25 replies to this topic

[klivins]

From my todays point of view It might have been a mix of all those things. I am still a novice here....

[jaydee]

The gunsons' tester is not very reliable in my experience. Anyway after 500 miles set mixture to a normal 2.5-3.5% CO at idle and start to work the needle for the cruising speeds and full power.

[Captain Mainwaring]

From my todays point of view It might have been a mix of all those things. I am still a novice here....

 

 

This is cropping up more and more - and yet I think people are more aware that it's OK to give an engine a bit of stick during running in. I think blaming mixture is rubbish - it's a mini not a F1 car, and nobody got glazed bores years back.

 

Leaves maybe oil....is it too good for running in?

[ACDodd]

I like people who ignore mixture ratios during run in, it keeps us engine builders in business doing re-ring work.........

 

 

AC

[Captain Mainwaring]

ACDodd, on 05 Jun 2013 - 05:51 AM, said:

I like people who ignore mixture ratios during run in, it keeps us engine builders in business doing re-ring work.........





AC

I was hoping for something a bit more "technical"

Just how out does it (mixture ) have to be before there are issues with the bores?

Sounds like you'd never be able to run an engine in during a good british winter, particularly a fuel injected one where you have no control over the choke.

Interested too, do you hand out a card with each rebuilt engine informing the customer of the limits for mixture, running in procedure and suggested oils?

Now, straight to the expert - does rich mixture cause glazing, or does it cause bore was leading to lubrication oil film failure and scuffing?
Reading the Jag forums, they have real problems with some of the 4 litre engines, particularly the nicasil bores, which if not warmed up before a shut down will get so much bore was that they lose compression and will be very difficult to start again - but this isn't glazing, and in anycase glazing will happen whether we want it or not, we just don't want it before the rings and bores have run in.

The OP said he pulled the plugs and had a good colour - yet still his bore were glazed, thus my question - was it really rich mixture that caused his bores to glaze?

Interesting posts about this subject here :- http://www.pistonhea...ic.asp?t=835560

Edited by Captain Mainwaring, 05 June 2013 - 01:48 AM.

[klivins]

regarding as what caused my bore wash - as I said in other topic, the lump was new old stock unit with crank, rods and pistons, hence the trueness of the bores, quality of the hone, etc is very unlikely to be wrong,

It is very much true that we - not knowing better - fiddled with the fueling way too much, doing everything possible the wrong way round. Upon first startup the ignition was wrong for the build, as long with too small carburettor.

Thus I believe the fueling (and may be too good oil, it was Valvoline Racing 20W50), and may be too aggressive running in caused the problem. As I was pointed out, with modern fuels the plugs must have been almost white grey shade, not light brown as mine were.

 

Now the honing is done by very reputable local specialist, and I am on my second try. First 200 miles driven, and, as I said, I am worried settings are too lean as of now. The engine does not smoke when idling, havent seen any traces of smoke also when driving. Plugs are brownish grey now.

[jaydee]

Brownish grey are too rich, anyway dont rely too much on plugs colour, minis are richer at idle and viceversa after few miles above 2500 rpm plugs will look like running lean.

Dont blame it on the oils, i would blame it on the quality of the honing. Valvoline is not too good to cause this kind of problems, is just an oil with low shear down and a lot of zddp.

Next time try comma sonic by the way.

And back in time they had bore wash aswell, but less than with todays fuel and they didnt care because 90% they neither knew that the engine had glazed bores.

Edited by jaydee, 05 June 2013 - 09:31 AM.

[ACDodd]

Each customer at ML Motorsport does not start and do the first drive of the new engine. This is the only way we can control the initial start and run of a new engine. ML does not sell engines to people who want to perform the first start themselves!

 

Bore problems show up as bear wear. Glazing happens and the surface of the bore it literally shaved off!!!. It is most noticed around the oil in pack ans is easly identified in the first few passes of the honing head when the bores are remachined. There will be visible worn areas around the oil ring at the top of the stroke. In more servere cases there will also be a lip present at the bottom of stroke. this can happen in a little at 100miles. Bore and ring damage can happen in as little as 20 revolutions. Usually if a new engine suffers with carb flooding during initial run the engine will suffer from damage to some degree.

 

The only time the choke should be use on a new engine is to start it. It must be returned as soon as the engine has fired. The engine must be allowed to warm a little before driving to make driving easier.

Bore glazing is also caused by insufficient pressure and a combination of bore finish issues as well as over fueling. The biggest issue with mini owners is overfuling.

 

There is absolutely no problem with running an engine lean during run in. As you should be abvoiding high load high speed running wher a lean mix can destroy an engine.  

 

I like it when people question these areas, however I have to deal with the reality of people running there own engines in an then being dissapointed that they don't make the claimed power. In 50% of the cases bore wash to some degree has happend and a re-ring & honme is required together with proper run in to sort the problem. It matters to me not whether you all run in your engines rich or lean, I am just passing on 20+years of enginee machining and building/tuning experience.

 

 

AC

[Gr4h4m]

Oh nuts being forced my car is never lean....

[Captain Mainwaring]

Each customer at ML Motorsport does not start and do the first drive of the new engine. This is the only way we can control the initial start and run of a new engine. ML does not sell engines to people who want to perform the first start themselves!

 

Bore problems show up as bear wear. Glazing happens and the surface of the bore it literally shaved off!!!. It is most noticed around the oil in pack ans is easly identified in the first few passes of the honing head when the bores are remachined. There will be visible worn areas around the oil ring at the top of the stroke. In more servere cases there will also be a lip present at the bottom of stroke. this can happen in a little at 100miles. Bore and ring damage can happen in as little as 20 revolutions. Usually if a new engine suffers with carb flooding during initial run the engine will suffer from damage to some degree.

 

The only time the choke should be use on a new engine is to start it. It must be returned as soon as the engine has fired. The engine must be allowed to warm a little before driving to make driving easier.

Bore glazing is also caused by insufficient pressure and a combination of bore finish issues as well as over fueling. The biggest issue with mini owners is overfuling.

 

There is absolutely no problem with running an engine lean during run in. As you should be abvoiding high load high speed running wher a lean mix can destroy an engine.  

 

I like it when people question these areas, however I have to deal with the reality of people running there own engines in an then being dissapointed that they don't make the claimed power. In 50% of the cases bore wash to some degree has happend and a re-ring & honme is required together with proper run in to sort the problem. It matters to me not whether you all run in your engines rich or lean, I am just passing on 20+years of enginee machining and building/tuning experience.

 

 

AC

Don't confuse "questioning these areas" with wanting to separate fact from fiction.

[klivins]

After 500 miles all looks OK to me. In need of richer needle now, have feeling after 4000 rpm the carb really leans out.