Cylinder Liners

[JJC]

I had trouble with the engine on the 4. Water in the oil. The FO8 gaskets had failed, in fact corroded away. I have noticed that the bottom surface of the (new 2000 miles ago) liners is not ground perfectly flat. Didn’t notice this when I bought them not long ago. Do you think that was the cause of my troubles, or was it that I didn’t use enough Wellseal? JJC

[Motorsport Mickey]

How are they not ground flat ? across the width of the seat or around the circumference of the liner ?

How long did it take you to do the 2000 miles ?  with some owners 3 months, other owners 10 years. I wouldn't expect any corrosion within a couple of years to occur on the Fo8 gaskets even if steel.

Clean the block Fo8 seat, is it as flat as you can make out ? does the seat tilt ? are there any areas on the seat where the liner shoulder doesn't seat correctly when fitted without Fo8 gaskets ?

To check it correctly, when the liner shoulders are clean and the block liner lip is clean give them a wipe with good quality thinners, after a couple of minutes when dry wipe "engineers blue" over the liner shoulders (easier to apply) and refit the liners back in the order and orientation (nearside/offside and front and back) that you removed them. Clean the old head gasket and fit it then fit and  torque down the cleaned head up to 80 lbs ft . Undo and remove the head and gasket and then remove the liners keeping them again in orientation and inspect the block liner shoulder surfaces for the engineers blue, it should show a continuous band across the seat and around the complete circumference, if you don't have that then the block liner shoulders need recutting at 90 degress around the complete circumference of each liner seat. At an  engineering shop, easy to do and will take about 2 hours if a competent jig borer operator.

If you use steel liner shims it's very important the surface of them is covered in Wellseal, first wipe or paint Wellseal completely around the block surfaces liner shoulder, then paint the shoulder surface of each liner with Wellseal, then paint each surface both upper and lower of the Fo8 liner gaskets with Wellseal, then holding the Fo8 gaskets with spread fingers by their inner bores carefully position them into the block onto the Wellsealed liner shoulder surfaces, and the position the Wellsealed liners in correct orientation on top of each Fo8 gasket, push them firmly down and don't wiggle them about. Fit Wellsealed head gasket (both sides) and torque down to 105 lb ft using 3 sets at 40/80/105 (not critical as long as the final one is 105.

Oh. ...Fo8 gaskets me I use copper, I suggest you do too.

Mick Richards

[RogerH]

Hi JJC,

                       Mick normally informs all posters having these troubles to ensure that the liner is sitting square and protruding by 0.003 to 0.005" measured around four points of each liner.

Each liner should protrude the same all around - eg 0.004" at four points around a liner.

All liners should either be the same protrusion or slope down gently from front to back or the other way.

TRy not to get #1 at 0.005" and #2 at 0.003".

Very small amounts but could make a difference.

 

The liners are not ground but simply turned on a lathe.

 

Roger

[Fireman049]

Copper Fo8's every time!

Tom.

[JJC]

Thanks - that’s a workshop manual in its own right! I’ll get my expert friends to supervise. Will let you know what transpires. JJC

PS It took about 2 years I think and the FO8s are definitely corroded away

[Ian Vincent]

It's worth noting that the copper FO8 gaskets are 18 thou thick whereas the steel ones are only 15 thou thick.  You may end up with too much protrusion at the head with the copper gaskets and need to get the liners reduced in height. A simple enough task on a large with big enough chuck to take the liner.

rgds Ian

[JJC]

Mick - forgot to say the problem is radial faults, as though the casting was faulty. Will get thoughts from my friends down here and try and post a photo but close ups with the IPad are not too good. JJC

[Ian Vincent]

Pls note I meant "Lathe" in my post, not "Large".

Rgds Ian

[JJC]

A picture 

[Motorsport Mickey]

Thanks to Roger for completing the liner fitting process...I forgot to mention it  !

Regarding the photo of the liners if you are worried about the marks in the extreme bottom of the skirt of the liner...don't be. The liners are fitted free in that area and protrude into the bottom engine case without that liners bottom edge touching or sealing upon anything. 

The liners are sometimes "encouraged" out of the block from underneath by beating on them with hammers or implements ! especially when they've been fitted for some years, which can be risky. I draw them out with a substantial threaded bar with a 3/4" thick turned alloy mandrill end cap that fits inside the liner and with an outside diameter which will pass through the blocks machined spigot diameters, however as long as there are no cracks in the liner caused by impacts to the bottom skirt of it they should be fine for reuse. I can't see the liner Fo8 shoulders close enough to judge their condition and definitively the way to check them is as per my previous post.

Mick Richards 

[JJC]

Mick.   Well spotted! That’s a relief. Many thanks for the advice. JJC

[Drewmotty]

Which anti freeze are you using?  The wrong type can eat steel fo8s very quickly. 

Dont ask me how I know (doh)

[JJC]

Correct antifreeze but probably not enough. Spent the day taking head on and off and liners in and out. Trying all orientations of liners for fit within tolerance as in posts above. JJC

[RogerH]

Hi JJC,

              when I measure the liner protrusion I use a 6" length of 1/2"dia silver steel and feeler gauges. makes life easy.

