Liner heights

[John L]

I have been asked by a friend to help him cure a cylinder head gasket blowing problem. gasket been changed before, so sure the protrusions are not correct.

I know the liners must be proud of the block, if using a fo8 gasket of a certain thickness, and one liner is lower than its mate, how is this corrected, must you try another liner to give an equal height for both, or is there a better way?

I have seen there are some useful previous postings on here, that I will search again.

Any additional info would be very useful, I have a feeling my friend will use some new pistons and liners. but not sure at this stage which size yet.

What is going to be the best type of head gasket to use and the torque of 105lbs ft in stages. Is the std one from Moss ok?

John

[Motorsport Mickey]

Here you go John, this pinched from my post on an earlier 3a thread.

Place-car on ramps or jackstands.

 Drop oil from sump

Drop sump, drop oil pump. mop conrods and crank inside crankcase with non fluffy rag to remove worst of standing oil.

Undo big ends and push conrods up past and around the crankshaft and out of the top of the liners… carefully, no broken piston rings here or dings put into ground crank surfaces.

Repeat after me… Cling film ( sandwich wrap) is my friend.
Tear 8 pieces off big enough to wrap each big end in 2 pieces, offset so the film joints are hidden. also cover the joins around the crank into mains bearings etc with wrap to avoid dirt ingress.

If you have liners in situ for more than2 or 3 years they often form the opinion they are now part of the block…and want to stay there. However at under 12 months fitted you can make a small extractor from an alloy plug about 3/4” thick and -10 thou down on the liner inner dia and with an outer dia of -10 on the block bore and feed a 1/2” threaded rod down the liner and fit through the centre of the plugs with 2 nuts behind it, and through a heavy duty channel on the block deck draw the liners up vertical about 2” and then wiggle them out. (On holiday at present, will post photo of tool on Friday).
Obviously keep the pistons and conrods oriented And numbered 1-4.

Buy your copper Fo8 gaskets and fit dry onto the cleaned Fo8 shoulders machined into the block that you’ve now got Wellseal on. Refit the cleaned liners in order and orientation and use an old cleaned head gasket under the head and torque down to 105 lb ft.

Remove the head and measure in 2 position on each side of the liners down the cylinders and mark on the liners. Remove the liners, mark 1.2.3.4 and the front ( leave the fo8 in the block.) and have the liners machined down to leave 4 thou protrudence. Refit the liners in their position and orientation on the prefitted DRY Fo8s and using the old clean head gasket and the head retorque down again to 105 lb ft. To avoid rippling the new gasket ( when you fit it) torque it in 3 stages, 40/80/105 lb ft or similar, get in the habit.

Then recheck the liner heights, NEVER trust a machine shop. We are looking for 3.3.3.3 OR 4.4.4.4 OR 5.5.5.5 all will give a good clamping force with a copper/asbestos/copper Payen standard gasket at up to 87mm piston dia. Because of the pre noted block heat stress releasing you often find an odd thou mismatch caused by the aforementioned liner lean. Depending where it is depends upon how and if it needs attending to. Measure and advise and we can decide.

When dimensions are good refer to above posts regarding Wellseal applying, and how to refit the head.

Remove the clingfilm and inspect for dirt before replacing pistons and oil pump and sump. I reckon to do this work within a couple of days depending upon liner alteration.

If you don’t have the block liner shoulders recut square that’s the reason for measuring around the liner in 4 places ( 2 each side). You will give instructions to the machine shop ( or skim yourself with wet and dry) to skim an uneven amount off, tailoring the top surface to give an even liner protrusion around it’s circumference. That’s how I hand fettle my engines together.

Mick Richards

[John L]

Thank you for the info, as the liners haven't been out before, we are going to take out the engine out so we can clean everything.

Looking in the Moos site for the f08 seals there are 2 part numbers listed,  112789C which appear to be copper, what material are the ones without the C suffix?  Are there any different thickness of the f08 gaskets?

John

[iain]

They used to be available in various thicknesses…….. 15 thou steel, 18 and 21 in copper. Try RTR website.

[RogerH]

Hi John

the non suffix 'C' Fo8 is the standard Steel gasket.

According to the Revington site

Steel= 0.015"

Copper =  0.018"

Ali = 0.021"

 

Roger

[iain]

2 hours ago, RogerH said:

Hi John

the non suffix 'C' Fo8 is the standard Steel gasket.

According to the Revington site

Steel= 0.015"

Copper =  0.018"

Ali = 0.021"

 

 

[iain]

Just now, iain said:

2 hours ago, RogerH said:

Hi John

the non suffix 'C' Fo8 is the standard Steel gasket.

According to the Revington site

Steel= 0.015"

Copper =  0.018"

Ali = 0.021"

 

 

Expand  

The 21’s are now copper.

[Chilliman]

.................or run without figure eight gaskets & use the longer liners from Racetorations which can be machined as required. I've been running them all season in my car without issue.

