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I had to remove the head on my TR4A because of coolant loss through the Fo8 gaskets. This proved very difficult because the head was binding on the O/S front stud... after a lot of sweat and consternation, it finally came free, but I found that there had been a lot of corrosion/erosion of the stud... which must have been binding on the hole through the head. It was also apparent that there was similar, but not so severe, damage to the rear O/S stud, although this was free (it actually screwed out of the block in preference to the nut simply coming free).

 

The appearance of the stud is more like what I would expect to see by some sort of acid attack... not the obvious normal oxidation/rusting (see attached pictures). From the absence of red rust I wonder if is this has been caused by some leakage from the adjacent combustion chambers. I have looked at the head gasket to see if there is any sign of channelling, but I am not sure what I should be looking for... in some areas the gasket has retained its original copper colour, but other sections are discoloured black. I tested the compression before dismantling the head... all cylinders were around 150psi if I remember correctly. The studs are near to coolant passages, but I would have expected to see signs on the gasket, if that had been the path for whatever has been attacking the studs.

 

Is this stud damage a common feature of these wet-liner engines?

 

I plan to replace all the studs, even though the damage appears to limited to just a few (to ensure that they all have the same stretch/torque characteristics). I know that ARP studs are now available, but I assume that these are intended for higher stressed racing engines, so expect the standard plain studs to be suitable for my unmodified engine. But are the new plain type to the same standard as the original Triumph items?

 

I expect to use a normal copper head gasket, with folds uppermost and no sealing compound. Any recommendations other than trying to get the liner protrusion to 3-5 thou? I will be having the head fitted with unleaded seats on the exhaust valves... I assume that the machine shop will also skim the head if they think that this is necessary. Is the head skimming process more or less essential with the TR design (protruding liners), compared with a normal cylinder bored-in-block engine?

 

 

 

 

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Hi Robin

 

Does look like you have had some water ingress that has got to the stud. But bearing in mind how old they might be, it could be from a previous head gasket leak. It would be wise to replace them, and standard studs are fine. Just remember to torque down after 1000 miles or so.

 

Skimming of the head not necessary because it's wet liner, but skim it lightly if surface uneven. No sealant on gasket.

 

Regards

 

Kevin

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Is this our old friend a crack from water way to stud hole?

The factory recommended build technique involved the use of a turn/wrap of lead linger (looks like solder wire) under the head washers to seal the studs to the head top face. To me that meant they expected water seepage up the head studs.

Peter W

 

PS This technique was on sidescreen cars - I have a roll of lead linger if you want a length to try, it is also used under the locking nut of the oil pressure adjusting screw.

Edited by BlueTR3A-5EKT
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Hi Robin,

pop down to the June meeting for a natter.

 

You may well find that the difficulty removing the head is that the front and rear manifold studs can be wound too far in and lock onto the studs.

I found this on my 4A in the early 90's.

 

As for the black appearance/corrosion I've seen this quite a lot but haven't noticed an associated leak.

It could be that the head nut/washer isn't moisture proof and over a long period moisture can get in and cause this effect.

If the bolt had a smear of grease/oil then that would add to the gunky effect.

Possibly exhaust gases getting from the manifold stud interference.

 

New plain bolts should work OK.

 

I think you will have fun removing the old studs. Start with the double nut technique and see what happens from there.

 

If I was doing my engine again I would have the block acid cleaned and have the Fo8 seats in the block looked at.

Machined parallel to the top of the block if rusty.

You will probably need to have the top of the block machined flat (this will compensate for the material removed from the Fo8 seats).

 

Good luck

Roger

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Thanks to all for the suggestions. Intrigued by Kevin's comments about a crack between the waterway and stud pocket... I had wondered about this as a potential source of leak... especially on the front O/S because of the proximity of the opening to the water pump (so thicker casting does not go all the way down the block). Is this crack a well known issue?

 

I noticed that the coarse threads on the block end of the studs have vertical cuts (like a one-land thread-tap). I assumed that this is there to relieve pressure from below the thread, but I have not noticed this on any other studs around the vehicle... so any suggestions?

 

Having another look at the block, it does appear that the centre O/S stud also has some corrosion, but none on any of the N/S row (which are located inside the rocker cover). This might suggest something getting in from the atmosphere.

 

Must own up to not being so conscientious about antifreeze in the past... the car has always been garaged and never used in winter. However, I now also own a Triumph Stag, so I am totally paranoid about maintaining the correct strength of antifreeze in that (I even have a hydrometer!), so I think that the TR will get the same care in the future.

