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

[Roger K]

21 hours ago, johny said:

Out of interest: M10x1.5 and length 16mm

I haven't got into my engine yet, that comes early next year - but before I do, are you sure on that bolt size?  I'm surprised that a sixties UK block would have metric fasteners.

In this instance, unless I was about to do an engine strip-down I would helicoil the threads in situ.  Easy enough, and will end up stronger than the original.  Why did Triumph use an aluminium piece here originally rather than steel, I wonder?

[NonMember]

I don't think johny was talking about the original fitment but rather what he had re-drilled and tapped his to because of stripped threads. The original were 5/16" UNF

[Roger K]

Just now, NonMember said:

I don't think johny was talking about the original fitment but rather what he had re-drilled and tapped his to because of stripped threads. The original were 5/16" UNF

Ah, OK, that makes sense.  Personally I'd helicoil back to 5/16 UNF, as I'd soon forget the metric change had been made.  That said, it's not a spanner issue as they're panhead screws, so I guess it really doesn't make much difference.

[Pete Lewis]

alloy block was easier to make and if you use the right length setscrews and the low torque spec its not a problem 

till 50 years on and we invented mix and match with a gorilla thrown in for good measure 

and the ability to rebuild anything without a book of words to complement  the  skllls  

well its  quite foggy 

Pete

[Colin Lindsay]

1 hour ago, Roger K said:

Ah, OK, that makes sense.  Personally I'd helicoil back to 5/16 UNF, as I'd soon forget the metric change had been made.  That said, it's not a spanner issue as they're panhead screws, so I guess it really doesn't make much difference.

Panhead screws for the alloy sealing block into the engine block, but bolts from sump to sealing block. Is it the engine block to sealing block that's leaking, or the sump / alloy sealing block seal?

[AidanT]

6 hours ago, AidanT said:

Nearly sorted out the head refurb, thanks Colin / Johny

They did say to get a Payen gasket, now I know there's been chatter on the new ones not being good, so can anyone tell me where to go to get nos, and which one? Thought it was GEG179  but now I'm not sure

OR Am I completely wrong on this?

 

Thanks 

Aidan 

https://m.facebook.com/groups/116689651680167/permalink/3748877951794634/

This is the article  not sure if it's true - your thoughts??

[johny]

2 hours ago, Colin Lindsay said:

Panhead screws for the alloy sealing block into the engine block, but bolts from sump to sealing block. Is it the engine block to sealing block that's leaking, or the sump / alloy sealing block seal?

Dont think theres any leak Colin just not able to tighten the sump bolts. I liked the M10 - 1.5 bolts I used because  their thread is courser than the original UNF which I think is too fine for alloy even with helicoils....

[AidanT]

On 07/12/2020 at 10:50, Pete Lewis said:

you need to clean the top of the bore , there will be carbon on the unswept top few mm  if theres a wear step you can get your finger nail in it needs new rings with a step top ring..

Hi Pete 

How much can be bored out before you need to change pistons? And in terms of new rings what price would I be looking at?

I found an engineering firm locally who could do a re-bore for under 200 quid

Aidan

[Pete Lewis]

any boring will need new sized pistons as you are changing the bore diameter 

you can hone /glaze bust and re use youre  orig pistons with new rings of the orig size 

you do need a light hone to glaze bust the old polished bore or the new rings will never bed in well

no idea on price  ,  its down to search the reliables or piston manufactute sites 

[AidanT]

On 07/12/2020 at 10:50, Pete Lewis said:

Aidan  can you photo the bearing shell  in the cap you removed  ??

Here are the two internal shell caps

 

[AidanT]

Head has had first stage clean ups - all but no 6 now have no lip to the touch and no 6 u can't get a finger nail in. Pistons are a little pitted on top

Also noticed that at least some of the pistons held the brake cleaner in the chamber

 

 

[johny]

I would say looking pretty good so far. Bearing shells arent very worn and have probably been replaced at some time (check that they are standard size...), what do the mains look like? 

[Roger K]

The bore in the photo looks to be scored to me, unless it's an artefact.

Have you checked the crank journals with a mic?  The shells don't look too bad, but it's worth checking properly.  And yes, see what the mains look like.

I like the 'side-mount' on the engine stand - nice idea, means you can actually do the flywheel and clutch on the stand for once!  Not seen that before....

