Mk2 Engine Rebuild going into a Mk1 GT6 by a novice!

[AidanT]

3 hours ago, Pete Lewis said:

ive seen new engine shells that have debris embeded  those look fine , i would be happy to reuse if thats a help

not sure what those scratchy marks are in the bore    doesnt look nice 

I think that's just the brake cleaner that's not wiped off and has dried again

This was just an initial clean

Aidan

[AidanT]

Noticed the pic above isn't great, will take another tomorrow 

I am marking everything up inc orientation 

Question

Looked at the manual again, but what should I do next?

 

Thx 

Aidan

[johny]

Its got to be main bearings. Certainly the middle two are easy and interesting to see their condition. You could replace them to keep the crank in place while inspecting the other two but I assume youre doing a complete strip? 

[thescrapman]

Now you have taken the piston out you may need to hone the bores and fit new rings.

I haven't twice now and ended up with ver y heavy oil consumption, Andy the. Someone told me not to take pistons out.

[AidanT]

25 minutes ago, thescrapman said:

Now you have taken the piston out you may need to hone the bores and fit new rings.

OK, sorry but what's the difference between hone and re-bore?

I'm really getting a little confused with this now.

Can take the block along with crank and pistons to a local machine shop, well saying that, I will probably need some help  it isn't next door!

But then new pistons? rings? How do I know what to get? Or do I trust the machine shop to do it for me? 

Grrr too many questions!

[Iain T]

Aiden, simply put honing puts a cross hatch pattern on the bore to aid lubrication of the rings to bore and a rebore removes metal from the bore to remove scoring etc. With honing you can use your original pistons with perhaps just a ring set change. A rebore requires new pistons/rings as the bore diameter is increased. 

Honing is performed when the bores are OK for size but you always hone after a rebore. A competent engine shop will advise the best course of action. 

Forum guru's correct me if I'm wrong! 

Iain 

[johny]

Agree👍 

Bores can still be within the correct tolerances for size but become glazed (too smooth) which prevents good operation of the rings. Honing basically just roughens the surface slightly with a hand held spinning grinding stone that allows the rings to bed in again and seal better.

If the bores are not within the correct size range or have to much deep scoring then a rebore is needed. Here sufficient metal is removed (depending on the damage) by machine to return the bore to the correct roundness and finish but of course oversize rings and pistons will then be needed.

The decision of which to do depends on the damage seen or wear measured with special micrometers... 

[johny]

Additionally I hope a good machine shop would explain everything and show the readings if not the actual taking of the measurements....

[Iain T]

A honing machine! 

[johny]

Blimey thats a posh one! This is what I was thinking of:

[Iain T]

Johny, if yer gonna 'ave one 'ave a big one! 

Sunnen are quite a good machine but not for the DIY! 

Iain 

[johny]

And if thats for honing what does the rebore machine look like😳

[Iain T]

I think they specialise in honing but as its an American company in a big way with many products! 

Iain 

[Roger K]

It helps if you can get recommendations from locals for a decent machine shop.  I measure the bores myself with a bore mic, the crank journals with a mic and (before disassembly) the crank end-float with a dial gauge, but would still take the block, crank and pistons/rods along to the shop and ask them to assess it and advise on the best course of action.  They will recommend either a rebore to the first oversize if the bores are showing wear but no damage, or a larger oversize if there is damage that can be fixed by a more aggressive rebore.  You might, just might get only a hone recommended, but it would have to be pretty good for that as most machine shops won't want to risk their reputations, or a warranty claim, if the engine proves to be smoky etc. If they advise a rebore, they will tell you what size it needs (+0.010", +0.020", 0.030" (most common first rebore size for US V8s, not sure about the Triumph six), 0.040" and 0.060"), and will either offer to supply pistons or leave it to you to buy the appropriate oversize piston.  Any rebore cannot be done until the shop has the pistons, as different designs/makes will require different clearances in the machining.  The rebore finished size is dictated by the actual set of pistons to be used, in other words.

 If I'm having the block and crank done and a chemiclean of the coolant passages, I'll usually go the whole hog and have the rotating assembly balanced.  Obviously this will cost more, and they will need block, crank, rods, pistons, flywheel, clutch cover and crank damper.  If they balance these they should mark the clutch cover and flywheel for you so you can assemble correctly when you come to put the engine together.  Ideally the clutch will be zero balanced so you can fit a new one at a later date without upsetting the balance.

Hope that helps.  You can always measure bores, journals etc. yourself and make your own call.  Looking at your crank photos, I would expect that to need at least a polish, and I would want the bores measured for wear and ovality, if you don't have the kit yourself and don't know the history of the motor.

I stress - this is only my opinion.

[AidanT]

Thanks Roger that makes it pretty clear

It sounds to me as if I need to pass this over to a machine shop - There's one locally (12 miles away) which will mean getting it out of the garage into the moderns hatch somehow, and get them to lift it out. I will have a call with them when ready to see what they can do for me.

So on the basis then that they sort crank pistons/rings and head, what's left for me to do? Next few basic steps please 😊

I will of course continue to clean the block up as much as I can,  - probably a good idea I get the shop to dip the block as well though

Head will be sent off next week per the e-bay provider mentioned above

Thanks

 

Aidan

ps - I do have a basic micrometer screw gauge - so if there is anything I can measure let me know what and how

 

 

[Clive]

10 minutes ago, AidanT said:

Thanks Roger that makes it pretty clear

It sounds to me as if I need to pass this over to a machine shop - There's one locally (12 miles away) which will mean getting it out of the garage into the moderns hatch somehow, and get them to lift it out. I will have a call with them when ready to see what they can do for me.

