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TR4A Engine Rebuild


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On the subject of the mandrel.

The workshop book dimensions for the mandrel, I assume, were calculated with consideration to the dimensions of the split Ali seal plate.

The revised smaller dimension for the mandrel may well bring the two split plates closer together but only for the 12 & 6-o-clock positions.

Obviously the 3 & 9-o-clock positions would be virtually unaffected.

 

However on the bright side the majority of the oil for scroling back would be at the 6-o-clock position - certainly at start up.

 

Thinking sides again - why have a gap at all between the scroll and the Ali plate.

If the Ali plate was a very snug fit then the scroll would soon make it a very nice running fit once set in motion as per aircraft engine design.

 

Roger

Edited by RogerH
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Hi Roger,

 

I believe the Ali plate if inspected will show a machined scroll on the inside of the collar that abuts the crank scroll.

 

I have a collection of Ali plates removed from engines on strip down that have been "modified" by the crank by contact with it in just such a manner as you suggest, some to the extent that almost all traces of "return" scroll that is machined into the collar of the Ali plate has been removed. I replaced them with other Ali plates with as crisp a machined scroll in them as I could find (never throw anything away).

 

If you only have a scroll on the crank which is working it may be that it contributes to excessive oil standing on the crank surface when the engine stops which then allows our infamous "seep" back, only my theory.

 

Mick Richards

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.

 

Isn't Welseal wonderful stuff. A little dab gets everywhere - nose, ears, hair and some on the engine.

 

Roger

 

Hi Roger, I too find Welseal gets everywhere, except where you want it to stay to seal the flippin' joint!! ... I recently fitted one of the split lip rear seals as supplied by Revingbone, .... good piece of kit, it's worked perfectly, ... in their instructions they recommend Heldite a quick drying liquid sealant that you paint on both surfaces, or screw threads, or whatever, .. anyway it's proved to be really good stuff and I wouldn't hesitate to recommend it, at least it stays where it's supposed to be!!

Cheers rob

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Today the Welseal stayed in its box. :)

It was time to install the cam bearings.

On the TR4 enigne that I did two years ago I made a little gadget to align the locating hole before pressing the bearing in. ;)

Today I forgot I had that gadget :(

So I made a bigger. better, much improved super duper bearing installer - see the pic.

This allowed the bearing to be aligned on the press tool and the tool aligned with the alignment hole in the block.

It was a little fiddly but worked - three bearings out of three attempts - top marks.

 

Tomorrow, liners/pistons.......

 

Roger

 

The bearing slides over the small diameter up against the large diameter.

The screw has a squared off end that fits into the alignment hole in the bearing. This passes through into the alignment groove in the tool.

The back face of the bearing has a feint line scribed in it to align with a similar mark on the tool.

The screw is then inserted into the block and the tool aligned with the screw.

The screw is removed once the bearing gets started.

As the bearing is screwed in the alignment marks on the back of the bearing are monitored - but they shouldn;t move.

Edited by RogerH
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Niall, 'you are naughty; but I do like you' (apologies to Dick Emerey).

 

I am now nailing all the bits onto the block - some in the correct place.

 

In fitting the front engine plate the WM say fit the dowels 2off. I have two dowels BUT there is only one plain hole in the block that would take a dowel.

The position for the other dowel has a thread.

Could it be that the dowel only sits in the plate and not go into the block

 

Another interesting oddity. The cam is original as is the cam wheel. There are two shims on the crank behind the crank pulley 2 x 0.006"

With a straight edge between the cam gear and crank pulley the crank pulley is toooo far forward.

I removed both shims and the crank pulley is still too far forward. I turned 0.015" off the crank pulley and it now lines up. Most odd.

 

 

Tomorrow I shall pop the pistons in, clamp up the B/E's and sort the timing.

 

Roger

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In fitting the front engine plate the WM say fit the dowels 2off. I have two dowels BUT there is only one plain hole in the block that would take a dowel.

The position for the other dowel has a thread.