 

[Pete Lewis]

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 

see  if it disappears with a rub of fine oliy wet dry 

john wont like the idea of wet dry but thats all youre going to have right now 

pete

[AidanT]

Roger  I think that's a cleaner smudge - I have put my fingers all around and the only possible issue I can feel is a ring around the top of no 6 (the top pic)

So more questions and please remember I'm a novice at this

What do I need to do to remove the pump? Taken the feed tube off but not made any difference to the pump itself

 

 

[AidanT]

4 minutes 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]

More pics

 

 

[Roger K]

Sorry, may have missed this - how many miles has it done?  Something to consider is that it is possible for the bores in a block that look good to be worn oval.  On the power stroke, as the piston is pushed down it exerts sideways pressure on the block, at right angles to the crank axis.  Speaking entirely personally, I would either measure the bores or get a machine shop to do it.  I'd have a chemiclean done too - I'm always amazed at the difference between a home scraper job and what the machine shop can get out.

That's very much a personal opinion and I appreciate that you may be wanting to spend no more than is absolutely necessary - I'd rather button it all up knowing that I shouldn't have to touch it again for years.  

There is a school of thought that suggests that if you're not going for machining work, it might be better just to clean and reassemble as the parts will have worn together over the years.  Depends really on what the compression figures were, what the oil pressure was and whether or not it routinely ran hot.

[NonMember]

7 minutes ago, Roger K said:

 I'd have a chemiclean done too - I'm always amazed at the difference between a home scraper job and what the machine shop can get out.

- I'd rather button it all up knowing that I shouldn't have to touch it again for years.  

When I rebuilt my GT6 engine, because of terminal failure of the timing chain hardened shells and consequent wrecking of the oil pump and all the bearings, I only gave the bores a good hand clean with brake cleaner or equivalent. I do appreciate that this was a bodge done as a quick fix for the short term. However, that engine has since done five Round Britains, several 12-car rallies, holidays and all the other driving that car has seen in the 27 years since that rebuild. It has not needed any work at all.

 

23 minutes ago, AidanT said:

What do I need to do to remove the pump? Taken the feed tube off but not made any difference to the pump itself

Probably just a bit more brute force. The pump is only fixed (or even fully located) by the three long bolts that hold the pickup tube and cover. However, they do get fairly well stuck over the years. Try twisting it, it may break the sticky seal. You can pull the rotors out first, although you may need to push the shaft from the other end (down the dizzy hole with the drive gear removed)

[AidanT]

Hi Roger

Engine purchased second hand, was told the engine was good but no idea on history. John Bonnet knows the guy I purchased from and said he was a good source and reliable. Mike Papworth also knows him

Tried a compression test but failed, however I know now the head leaks so now not surprised 

Please come back on the oil pump, that's my next removal 

Thx

 

Aidan

[AidanT]

5 minutes ago, NonMember said:

Probably just a bit more brute force. The pump is only fixed (or even fully located) by the three long bolts that hold the pickup tube and cover. However, they do get fairly well stuck over the years. Try twisting it, it may break the sticky seal. You can pull the rotors out first, although you may need to push the shaft from the other end (down the dizzy hole with the drive gear removed)

Thanks - will try - quick tap with a hammer maybe??

Sorry can't call you non-member

Aidan 

[Pete Lewis]

Aidan  NM is a Rob   if that helps  

Pete

[Roger K]

13 minutes ago, NonMember said:

When I rebuilt my GT6 engine, because of terminal failure of the timing chain hardened shells and consequent wrecking of the oil pump and all the bearings, I only gave the bores a good hand clean with brake cleaner or equivalent. I do appreciate that this was a bodge done as a quick fix for the short term. However, that engine has since done five Round Britains, several 12-car rallies, holidays and all the other driving that car has seen in the 27 years since that rebuild. It has not needed any work at all.

OK, that's good!  There are so many variables - if you know the engine's history, have driven it before the strip-down etc. it is possible to make these calls.  Fifteen years ago I ran a big end bearing in my Mustang's 393 on the Estoril race track during a touring run, so it came home on a trailer.  I dropped the sump and removed the relevant cap, to find the shell down to the copper but no marks on the crank.  The engine was a new Ford Motorsport crate motor, which had only done 3,000 miles since installation.  It turns out Detroit had told me the wrong sump capacity (crate motors have to be shipped empty, and come on a pallet with a new, unmarked dipstick taped to the pallet.  Sump was an aftermarket Canton unit - suffice to say Ford tech said it was a 7 litre sump, when it was actually a 10-litre, which I found out the hard way....).  As I knew the history, I measured the journals with a micrometer and polished the crank in situ, fitted a new set of big-end shells (mains not possible with the engine in), and 45,000 miles later all is still fine.

Most of this is down to luck, I'd say.

[Colin Lindsay]

25 minutes ago, AidanT said:

Thanks - will try - quick tap with a hammer maybe??

Rob's right - if you've got the long bolts removed there's nothing holding the pump in place other than love for the block... just pull, tap gently with soft wood or the like, don't blatter the bejeezus out of it with a metal hammer. It'll drop off easily enough.

[AidanT]

Thanks 

Rubber hammer tap and it's out

There are comments above re no 6, so I pulled the piston. Here are the pics

Aidan