So on the basis then that they sort crank pistons/rings and head, what's left for me to do? Next few basic steps please 😊

I will of course continue to clean the block up as much as I can,  - probably a good idea I get the shop to dip the block as well though

Head will be sent off next week per the e-bay provider mentioned above

Thanks

 

Aidan

ps - I do have a basic micrometer screw gauge - so if there is anything I can measure let me know what and how

 

 

You will need to put it together! Not always as simple as it sounds. 

[Roger K]

20 minutes ago, AidanT said:

Thanks Roger that makes it pretty clear

It sounds to me as if I need to pass this over to a machine shop - There's one locally (12 miles away) which will mean getting it out of the garage into the moderns hatch somehow, and get them to lift it out. I will have a call with them when ready to see what they can do for me.

So on the basis then that they sort crank pistons/rings and head, what's left for me to do? Next few basic steps please 😊

I will of course continue to clean the block up as much as I can,  - probably a good idea I get the shop to dip the block as well though

Head will be sent off next week per the e-bay provider mentioned above

Thanks

 

Aidan

ps - I do have a basic micrometer screw gauge - so if there is anything I can measure let me know what and how

 

 

I would just say that my post is what I would consider best practice.  As others have said, it's always possible that you can just clean up and carefully reassemble and it'll go for years - it all depends on what you want to end up with, how much you're prepared to pay and how much risk you are prepared to take!

Nothing wrong with screw micrometers - that's what mine are.  The old Moore & Wright ones with the ratchet screw are nice and reliable so long as they're calibrated.  You could try measuring the crank main and big end journals and see what you come up with.  Measure each one at least twice at 90°.  And yes, as Clive has said - putting it together will be what comes next!  At the very least you'll need a piston ring compressor, and if you've never fitted rings before you might consider buying some extra rings, shouldn't cost much.  Piston ring pliers are nice and make the job a bit easier, but the sky's the limt when it comes to buying tools.  That's why I never let my wife see me getting into the Snapon van...

[Iain T]

Aidan, do not forget to check or replace the beating heart of your engine...the oil pump! I had an 'experience' with my recently reconditioned engine because I didn't replace mine. I thought as the oil light never came on and the engine had done only a few thousand miles since the PO had totally rebuilt the car it was fine. Wrong the engine ran a mains in 500 miles! I don't know where my machine shop bought the pump but I think it was Moss. This pump has nearly 90psi at start up! 

Iain 

[Roger K]

Over the years, I have learnt the hard way (but not on Triumphs) that renewing or upgrading one element of an engine will often pass a little extra strain on to something else down the line.  On a worn engine, even doing a decent head job can increase the strain on the bottom end, leading to increased wear.  The phrase  'parts that wear together, play together' comes to mind.

[AidanT]

Thanks- I will add it to the shopping list

Full gasket set, New oil pump, new studs bolts and washers for head.

Anything else????

[Pete Lewis]

timing chain

 

Pete

[Roger K]

6 minutes ago, AidanT said:

Thanks- I will add it to the shopping list

Full gasket set, New oil pump, new studs bolts and washers for head.

Anything else????

Depends how far you want to go.  How old is the timing gear? What condition is it in?  Flywheel - does it need a skim?  Ring gear OK (they usually are)? Valve train (rockers, shaft etc.) - I doubt this will come with the reconditioned head?  Oil pump drive (if it's not part of the pump)?

It's years since I worked on a Triumph six-pot (correction - decades), but I do recall lots of warning lights around the crankshaft thrust washers.  Before you spend any money on anything, I would take the old crank bearings with you to the machine shop, if you take that route, and ask them to check the crank end float.  You'll need all the bearings so they can assemble the crank to take the measurement.  Given what you know about the engine it shouldn't be a problem, but it's a simple check.  If the thrust bearings have worn excessively the block might be damaged and that will cost.

[Iain T]

33 minutes ago, AidanT said:

Anything else????

Oil pressure relief spring, mine was very soft and may have been part of my problem. On a new 'tight' engine the oil needs good pressure the lubricate everything. 

[NonMember]

Roger likes to do things properly with little regard to cost.

Many Triumph owners are not in the fortunate position to be able to afford that.

To my eyes, the engine under discussion looks to be good enough for a DIY rebuild without involving a machine shop. If it wasn't an oil burner before you started, there's no reason to suspect it will be after a good clean and reassemble. Ditto for most other problems. Of course, as this engine is new to you, you don't know whether it burnt oil - although the photos of the pistons and valves before cleaning don't look like it did particularly. Perhaps I might just be a cheapskate but I'd suggest the money could be better spent elsewhere.

[Roger K]

2 minutes ago, NonMember said:

Roger likes to do things properly with little regard to cost.

Many Triumph owners are not in the fortunate position to be able to afford that.

To my eyes, the engine under discussion looks to be good enough for a DIY rebuild without involving a machine shop. If it wasn't an oil burner before you started, there's no reason to suspect it will be after a good clean and reassemble. Ditto for most other problems. Of course, as this engine is new to you, you don't know whether it burnt oil - although the photos of the pistons and valves before cleaning don't look like it did particularly. Perhaps I might just be a cheapskate but I'd suggest the money could be better spent elsewhere.

Perfectly valid response.  As I have said, my suggestions reflect my own personal approach only, although I might take issue with 'little regard to cost'!  I cost these things out very carefully.