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13 hours ago, RogerH said:

Hi Rob,

I was suggesting getting the Moss 86mm and getting it rebored to 89.

But I still think that Steve's broken liner will still do the job.

 

Roger

If buying a 86 mm bored liner be sure you check the external diameter of the waisted area.  Something tells me the 89 mm is a bigger diameter to the 86  to maintain a wall thickness. So it does not crush in that area when torqued down. 

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On 10/3/2021 at 10:57 AM, Motorsport Mickey said:

15 Thou minimum gap to prevent binding against the piston, as to max gap, there is hardly any too big. Stagger the gaps if it makes you happy ( I do) confident that within the first thousand miles they will move in the piston, nobody cares. Do a search under piston rings and all is revealed. Yes small step to the top ( it’s a ridge dodger).

Mick Richards

I have just realised that Mickey stated ring gaps of 0.015, I did all mine at 0.008 as on the triumph manual it states 0.003 to 0.010. What are everyone's thought on this? IMG_20211004_203540.thumb.jpg.770d64f9b3187571b15315144804f73d.jpg

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If you get the piston ring gap clearance too small by 1 thou...you will break rings. If your clearance is greater...there is no downside. As suggested above many times, a forum search will reveal all.

Try this from the forum

http://www.diagnosticengineers.org/journal_ articles/Ring Gaps vs Knowledge Gaps.php

I'm on engine build 24 and that 15 thou is what all mine are done at, but you may like to plough a different furrow.

Mick Richards

Edited by Motorsport Mickey
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Hi what an interesting link, I have also contacted Hamlins who did the machining work who advised 0.003" to 0.004" per inch diameter of bore which lines up with the suggested 0.015“. So I have got another job to do... Pistons back out sort out gaps again ffs.  At least I will get to use my new piston ring pliers. 

Thanks for all the help

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Concur mine also from TR Shop were all exactly the same at just over 16 thou.

I have been told that all the currently supplied 89mm pistons/liner kits sold by the TR suppiers (Moss, TRGB and so on) are from the same source.  Still important to check the ring gaps are over 15 thou. When the engine gets hot the rings will expand and if there is inadequate clearance there will be nowhere for the expansion to go. Broken ring.

I would ring around the various suppliers and see if they have an orphan liner. It might just be that some of those who build engines may have damaged a liner and opened a new pack to replace it or had a customer buy a one off for the same reason. I would be reluctant to re-use the damaged one without getting it crack tested, smothing the edges of the damage to minimise any stress points from forming cracks and propogating in the future and being certain that it is well BELOW the area swept by the piston.

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"being certain that it is well above the area swept by the piston."

Wrong way around Andy, the piston skirt nearly (depends upon which piston design) protrudes BELOW the liner skirt where the chipped area is. But the piston ring area where the compression is formed is positioned above the chip (I hope), so as long as the stresses don't flex the piston skirt too badly the liner MAY not develop a fracture which runs into the waterjacket.

Nope...I'd be paying £80-£150 for a replacment liner not to HAVE to strip the engine in situ with the attendant work (10-12 hours depending) if the liner develops a crack.

Mick Richards 

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21 hours ago, Motorsport Mickey said:

"being certain that it is well above the area swept by the piston."

Wrong way around Andy, the piston skirt nearly (depends upon which piston design) protrudes BELOW the liner skirt where the chipped area is. But the piston ring area where the compression is formed is positioned above the chip (I hope), so as long as the stresses don't flex the piston skirt too badly the liner MAY not develop a fracture which runs into the waterjacket.

Nope...I'd be paying £80-£150 for a replacment liner not to HAVE to strip the engine in situ with the attendant work (10-12 hours depending) if the liner develops a crack.

Mick Richards 

Very sound advice!

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  • 2 weeks later...
On 10/3/2021 at 7:01 PM, BlueTR3A-5EKT said:

On the chipped liner. 
Dye penetration inspection and smooth out the crack edges.  Check the piston does not drop lower than the chip    If happy maybe fit and forget 

The method i used was to spray the area with red maker dye, wipe with  rag and thinners  and them dust with talc, worked a treas but next time ill make sure i have the spray indicator !!

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Just to follow up ... I checked the liner for cracks and there was an inch crack so its the wine cooler option..  So I striped the engine as i was also concerned that the timing chain felt stiff . The Chain was beyond **** .. Id replaced the crank gear and added a vernier cam gear , so set the valve timing   with  first to liners fitted and it was a great deal easier to set up. I replaced the timing chain used a heavy duty chain  the Moss standard chain was rubbish , used a Racetoration chain tensioner  ll went back together really well . 

The TR shop quoted  £58 plus  postage for a liner and  Racetorations  £48 plus post and vat . Spoke to Daryl  about the liner and if it hadnt  had the crack they would have used it  .

The liner came in a County Motor Vehicle  Comp box  with made in India  by www.atracparts.com  who seem to know what they are doing 

all the best 

Steve

 

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50p says they are from the same supplier!

The better chain supplied by many of the usual culprits is apparently less prone to stretching and made in Germany.

Presumably the liners are strong but brittle. 

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. A think you have hit the Nail on the head Andy .. There are some good engineering companies in India   and i think the supplier is one .. The chain   i fitted is a German one no tight spots and no noise when turning  the engine over . The Moss cheap version  was  garbage in comparison to the German Chain Attached are  a couple of photos of the step in the top of the piston ring .. Nothing in the instruction   sorry they are not better photosIMG_6592.thumb.jpg.4a0b112fc57c70e9074b833c71e4b0f2.jpg

C401945C-38EF-45EF-8EB6-491F907B2E22.JPEG

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Hi Steve,

 to be fair to Moss they sell both cheap and expensive (quality)   both timing chains

I once had a meeting with the top men ad suggested they throw the cheap stuff away and ONLY sell quality.