 

Acid cleaning of the block would be nice, but this work is being done with engine in the car... just completed a 18 months out-in-the-open refurbish of the Stag and I could not face another protracted session.

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The lengthways slots in the cylinder head stud threads are there to relieve hydraulicing if oil or other fluid (water) is trapped below the stud when being fitted.

Have no fear with these engines, they are hewn from granite, as long as you are relentless about getting the correct liner heights (check the search facility, there's 7 or 8 threads with how to do it) they will give starship mileages and as a measure of pure unadulterated brute strength how many other classic car engines will give you over 100% increase in power with reliability. Part of the attraction of a removable liner is the ability to complete an almost full engine rebuild with the engine in situ, cover crankshafts with a plastic sheet (clingfilm is good)and you can forget **** falling on it, drop the sump to enable pistons can be removed.

As a Stag owner myself (they are pretty but fragile) I understand the hand wringing that accompanies engine problems (if you havn't had them yet, you will) however you may be familiar with K Seal often recommended for Stags to seal their weeping surfaces and this works well also with the TR 4cylinder engine. Because it has a suspension of extremely small copper and other particles in it, it searches and seals minute cracks whilst flowing happily through larger waterways in pumps, radiators and heater matrixs. I've built over 20 of these engines often for race use and have no compunction in using a water jacket sealing agent with no ill results.

 

Mick Richards

Edited by Motorsport Mickey
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Mick, Thanks. I'll look into K Seal. I have always had an aversion to cooling system leak prevention products since using something years ago on a Triumph Herald. The whole system sealed so well that the radiator became blocked and the car began to overheat after a few miles. Luckily I was able to pick-up a Vitesse spare from somewhere along the journey... wider, but with the same mounting points and hose connections. Happy days.

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As an additional question: In Roger Williams' book; How to improve Triumph TR2-4A, there is a picture with a note pointing out how the tapped stud holes on a modified block have been recessed. I don't think that he gives the reason for this additional machining, but I assume that this is done to set the transition between thread and plain shank to a point below the face of the block (reducing a stress point). Is this a common modification?

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The studs sold by Moss are anything but "standard", according to Pete Cox (and he should know).

They are produced to the original specification, with the correct grade of steel, by the same method, and to the various (different) lengths - hence their cost.

Use of any other sort of steel could be false economy and a recipe for disaster.

Ian Cornish

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Hi Ian,

 

"anything but standard" . . . . . ? :blink:B)

 

On the contrary, that sounds to me exactly like standard, as in factory standard, as in OE Standard Triumph specification. :rolleyes:

 

Come on old chap, we can both be pedants, let's not further devalue the word "standard", whether with upper or lower case 's' . . . . . :P;)

 

Cheers

 

Alec

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As an additional question: In Roger Williams' book; How to improve Triumph TR2-4A, there is a picture with a note pointing out how the tapped stud holes on a modified block have been recessed. I don't think that he gives the reason for this additional machining, but I assume that this is done to set the transition between thread and plain shank to a point below the face of the block (reducing a stress point). Is this a common modification?

The reason is to help avoid the cylinder block material being lifted as the cylinder head is torqued.

The imposed and transposed block loading of the 105lb ft torque down the studs malforms the block locally. On the original block set up ( earlier Vanguards I think etc) ALL the studs were of the short variety and they suffered from the block "lifting" around the base of the studs, hence relieving the clamping pressure and causing gasket failure. The revised blocks with the central studs being deeper into the block (no space or material to do it on the outer studs) help prevents the block deforming. The machining of a substantial chamfer or counterbore helps prevent the shorter studs "creeping" the material up the studs, although interestingly the factory didn't think preparing the blocks as per this was worthwhile. (in their defence the factory wouldn't have thought we would be driving their products 61 years later !).

 

PS: I've never used any studs other than the original factory items. Where there's been a damaged stud (normally when removing from a "Titanic" block) I've replaced with other original studs checking the threads carefully for any "galling" (where the thread material has been "dragged" by being clumsily fitted with "swarf" or other foreign objects in between them).

 

 

Mick Richards

Edited by Motorsport Mickey
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Alec: I used "standard" (inverted commas) because RobinTR in his post #1 said:

.... expect the standard plain studs to be suitable for my unmodified engine.

Hence, I wanted to make it plain that Triumph, and now Moss, supply studs which, although standard, are actually rather special as they are to OE specification.

