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Paul Coleman

Setting 'nip' height when fitting liners

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I'm confused... how do you set the 'nip' height of the liners? In the manual it says to fit the liner, check the 'nip' and when the 'nip' is correct refit the liner and apply Hylomar to the linear face. My questions are...

1) How do you adjust the 'nip' if it's not correct?

2) Which face is the 'linear' face?

3) I see you need a special tool to extract them but how do you then re-fit them?

I want to take my liners out whilst the engine is apart and re-seal them.

Thanks, Paul.

Edited by Paul Coleman

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Paul,

There actually is no simple way of setting the "nip", it is what it is and if it was correct to begin with then you should be fine when you re-insert them. If they need to be adjusted it would have to be done by machining the liner itself.

As far as refitting, the liners are a tight slip fit and can be fitted by hand. Depending on what you use, you could also reverse your pulling tool to pull them back into the block but you have to be careful to make sure they are perfectly straight as you seat them or "galling" may occur.

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Paul,

I went through this procedure on my rebuild. Reason was because PO had a head gasket replaced at some time and whoever did the work removed the old material on the block with a scotch brite disc that ate into the metal. Plus I also wanted to make sure the deck of the block was square with the crankshaft.

After milling the deck the liner were put in and with the block still in the mill I used a dial indicator to check the nip. You could also use a ground steel bar placed over the liners and then insert feeler gauges to check it. Mine were high of course and so I brought them down by sanding them on a surface plate. Not a hard job but it takes time and patience. Don't bypass this step otherwise you are going to most likely encounter leakage issues.

If the surface area on your deck looks good I would say you are most likely in good shape. Before pulling the liners get you ground flat bar and check with feeler gauges to be sure. To pull the liners you might do a search for tools made for this or make your own.

Take your time and good luck,

Jeff

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"Linear face" is a typo...should read "liner face"! I wouldn't use Hylomar for this job, far better substances now exist...phone up S&J's and they'll send you some; it works a treat. You should apply this to the face of the shoulder on the liner which sits on the block...and all around the spigot of the liner where it goes into the block. It's a good wheeze to keep the liners in the freezer and the block warm, then one slides easily into the other. "Nip" should be measured "dry"..without any sealant...and you must ensure that the mating faces ar scrupulously clean, with none of the old sealant left..otherwise things will not seat properly. Ensure that the flats on the liners face each other, too. You can check the nip using a dial gauge, or a straight edge and feeler gauges. I measured each liner nip one after the other fitted into the same hole in the block...that way I calibrated each liner in turn, so I knew which one was slightly high or low etc. Then I took one of the liners and tried it in each of the four holes in turn, measuring the nip each time. Then I was able to even out the nip by fitting the individual liners to the holes. "Dry" fitting is easier if you squirt some WD40 or light oil on to the liner spigots before fitting them to the block..ensure all traces of oil are removed before final assembly; use cellulose thinners or similar.

You can make a liner removal tool ... I used 2"x1" steel tube across the block and liner and threaded rod and nuts to apply the force needed...spacing the top tube away from the upper surface of the block with pieces of wood to allow the liner to come out. Worked a treat!

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Paul, I assume it's iron liners you have (normal for an S1, S2 or early S3), so as per Jeff's suggestion, or another member here consulted the guy who builds engines for Mike Taylor, his method is to use an oil stone in situ but you still have to get rid of the grit afterwards).

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Okay, so if I've understood this correctly the liners are machined in the factory to give the required 'nip' which according to the manual is between 0.003"-0.005"

If I now measure them and they are too low there's nothing that can be done about them? I've put a straight edge (12" steel rule is all I've got) across the liners and then tried to measure the gap between that and the top of the block. I've only got metric feeler gauges and the thinest one is 0.05mm which equates to 0.002" but I can't get this under the straight edge so I'm guessing the liners are too low? This is strange because to the best of my knowledge they've never been out.

Andy - yes they are steel liners by the look of 'em.

Paul.

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Not exactly - The liners are a precision made item, as is the block. They are not machined for a specific engine. I have had 12 different liners in my block and have always managed to get within tolerance following the same process as John. Its not just a matter of 'nip' above the deck, each liner needs to be within .001 of its neighbour. I personally don't think feeler gauges are upto the job (I always use a dial gauge). You will also now be using a composite gasket - not the original coopers one. The good news is that it is more tolerant than the original version. I also think nip of between .001 - .005 is within tolerance for iron liners - so again, your less than .002 may be perfectly OK.

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Yes I'm sure you're right about the feeler gauges but that's all I have. The more I look at this the more inclined I am to give it to somebody to fix it and just wake me up when it's over.

Cheers, Paul.

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Paul,

Easy to over think it for sure. Make sure you have a good strait edge, preferably not a steel ruler. Get the proper imperial feeler gauge and give it a go. I would have to agree with what Steve said about being over .001 will be fine. If you are under your options would be to find different liners to try or deck the block.

You will be fine.

Best,

Jeff

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The head gasket went on an '85 S3 I used to own and I put it into Paul Matty's to fix.

Once they got the head off they could see the reason for the blown gasket was the liners had sunk into the block, so there wasn't enough nip.

They lowered the surface of the block using a scraper so restoring the nip back to spec before refitting the head.

I owned the car for a few more years & it ran perfectly until I sold it.

If the liner is too tall you have to shorten it & if it's not tall enough you have to shorten the block.

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Once you've got your straight edge across the liner...can you see daylight between it and the block? If so, you do at least have SOME nip....I agree about the difficulty of using feeler gauges, but one isn't trying for an accurate measurement, just a "go-no go" determination. So, even if the thinnest of your metric gauges won't go through, but you can see daylight, you are probably still OK. You can also check the relative heights of the liners this way, by running your straight edge along all four and having a squint!

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I put a steel rule across the liners and I can see light between the block and the rule on all the liners. I reckon the relative heights are pretty damn good and I'm sure they've not been out the block since it left the factory.

Paul.

Edited by Paul Coleman

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