Could it be that the dowel only sits in the plate and not go into the block

 

 

Roger

Hi Roger,

 

There should be two holes for the dowels in the block.

 

Photo below shows the positions.

 

Cheers

 

Graeme

 

Engine_036a_zpsc11e86a0.jpg

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Back to the centre cap and ? wrong way round, the block and the caps should all be labelled with a letter and numbers eg W56, all the labels will be tha same way up. This will confirm which way round the cap should go.

The imprints are quite feint and can get lost , but should be findable once you start looking

 

Michael

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Hi Michael,

the front and rear caps are obvious where as the centre one could go either way round. There are not marks, or none that I can find on them.

Thankfully the centre cap really only fits one way round.

 

Roger

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Today the plan was to fit the pistons into the block.

I have a very natty ring compressor- works everytime - and it is in the garage somewhere :huh:

I looked high and low, in cupboards, boxes, drawers. After about 30 minutes I was standing exasperated in the middle of the garage wondering where to look next.

Out of the corner of my eye I could see something waving at me, yes the little blighter was hiding.

 

Anyway armed with all the tools (steady Niall) I popped the rings on - quite oddly they all went on the right way round first time.

 

The ring compressor did its job perfectly. After I finished with it it scampered off and hid again - bless.

 

On with the big-end shells (including bearings - I'm getting good at this) - and torqued the bolts up.

This is where I had a head scratch moment. My TR4 workshop manual shows lock tabs on the bolts. But none came off and it is a TR4A engine.

So my quandry was - can I refit the bolts that don't require lock tabs.

After a few minutes talking, discussing and arguing the point with myself I decided to make some lock tabs (it's a sunday and shops are shut).

 

I then fitted the oil pump (including its gasket ;) ) and then the seive.

I then attempted to fit the sump. There was a metalic clonk and a 1/2" gap on the sump flange.

Did you know that if you put the seive on 180' out the sump don;t fit. :huh:

 

Tomorrow - the timing chain and timing set up, water pump, and possibly the head - it's getting exciting :P

 

Roger

Edited by RogerH
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Roger

 

I believe there are 2 types of bolts for the caps , the stretch type without locktabs, or non stretch types that need the locktabs

 

Cheers

 

Alan

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Hi Roger,

 

I think you have a problem.

 

The connecting rod bolts on a late TR4's and all TR4A engines do not have tab washers as they are tension bolts.

 

These bolts must not be re-used and certainly should not be fitted with tab washers.

 

Thus a set of new stretch bolts are required.

 

Always best to check the Moss bible - it is all explained chapter and verse.

 

Sorry for the bad news.

 

Regards, Richard

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Hi Roger,

 

Definately agree with Richard, no lock tabs. I think you would be OK reusing the bolts, but best to fit new ones.

 

Cheers

 

Graeme

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Hi Alan/Richard,

good point. I need to look in the box of bits that the engine arrived in for any lock tabs to establish what I have.

 

I have a problem with these 'stretch' bolts. All bolts will stretch to some degree when torqued down.

All bolts that stretch within reason will return to their original dimension unless they have exceeded a certiaqn point when Youngs moduls takes hold and they stay deformed.

in my mind 60 ft/lbs will not stretch a 7/16" diameter steel bolt.

 

if a stretch bolt has a lock tab then it may want to cycle with the heating.cooling of the tab, 'but' the tab is holding it closed down.

 

So I have a dilema - do I trust my feelings or do I follow the Moss Cat. Thinking time.

 

Roger

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Interesting subject. I have done a search in various places and the use of a tab washer on a 'stretch bolt' is a no no - still working on that one.

However the reusing of used stretch bolts appears normal. Some people use stud lock to hold in place.

One person had holes in th ebolt heads for wire locking although no wire present.

 

Tomorrow I shall sort through all the bits to see if I have tabs to indicated one way or the other.

 

More head scratching.