Pop the liners in on top of the Fo8's, Clamp the liners in 4 places then measure.

if you get good playing with the liners you may be able to level them all out by machining a thou ior so off the Fo8 shoulder. The metal is easily machinable.

If you get problems have a look at the seats in the block - they must be CLEAN

Roger

[JJC]

Roger - we’ve been using the silver steel and feeler gauges. Unfortunately it’s not just the liners being different heights, it’s different heights across the liners. I’m trying the liners at all four orientations to see if they come closer. Done two so far. Intend to make sure the block is really really clean as that might be confusing things. But I suspect that’s just clutching at straws.

Annoying as I really want to see if my soft Surrey top stays on now!

JJC

[Ian Vincent]

Have you checked the depth of each liner from the top to the seat all the way around the circumference. It has to be consistent within a thou. 

And if it is, and you can’t get a consistent reading off the top of the block it means something in the block is out of true. Either the seat or the top surface. Either way you are going to be into some of the measures described by Mickey. 

Rgds Ian

[Motorsport Mickey]

You have to look at the liner sealing at the Fo8 shoulders and the liner protrusion above the top of the block as a package.

When these engines went together 50 years ago and were new it was a straight forward assembly of components, these days after many thousands of miles and the relief of block stresses by many hot cold cycles it's not unusual to have the liners pointing in different directions, the top deck engine surface to have lifted out of true (especially around the short studs) and the crankshaft to be running out of parallel to the deck surface.

If we prepare a competition engine we would go to great lengths to bring the engine back to it's original machined condition, "blueprinted". The engine top deck surface would be skimmed parallel to the crankshaft after the block has a dummy crankshaft fitted after being line bored. The block liner Fo8 spigot shoulders would be machined to the same depth down from the top deck surface and made to be again 90 deg to vertical so the liners would sit on them square. The liner spigots in the block which have moved out of vertical ( 1 thou out transposes into a couple of thou higher at the top liner surface 4 " away) can be ignored, the easy slide fit of liners onto them allow the now recut Fo8 shoulders to present the liners square at the top surface. Then the liners can be seated onto new copper Fo8 gaskets, measured and the heights adjusted by machining so the liners give a consistent height above the block between 2 and 5thou, ie 3.3.3.3 or 4.4.4.4 or 5.5.5.5 avoiding the low spots often measured on todays engines on the inner liners ie 4.4.2.4 which can allow a reduced gasket clamp and future weak spot.

However, to arrive at that condition needs a number of machining rectifications and an attitude to many part engine rebuilds and measurements with a corresponding increase in cost and a relentless attitude to measuring and correcting out of true dimensions as identified. Many 4 cylinder TR owners would prefer to build the engine once without hardly any measurements, that can often lead to a badly set engine and future reliability problems, BUT all is not lost.

There is a halfway house, these engines are design classics and have the advantage with removable liners of being almost infinitely variable in dimensions as long as you can measure and then adjust them. Through the 60s and 70s Many were used by impecunious TR owners as their only car and EVERY component can be exchanged or removed and then replaced at the roadside, with your car in a garage an easier time will be had.  

Continue to fit and measure the liners onto dry fitted Fo8 gaskets to orientate them to their best condition. When you think you are at your best compromise of dimensions use an old head gasket and using the head clamp the liners down using at least 80 lb ft to ensure the liners are seated correctly, then remove the head (get used to this) and head gasket and secure the liners down with large washers where the liners are siamesed together ie  oo oo  (old gudgeon pins onto the large washers on the head studs does the trick), torque down to around 40 lb ft, you don't want the liner position to relax without any load on it.

As has been said measure around the liner in 4 positions, I use a depth micrometre but the feeler gauges will give repeatable figures as long as used carefully, write the dimensions down onto the liner top where measured then stand back and make your decision. Obviously the lowest liner height over the deck is the datum position and all other liners will need to be removed and machined down to give the same height above the engine deck that can be achieved with all of them between the 3 and 5 thou dimensions. Mark the liners 1/2/3/4 inside the bore and their orientation, from now on these liners ALWAYS go into the engine in the same position front to back and left to right. Then rebuild the engine again onto the dry fitted Fo8 gaskets as previously done, refit the head gasket and cylinder head torqueing down to 80lb ft and remeasure the liner heights above the block. Now you should have an engine with liners sitting at the same height from the engine block which you chose to build at,  carry on and remove the liners and refit the Fo8 gaskets with Wellseal as itemised previously, fit the new head gasket and head.

Mick Richards

 

              

[JJC]

Thanks, these posts would make an interesting article! I’ll read them several times and then stand in the garage and ponder. I am fortunate in having expert friends but your posts really are a huge help. The car is a million miles from competition, more like the pensioner’s Sainsbury’s run. But nevertheless I want it to be reliable, I need my groceries.

Yesterday we got quite good at taking the head on and off, only trapping fingers once. Just dawned on me I do have a straight bar drilled for the very purpose of clamping liners. I can use that to settle the liners for measurements rather than the head?

