series builds have done over the last 60 years with great success. I'm merely giving you the latter.

[Steve220]

You could do it in the garage but how do you load the motor?

I agree, 20 minutes at 2500rpm stationary sounds like madness to me. But as someone pointed out very early in the thread, you’re going to get a multitude of answers from people who think that their way is the best.

You're right, which is why I spent months researching and speaking to most A series engine builders in the UK as well as reading research articles and papers about this very topic. I took the similarities and presented them on here. If you want to do something else, that's fine by me.

If you fail to see the logic behind knocking in a cam, I suggest you look into/google bedding in a flat tappet cam, it's explained nicely in a lot of articles ??

[PoolGuy]

Not ‘failing to see the logic’, more a case of playing devils advocate to see if people are actually thinking about it rather than regurgitating pub speak.

Moke’s post has some very valuable info in it. Also as I alluded to earlier, you need to base your running in process on the spec of your engine.

[surfblue]

How many of those 5 million plus A series engines fitted to Minis and millions more fitted to other BMC cars were religously run in?, or were they just driven normally by people who didnt know better or care? Dont lose too much sleep over it, dont let it labour too much and give it regular oil changes and all will be good.

[Spider]

How many of those 5 million plus A series engines fitted to Minis and millions more fitted to other BMC cars were religously run in?, or were they just driven normally by people who didnt know better or care? Dont lose too much sleep over it, dont let it labour too much and give it regular oil changes and all will be good.

 

I'd say the broader difference with the new engines that were fitted to the cars in the factory and one that's been reconditioned is the initial start and initial run. This is where usually the most 'damage' can be done and those from the factory were all already done in this regards, were as the fresh reconditioned engine hasn't

[MIGLIACARS]

Green and white minis use to never run them in

build

start

run so they idled and a basic setup then off to the rollers for a proper tune at full revs. well this was on there race engines, not sure what they did on a road car.

they said the race engines never lasted long enough to worry about running in. which in my case was true.

 

 

again myself on my race engines I build. there built installed started and sent to the dyno for tuning, im now fuel injected so let them do what they need to do, its basically flat out from word go once the perimeters are set correctly.

on the dyno i run them in on a cheaper oil say halfords which isnt crap stuff.  once dynod drain the oil remove filter and fill with the good stuff with a new filter.

 

Just my way on a race engine. Its lasted 3 years now with oil changed on every event.

others will have a different way im sure.   Bare in mind if you get 3000 miles from a race engine your doing VERY well.

[Dusky]

As Moke rightly points out, if you've put a new cam (and therefore followers) into an engine, you'll need to knock that in first.

Knocking in a cam
Use the cheapest 20w50 oil you can find as its not going to stay in there long. DO NOT let the car idle. As soon as it starts, get it to 2500 rpm and leave it there for 20 minutes. Make sure there are no leaks. If you spot anything serious, shut the engine off and stop the clock. Once complete, I do an oil and filter change as it will have been the first time the car has ran, so will clean out the engine prior to run in.

Running in
You can allow the car to idle, but only for short periods. The key here is to not give what runs, use 60-75% throttle runs to 4-4.5k rpm and let it engine brake all the way back to cruise around 2k rpm; engine braking is just as important to the run in process as throttle load. Let the engine cool for 10 seconds then do it again. If you're going up hill, use 3rd if you have to, but i did most of my running in for both versions of my engine in 4th. Put around 100 miles on, and the majority of your run in will be complete.

Remember when running in an engine, the primary reason is for the piston rings to bed. Every good engine builder i have spoken to says the rings bed in within 40-50 miles of use, so it critical you get some load behind them.

The cheapest? No. The most expensive running in oil you can find. I've seen enough cams die in the first minute because their cheap oil didnt protect it.