 

Roger

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Hi Roger,

 

I know you are a man that likes to dabble - examine, investigate, re-construct, re-make, upgrade wherever possible, however I think your thought patterns are getting rather confused on this matter.

 

If any of the alternative methods that you are now considering actually worked with certainty, I have to ask why then did Triumph not implement it...??

 

These bolts are stated as being a one use item - it would be a costly failure if a con-rod were to go.........!!!

 

Your next problem will be what are you going to use to fix the flywheel to the end on the crankshaft - again on late TR4's and all TR4A's one use tension bolts are used...???

 

Regards, Richard

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Roger,

 

As entertaining as reading your agonising is and comparing the varied comments placed by varying supporting bloggers, this really is hard work.

As regards why Triumph did not do this or that ! ! ! ...they were a commercial car manufacturer, their profits were measured in pennies, and often their losses in hundreds of pounds per car, that's why they are not making cars today ! The engineering decisions were often corrupted by the treasury department saving pennies that often came back to bite them in the bum. Hence decisions taken to replace more costly quality multi use bolts with stretch items that we would only use once.

 

Cut to the chase, just fit Unbrako socket heads or ARP bolts to the rods and main caps if you wish (that's what I do for race engines), and give it a splash of Locktite to ensure their continued tightness. I've reused these items at least 4 or 5 times on an engine and had no failures or significant stretching (when inspected visibly) of the bolts. Job done, they are not even expensive when compared to many of the items being put into the engine as a norm, alloy rocker covers etc.

Also for the unasked question... Yes I also use the Unbrako socket heads for the fixing of the flywheel to the crank, again with a splash of Locktite...I value my ankles too much !

 

Mick Richards

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Hi Richard/Mike,

I can see your points perfectly - and tomorrow I will almost certaInly have a pocketful of new bolts but I do like to get my engineering head around the problem.

 

Why did TRiumph go from HiTensile tab washer bolts to HiTensile 'stretchy' bolts - surely it couldn;t have been to save on the tab washer.

 

Another point I need to get to grips with is - although they are HiTensile bolts they don't lead a particularly HiTensile lifestyle.

The two most strenuous parts of the cycle is the compression and combustion strokes. The end cap/bolts are not under any load as such.

The induction stroke now puts the bolts into tension but not extremely high levels.

 

To go off topic slightly - the flywheel bolts would be under shear load rather then tensile

 

Still head scratching

 

Roger

Edited by RogerH
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Roger, why wouldn't they have made the change to save on the tab washers? Apart from the cost of the washers, they had to be fitted and bent up, but before that they had to be purchased, stocked, stock levels maintained, etc.

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Aaahhh Roger, the curse of new engineering thinking.

 

Stretch bolts were amongst the very earliest part of new wave engineering thinking, rather than having old fashioned "bloody ell, these are well over the top" bolts which although well over the top in quality required tab locks to ensure they would not slacken and lose their clamping action.

 

The thought process (I imagine) went something like "these new stretch bolts are cheaper, higher tech-because they stretch under torque which prevents them loosening and needing lock tabs and the necessary extra time required to pick and fit them...lets use them" ! To be fair the clamping action of these bolts over time have been proven to be as required and as long as they are not reused ad infinitum (who amongst the development engineers thought that these engines would be running 50 years later ! ) their performance has been at least satisfactory. However we now have quality bolts which can be used that will exceed by a margin the clamping action and reliability needed for the job.

 

Sometimes it's harder to try and work out the why and wherefores rather than use technology now available to circumvent the problem.

 

Mick Richards

Edited by Motorsport Mickey
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hmmm, I'm now getting concerned. AlanG has got a thread running on 'using Loctite on the stretch bolts' for the flywheel.

He raises the concern of quality of some of the products from the big suppliers - are we happy that they are selling stretch bolts or just B&Q specials.

 

I know the bolts that I have are not broken (cracked etc) so the only concern is whether they will loosen and fall out - is 'thread lock' the answer.

Or better still wire locking as this will not have any affect on the threads.

 

Roger

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