They said they would go out of business pretty damn quick.  Contrary to what people say on here cheap is the order of the day.

If there is no Moss then folk will turn to Ebay.

The new 4 pot cranks are a work of art and cast & rough machined in India - top quality..

 

Roger

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Hi all, been away for a couple of weeks so just got back into the garage to start removing pistons so I can sort the piston ring gaps at 0. 0015". While I am taking backward steps I did have some concern regarding the fitment of the rear crank seal. When fitting this seal I did notice that one edge of the seal is not level with the other by about 0.0012" on one side, this was with the fitting tool and with the crank and bearings fitted (see photo) as the crank turned perfectly I assumed this was just an original casting / machining discrepancy but it has been bothering me for some time. The bearing cap is extremely tight. 

Is this discrepancy normal / acceptable or do I need to strip this out again and try harder, and if I do need to try again is it acceptable to only slacken off/ remove this bearing cap or do I need to release the other main bearing caps?. 

Not sure I want to know the answer but might as well sort it out now rather than later. 

Many thanks in advanceIMG_20211019_172129.thumb.jpg.1d4d891093c436b3cc2da94b5ee96de0.jpg

 

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12 minutes ago, Adrian Fuller said:

Hi all, been away for a couple of weeks so just got back into the garage to start removing pistons so I can sort the piston ring gaps at 0. 0015". While I am taking backward steps I did have some concern regarding the fitment of the rear crank seal. When fitting this seal I did notice that one edge of the seal is not level with the other by about 0.0012" on one side, this was with the fitting tool and with the crank and bearings fitted (see photo) as the crank turned perfectly I assumed this was just an original casting / machining discrepancy but it has been bothering me for some time. The bearing cap is extremely tight. 

Is this discrepancy normal / acceptable or do I need to strip this out again and try harder, and if I do need to try again is it acceptable to only slacken off/ remove this bearing cap or do I need to release the other main bearing caps?. 

Not sure I want to know the answer but might as well sort it out now rather than later. 

Many thanks in advanceIMG_20211019_172129.thumb.jpg.1d4d891093c436b3cc2da94b5ee96de0.jpg

 

Hi Adrian,

 did you mean 0.0012"  ( one thou and a tiddly bit) or 0.012"  Twelve thou.

If the first one - that is very small.

 

Roger

Edited by RogerH
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Hi Adrian,

I think I understand what you are saying.

As the seal is a very snug fit in the clam shells then there may be a problem - it should sit level side to side.   It may also be that it is so snug that it has puckered up a tad.

Another concern - have you got the gap at the 12-o-clock position???  from your pic it looks like the gap may be nearer the 6-o-clock

12-o-clock may help stop any leaks

 

Roger

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Hi Adrian

I would have thought that the two halves would be the same thickness. But then again with one being thicker it should have no effect on the seal.

Can you get a feeler gauge under the clam shell.  I assume the attachment screws are tight and yu did clean the area before fitment.

 

Roger

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Hi Roger the two halves are the same thickness, the clam shells are hard against their respective surfaces with no gaps. The lip / raised section is due to the way the main bearing cap has located itself in the casting / on the bearing, ie if you took the clam shel off you would see that the bearing cap is not aligned with its opposite engine casting. 

Hope that makes sense 

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Bit of info after the event, but where engine block end caps close off the crankcase, it’s good practice to “ dress” the bearing blocks outwards against a straight edge when fitting with a soft mallet. If an engine plate is fitted over a gapped bearing housing it leads to leaks.

Mick Richards

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Hi Mick

The main bearing/engine block end cap at the rear of the engine was not dressed up and probably should have been. Do you believe the raised clam end / main bearing position or seating is not acceptable? And dressing may allow bearing cap to fit more correctly, remembering that the crank turns as it should?. Also is it acceptable to release this main bearing only (and not the other bearing caps) to allow me to dress up the bearing cap/block end cap

 

Thanks in advance

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Yeah…I wouldn’t be happy with it Andy.

If the rear bearing cap is at least 12 thou out of line with the end of the block it’s possible the seal has a 12 thou stretch across the join line of the ends, I would worry.

The crank should be floating happily on a film of oil between surfaces, I would brace the centre main with thrust washers in it’s central float position ( angled wood wedges ?) so no damage can be done to thrust washers. Then release the torque on the rear block main bearing cap, remove the the rear bearing cap and clean out felts and Newley fitted Wellseal ( messy). Check for damage on bearing and Marx oil seal holder ( unlikely). Then using new felt and Wellseal refit the block cap with lubbed surface on bearings and Marx seal complete with blob of silicone where the seal ends fit.. Dressing block cap back to a flat edge as it drawn in and when happy with all surfaces, torque it up and check the crank turning torque.  You can compare to the turning torque measured before strip down ( remember to do it) to ensure you think all is well. Then refit new felts with Wellseal rammed in hard regularly until the block and cap join oozes it out. Leave felt at least 6mm high against block surface so sump will compress it when fitted.

Mick Richards

Edited by Motorsport Mickey
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So pistons all back out to Sr ring gaps at 0.015" silly me set the at 0.008. Now looking at removing rear bearing cap, unfortunately I have already fitted the felt soaked in wellseal. The question is should I attempt to remove this with engine on the engine stand or is it safer to get the engine onto the deck, also any tips on how to remove the bearing cap as it is very tight.. 

Thanks in advance

1634909673978.jpg

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