[Hamish]

1 hour ago, Chilliman said:

.................or run without figure eight gaskets & use the longer liners from Racetorations which can be machined as required. I've been running them all season in my car without issue.

TR Enterprises did mine without the fig 8. Works well. 

[Andy Moltu]

What makes the seal if there is mo FO8?

[Hamish]

The liners and block are machined for the liner heights then a modern Glue/sealant is used. 

[Motorsport Mickey]

DON'T try and build a liner engine without the liner shoulders in the block being cut square and parallel in 2 planes to the crankshaft line and the deck height of the block being machined to what you need. Then the liners are glued into position in a semi permanent set, I believe the liners can be removed by machining (jig borer) down to the block liner shoulder where they were sat but not something you'll be doing at home. All this will carried out by machine shops or your local TR specialists choice of shop.

On a standard build engine the liners sit upon their shoulders in the block which was machined square over 50 years ago, the stress relieving of time and hundreds of thousands of hot/cold cycles has allowed the blocks to move slightly so the shoulders move and the liners can be leaning in various different directions. The liner "spigots" at the bottom are a slide fit in the block which allows any slight mismatch and the liners will still seal after hand fettling onto the Figure of 8 gaskets.

Ideal for home built engines, after marking the liners for position 1.2.3.4 and it's direction facing forward or back, by measuring the liner heights twice on each liner twice on each side you can remove any single liner and by sliding it's top on a flat surface (wet and dry on a granite tile etc) cope with this and change the liner height and it's inclination to get it equal with the others and parallel down the block length. Then refit into the engine and carry on with your build all as per workshop manual.

Mick Richards

Edited October 24, 2023 by Motorsport Mickey

[John L]

My friend has gone for the larger liner and piston set 89mm, will this need a different than std head gasket?

In the larger piston liner set there appear to be FO8 gaskets, it doesn't say which size they are, but I support it will be worth having a few different sizes as well.

The block has been away to a machine shop so I hope they will have checked the bottom land is square. 

John

[Lebro]

Yes the standard TR4 gasket will fall inside the bores, correct ones are available from most suppliers, at a cost ! 

If the supped FO8 gaskets are steel, I would be inclined to swap them for copper ones.

Bob

[BlueTR3A-5EKT]

3 hours ago, John L said:

My friend has gone for the larger liner and piston set 89mm, will this need a different than std head gasket?

In the larger piston liner set there appear to be FO8 gaskets, it doesn't say which size they are, but I support it will be worth having a few different sizes as well.

The block has been away to a machine shop so I hope they will have checked the bottom land is square. 

John

As Bob has replied YES a special gasket plus the shroud over the valve will need relieving or it to will hang in the top of the bore, glow red hot and cause pre ignition and running on.

Special Gasket from Racetorations.  All copper sheet gaskets are also available in differing thicknesses to get the compression correct. Try Revington.  They also do copper Fig 8  

The machine shop will want the Liners and Fig 8s to get the top of the block skimmed to suit the intended liner fig 8 protrusion measurement of 0.004" - 0.006"

Or.... Talk to Racetorations who have liners fitted without fig 8s 

 

How to relieve the cylinder head and match it to the gasket and bore is in the Kastner black book.

 

Peter W

[Lebro]

Of course relieving the inlet shroud is a good thing to do anyway,but will lower the CR. Then again going from 86 to 89mm will have increased it !

Best practice would be to carefully measure the capacity of each combustion chamber, & get them all the same.

If the block face gets machined (to compensate for any machining done to the liner seats) then the pistons may need to be shortened.

Bob

[BlueTR3A-5EKT]

Yes I am just embarking on this journey. The head a TR3 original 1991 cc one is done and the liners are 86 mm. I think the first guess gives 9.5 to 1    Challenge of refaced block will see me turning a bit off the piston crowns once I know the chamber capacity.  Memory says 53 cc is a good starting point to get an acceptable cr with standard copper head gasket.   Piston to deck height aim is 0.010”

here is a calculator.  http://www.csgnetwork.com/compcalc.html
 

[Andy Moltu]

Mick is describing how to achieve the optimum liner heights.

However if there are minor discrepancies it’s not the end of the world providing there are no more than 1 thou’ differences with no lows between highs. (The higher liners should be the middle ones, so you can have 4,5,5,4 but not 5,4,5,4

A few vendors sell a good composite gasket that works with 89mm liners.

If you do relieve the shroud around the inlet valve be careful not to remove too much. (A used 86mm gasket makes a safe template.)

[BlueTR3A-5EKT]

I’ve started so I will finish.

Imperial thou Feelers 4/5/6 to hand and a ground parallel

Clamp with head and old gasket.

Am getting consistent 5 thou diagonally.  Drag in some places, loose in others but will not accept a 6 and too sloppy for a 4

Classic and Modern did ok.

 

 

 

Edited March 3 by BlueTR3A-5EKT