I will get a set of measurements in all orientations then think about it. Do the measurements all have to be within a thou or is a thou difference acceptable? I can see that 5225 wouldn’t be at all good but how about 5445 or similar? In other words what can I get away with? Especially if I find copper Fo8s 

Many thanks

JJC

[Motorsport Mickey]

No, using anything else other than the head to pull down the liners is very risky.

Using an old head gasket and also the head mimics the final configuration as close as can be achieved, if there is any variance on the liner heights the copper head gasket allows it to conform but still imparts a clamping force. If a solid bar is used it clamps what it touches, that means it will only pull down the high liners, if there are liners a couple of thou or even one thou less in height they will remain not clamped onto the Fo8 gaskets allowing for mismeasurements to be made which then compromise the final fitment and reliability.

Beware of seemingly innocuous shortcuts, the build/measure/machine... build/measure/machine... process is repetitive and seemingly tedious but it's intention is to isolate and then finally eliminate the incorrect dimension within the engine.

 The liner height variation need to be minimised, as said if time and inclination are available a straight set of 5s or any dimension down to 3s are available, however if I break down an engine with mis-set liner heights it's always more critical if they are either of the inside 2 liners. The majority of the time it's number 4 liner which is low, it runs hottest of the liners (furthest away from the pump and supplied with water which has cooled liners 1/2/3 first ) and so the rear of the engine stress relieves most and the block material there becomes more malleable and does lift (after 50 years). So you often find a No 4 liner with only 2 thou height over the block surface, if that was an inner liner I'd be worried, the liners either side making fulcrum points and preventing the head deforming to give the same clamp pressure on the gasket as exists either side. However at either end of the block there is no outside liner fulcrum and so the seemingly impervious 3" thick casting will deform there giving a more approximate clamp to that which exists on the inner liners, years later you will often find these engines running happily.

Really try to achieve a more even liner height, don't even blink at removing liners to equalise the heights (make sure you have the copper Fo8s and have measured everything first to know which liners need what off) given you are using feeler gauges if you can measure a thous difference I's say you are doing ok but 2 thou would need amending by grinding the liner or turning it off.  You'll often find an Auto build shop a little "uncomfortable" if you ask them to remove 1 thou, often their equipment is "worn" and worse than that operated by jobbing mechanics, wheras a pukka engineering shop will undertake these small machining amendments more readily having the equipment and staff more able to do it.      

Mick Richards

[Ian Vincent]

As a matter of interest, where are you?  If you are in Devon, I can direct you to a couple of firms that know what they are doing. (and one that doesn't!)

Rgds Ian

[iain]

What a great description Mick......

not something I did personally ,but relied on the skills of an extremely good and TR familiar engineering shop to do this for my rebuild.

I can highly recommend Hamlin in Bridgewater.

 http://hamlinsengineering.co.uk/

Iain

[Nigel C]

I'm going to throw a question in at this point. Is it wise/worth while boring out used standard triumph liners in stead of buying new?

I ask this because when I bought new liners 65,000 miles ago I was told by supplier that " of curse these are only any good for about 60,000 miles before you need to replace and rebuild as they are largely made out of monkey metal". I was shocked/disappointed/p*ss*d off to be honest...but as it turns out, he was right as it does seem tired now and I am, at this point in time sweeping together enough parts to build another engine so I can just swap it over.

I have a set of ST 86mm liners and thought of machining out to 88mm? I have mates who restore motorcycles and they seem to machine liners as the norm?

 

sorry for the hijack!

[RogerH]

Hi Nigel,

                I have used a number of new liners and would suggest they were at the bottom of the cost chain. Probably County liners from TRShop

They have lasted easily more than 100,000 miles before I chose to replace them simply because it was simple to do - but not necessarily essential.

Would I buy them again - certainly.

If you go down the 'opening out' of existing liners then why not go for 87mm as that is a common size.

 

Roger

[JJC]

Chaps - as ever the Forum provides great help and entertainment at the same time. 

I got the same answer from my expert friend about having to use the head and not using a bar.  Pity because the head is very heavy at arms length. It’s already been on and off at least three times. Anyway, thanks Mick for the very clear explanation on tolerances. I’ll persevere and let you know what happens.  

JJC

[Motorsport Mickey]

" when I bought new liners 65,000 miles ago I was told by supplier that " of curse these are only any good for about 60,000 miles...turns out, he was right as it does seem tired now and I am, at this point in time sweeping together enough parts to build another engine so I can just swap it over."

Not as expensive as you think Nigel, just fit a new set of piston rings. IF you think the performance has dropped off it can only be from reduced piston ring radial loading ie the pressure between ring and wall has reduced allowing " bleed past" of compression and a compromised power stroke. For maximum power the engine piston to cylinder clearance on Pistons of this size can be set at 5 thou ( forged Pistons) or 4 thou for cast, as long as your engine is within these tolerances replacing the piston rings will recover the radial compression and with it your missing...zip. Whilst the head and sump is off glaze bust and hone the liners and then bed the new piston rings in with BMEP* running, even better you can do this refresh in a day without pulling the engine and without disturbing the liner heights by removing them.

Mick Richards

* Brake Mean Effective Pressure