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vintaylor

Liner Nip Advice

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Hi Guys,

 

Had my lines replaced for correct 'B' spec liners from garry kemp (top chap who's very helpful! - Highly recommended!!)

 

So here's the short story:

 

I handed the block over to an engineer here in Malta who has been highly recommended by quite a few people.  He pulled the old liners and cleaned the seating and re-installed my new liners.

 

The doubts I am having are that I did not give him the old head gasket, so I cannot see how he has torqued down the liners to get the correct nip.

 

I've removed the block studs and I took the engine back over to have it measured.  These measurements where taken without any liner clamps being torqued down.  (might be good to note that the new liners have been installed over 6 months ago).

 

Here are the measurements:

 

liner 1 (found at water pump end) - 0.2mm

liner 2 - 0.15mm

liner 3 - 0.13mm

liner 4 - 0.3mm

 

So these are obviously not within the 0.125mm tolerance.  He has informed me that these measurements are fine since they are above the tolerance, meaning that once the head is torqued down they should fall within the tolerance.

 

What do you guys think?  Should I try and get a set of liner clamps and torque down to head settings and re-measure ?

 

Also I'm completely new to all this .. and not sure if I should put my trust in this guy and go ahead and rebuild the engine as is.

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Hi Vin,

I've just fitted my new liners in the block.

I can say, as for the manual, that the tolerance needs to be right without torquing down anything, once checked and the nip is correct you must apply the sealant and the head with a gasket. Once dryed up check again the tolerances just to be sure but I think the nips would be the same.

So, in my opinion I will not fit the liners with that measures....

I have the correct Lotus tool for the measurament if you need it I can put the tool in the package you are waiting.

ciao

Giorgio

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Hi Giorgio,

 

I had a feeling this would happen with my engine .. Looks like I'm going to have to pull the liners and re-install.  

 

It would be great if you could post out the tool for me to re-measure everything ... I was hoping to avoid re-building the engine myself, but looks like that's what I'm going to have to do!

 

Does anyone have any liner clamps I could borrow for a while? :)

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Hi Vin, those nip measurements are way too high, and I wouldn't give any credit to the mechanics view it'll be ok when the head is torqued down.

Liner sealant needs to cure with the head fully torqued down, and as long as the crank and pistons aren't turned with the head off you won't.need clamps.

However I've made a set out of nuts large washers and old gudgeon pins you'd be welcome to borrow.

BTW how was the nip measured?

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Hi Paul,

 

Thanks for the info as always! I'm going to take it to another engineer and demand that he pulls the liners and get everything to the ideal tolerance.

 

Would it be possible for you to lend me the liner clamp kit you've done so I can take it with me to this new engineer.

 

I really don't want to take any risks with this engine, so I'd rather have everything confirmed.

 

From what I could see he had a flat bar with a depth micrometer attached to it ... He placed the flat bar on top of the liner and calculated the distance from the liner to the block.

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All I'd say is that Lotus specify a minimum and MAXIMUM nip, take from that what you will.

Make sure the nip is measure once the liner shave been made to be fully seated home, so ideally they'll have been pulled in by tightening the head down (old gasket) first.

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Indeed, although in reality the difference between max and min is about the thickness of a human hair.

 

In other words, there is very little margin of error.

Especially, with widely reported issues of HG weeping.

 

Vin,

The other thing about the nip figures quoted is that they are so variable, when of course they should be within a thou of each other, so there's no way the head would pull, them all down to within spec.

Also, was the nip measured after you cleaned the top of your block? If not then the measurements would increase.

 

Either way, you're welcome to borrow my liner clamp kit. It's a bit Heath Robinson, but it works. Although, there is a school of thought  that suggests the liners wont budge once the Loctite 572 has cured. Still, better take all precautions, I reckon.

 

You're definitely doing the right thing by making sure the nip is correct. It'll save you all sorts of problems later.  