Ian Cornish

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...Here's one that'll screw your head.

 

When doing our aircraft inspections at BA we require a 'test block' to simulate what you are looking for and to calibrate your instrument.

The manufacturers - Boeing etc - specify these test blocks.

They refer to them as standards.

If you make your test block to represent this standard it becomes a sub-standard as far as the Americans are concerned.

 

I know what they are getting at but they can't see the odd twist in the words.

 

Roger

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...Here's one that'll screw your head.

 

When doing our aircraft inspections at BA we require a 'test block' to simulate what you are looking for and to calibrate your instrument.

The manufacturers - Boeing etc - specify these test blocks.

They refer to them as standards.

If you make your test block to represent this standard it becomes a sub-standard as far as the Americans are concerned.

 

I know what they are getting at but they can't see the odd twist in the words.

 

 

Back in the 70's I was an inspector in the Standards Room at Hawker Siddeley. We controlled all the metrology on site with various standards and measuring machines. Must have been millions of £'s worth in todays money. Often wander what happened to it all. Probably sold as scrap.

Alan.

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Just to clarify that, by standard, I did indeed hope that items like the Moss studs would be to the OE specification. It is just that I have heard a lot about the poor quality of some current replacement parts in the classic car movement... which I have experienced mainly by terrible short life on rubber items. I did not want to experience something similar with a critical item like the head studs. Furthermore, I had noticed that ARP studs are now available, so I wondered if one of reasons for these might be that the original design of studs are not to OE specs. of if they offer genuine improvement over standard (OE items).

 

I was interested in Mike's description of localised deformation of the block. I have noticed this around one of the front studs... I had planned on carefully dressing this slightly raised area back to the level of the block, before reassembly but is there a better solution without having to take the engine out and to a machine shop?

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When looking at studs be it reusing old or new, the main part which needs to be good is the thread and following on from this some high quality nuts. 105 ft lbs of torque is no good if its lost in friction between the stud and nut. It's clamping force which seals the head to block and worn nuts will ruin new studs and worn stud threads will result in pulled studs before 105 lb ft is reached.

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If you check the search facility for liner height postings you'll find chapter and verse on it.

 

Bottom line is the cylinder head beyond liners number 1 and 4 does not have support, and the seemingly thick 3" cast head deforms under the stud torqueing deflecting the head down. The block around liner 4 runs hottest (furthest from the water pump)and so is most "heat treated and stress relieved by countless years of running, this allows the block to lift easier around the short stud. Liner 1 is next hottest (closest to the water pump...too close it pushes the water past before absorbing enough heat) and a similar process with head deflection happens there also. If there are different liner heights between liners on the inside of the liner extremes ie liners 2 or 3 as per this 4.4.2.4 the reduced liner clamp on the head gasket at liner 3 (the head can't deform because it's supported by liners either side)is a likely gasket failure point. Wheras a reduced liner clamp on the end of the engine ie liner 1 or 4 because of the deforming cylinder head compensation will likely run for years.

I have fettled "cooking" engines fitted in my car by dressing the high areas at the end of the block and reclaiming a better liner height, after all it's normally only a couple of thou. There is no high compression seal required beyond the end liners, only the water jacket and oil splash from the camfollower buckets. As long as you feel comfortable with your engineering skills (I'm a time served toolroom engineer) the surface can be scraped flat in the time served manner, 25 scrapes to the square inch, or even filed and hand ground, but you do need to have the skills to do so, decisions yours.

 

Mick Richards

Edited by Motorsport Mickey
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  • 4 years later...

Do you have an engine lifting eye on the rear rh stud?   If so one of the studs is a special length to allow for the thickness of the bracket.
Sounds like they’ve added a spare stud for that application & looking at Rimmer price they have ‘given’ you the extra stud in the kit.

Peter W
 

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1 hour ago, BlueTR3A-5EKT said:

Do you have an engine lifting eye on the rear rh stud?   If so one of the studs is a special length to allow for the thickness of the bracket.
Sounds like they’ve added a spare stud for that application & looking at Rimmer price they have ‘given’ you the extra stud in the kit.

Peter W
 

But are the Rimmers studs the same quality as the Moss studs ?

Mick Richards

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1 hour ago, Motorsport Mickey said:

But are the Rimmers studs the same quality as the Moss studs ?

Mick Richards

ooo you little tease!

I'd ask the same of the hardened washers and grade 10  1/2" unf washer faced nuts

Peter W

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