 

Have you kept the old HG for fitting the liners? Whatever you've done to the engine, and whether or not you've had the head skimmed, the thicker (than most variants of Coopers HG) Goetz HG should prevent piston/valve contact.

 

However, it's not possible to guarantee this without a trial clearance check with plasticine, which I would recommend in all circumstances unless all you're doing is replacing rings etc.

If you were somehow able to be absolutely sure that piston/valve clearance wouldn't change as a result of your rebuild, then you wouldn't need to torque the head down whilst the sealant cures. You'd just install liners/pistons etc and fit head once as part of the final build process.

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Hi Paul,

 

Measurements were taken after I cleaned the block surface.  I'm going to take it to someone else and get a second opinion..  And I'll make sure to give all measurements and proper sealants etc..

 

I believe my old head gasket is at my mechanic... Will pass by and pick it up

 

I bought the head gasket from Garry Kemp.  not sure which brand it is since I bought an entire upper gasket kit from him.  Can check at some point tomorrow.

 

Should I be OK if i re-install the liners with new sealant and torque down with just liner clamps rather then the entire head?

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Is it possible to buy a liner nip gauge? I have this job to do soon...

 

Paul.

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Paul,

yes it is, but I just bought a stainless steel engineers square, cut the thin angle off, and drilled two holes in the handle corresponding roughly with the liner and block locations as it spans the liners.

Then used a depth micrometer to measure - just subtract the thickness of the square from the reading on the depth gauge. 

The difference is liner height above the block i.e. nip.


Hi Vin, in answer to your question, the liner clamps will not exert enough torque on the liners.

If you saw them (mine and the Lotus types), you'd see why.

They also don't cover the whole liner, only the sides, and are really only for stopping the liners from moving if the engine (incl. crank and pistons) is turned over.

It's a retrograde step, but using the old style Hylomar to seal the liners is less dependant on the need to fit the head whilst it cures as it remains more flexible.

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Hi Paul,

 

I see.  I'll go ahead and pick up my old head gasket and check my new one to see the make.

 

I think it would still be wise to keep the liner clamps in throughout the course of the build.

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Hi Vin, assuming the old HG is a Coopers, it could be one of three different thicknesses.

The thickest compares with the latest Goetz, so it's worth checking and comparing as again it will affect piston to valve clearance.

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Okay, troops. Firstly, liner clamps...a complete waste of time. Have any of you actually pulled the liners from one of these engines? Using Loctite 572, you will need a really robust liner pulling tool to move them at all. They are NOT going to move on their own! I fabricated a tool consisting of a length of 12mm diameter threaded rod, nuts and washers and some shaped 2"x1" steel tubing, plus a couple of wooden blocks to space the upper part away from the block. This managed to heave the liners out, but in the process the steel tubing deformed markedly, so the idea of the liners moving by rotating the engine can be forgotten. What it might have done with the original sealant, I can't say.

 

As for measuring the liner nip...I've found that a robust steel straight edge and some good feeler gauges work as well as anything else. Feeler gauges ought to be used as go/no go devices...the smaller size should fit and the larger size shouldn't go under. Forget all this stuff about "sliding fits". A depth micrometer...as long as it calibrated...would be fine, or a digital vernier would be OK too. Is the head flat? They do tend to bow one way or the other. Once you have measured all the liners for variance...done by fitting them "dry" into one hole and measuring the nip for each liner in that same hole, then you can take one of the liners and fit it "dry" into all the other holes and measure them. At this point you will have calibrated all the liners and all the holes, and you can decide which liner you are going to fit in which hole. Do this "dry" and check all the liner nips. Needless to say, the lip that the liner fits on in the block has to be squeaky clean and the edge of the block clean, too...but don't try to overdo the block edge, or you risk removing metal and causing a spot prone to weeping. If your head bows one way or the other, you can adjust for this by selecting the liners to fit the head profile...this will give a very small adjustment, but it's worth considering when deciding what liner goes where.

 

When it comes to finally fitting the liners, getting the block warm and putting the liners in the freezer makes fitting them a lot easier, they will just slide in without any tendency to get out of line and jam in the holes. A good coating of sealant on the spigot of the liner and around the lip, then slide the right liner into the right hole in the right alignment. Once you have them all in place, fit the head with a gasket...the old one will do nicely...and torque it down. No need to go for the new angle procedure, simply torquing it to the figure on an ordinary torque wrench will do, all we're doing is making sure the liners are held firmly as far down as they will go, with the lips pushed together.  

 

Then go down the pub for a bit and leave it overnight. You can leave it like this, the sealant will harden anaerobically although the exposed sealant will stay soft....once the block is filled with coolant, then that,too, will be in an anaerobic state and harden off  as well. Once the head is removed again, recheck the liner nip...it ought to be in spec. after all that effort!!

 

Piston to valve clearance....unless you have modified the engine by skimming the head to increase the compression ratio or fitting high lift cams, this isn't going to be an issue. As has been said, a bit of plasticene can be used to reassure you if you wish.

 

I wouldn't ever try to assemble the engine without fitting the liners and the head and allowing the sealant to cure before doing the rest of the build; the new sealant sets anaerobically, so if the liners are disturbed in any way during fitting the pistons and crankshaft/ bearings etc. you might get them displaced and stuck in the wrong place. Liner clamps sound good, but fitting the head and allowing the sealant to cure is easier and better.

 

Finally, make sure the pistons and conrods go in the right places and the right way round, bags of oil in the bores, space the rings properly on assembly. Use the Graphogen grease on the mains and big ends, this provides lubrication for the first start and will dissolve in the oil as the engine runs ... and don't use synthetic until the beast has run in, or the rings won't bed to the bores. 

 

Fun, this stuff, isn't it?!!!

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John,

Very detailed and useful input!

 

A couple of observations -

I always understood that feeler gauges wouldn't give the right amount of accuracy. Especially if req'd nip is say 0.003 - 0.005?

Liners can of course be checked in any of the block seats, and rotated 180deg to acheive best nip.

I found the Loctite 572 sealant acted as lubricant, so didn't need to put liners in the freezer first. Twisting them as you insert also helps prevent binding.

I didn't use the new 'angle' torquing procedure either, but I did use Wellseal on both sides of the HG (as a bit of extra insurance against weeping), and torqued all nuts to 75lb.ft.

Deffo no synthetic during running in. This won't take 1k miles, just vary revs, slowly increasing after the rings have been bedded in. This is done by several brief applications of full throttle in 4th gear from about 40mph, for 10 seconds. allow engine to cool between times.

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another  couple of observations,

feeler gauges, I think, if you want to know if the tolerance is within specification are good, if you want to know how much is the tolerance no....

I have never heard of a Goetze gsket fitted with sealant on a lotus engine, the new Goetze gasket is also thicker than the old metallic ones and this is good for head machined job, reprofiled cams etc,,,also for compression in case of HC pistons.

I don't think is necessary to check piston/valve clearance with plasticene during a standard/routine engine rebuild, if you are building a semi race engine ( like me.. :fun: ) it's worth for sure.

Giorgio

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Giorgio, agree in normal circumstances a standard rebuild shouldn't affect p to v clearance, but in the course of most builds the head is skimmed at least to clean and you don't always know how much has been removed during the course of previous builds.

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I had to press my liners out with a 12 ton press and they went with a big BANG! As mentioned above they weren't going anywhere by themselves.

 

Paul.

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Home made Liner Nip Tool, flat aluminium bar (with a slot) and a  home made (lathe) brass "sliding" bush which clamps / holds the micrometer perpendicular to the flat aluminium bar.

 

post-721-0-52509100-1371291022.jpg

 

I checked the tool first on a flat piece of glass to make sure everything was straight and flat.

Take a measurement on the liner and another one on the engineblock and the difference between them is the nip. Repeat this 7 more times (4 liners / left- & rightside).

 

 

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