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

[AidanT]

After cleaning out my sump I have found the the two bolts at the front do not tighten. I guess some where in the engines history they have been over tightened 

So the questions are:

- Can I helicoil them or do I have to re-tap?

What size on either option?

Thanks

Aidan

[johny]

yes it sounds like the threads have stripped in the famous aluminium bridge piece that covers the front main bearing cap. It such a common problem that steel versions of the bridge are now produced but of course its a bit fiddly to fit them. I kept the original and without removing the sump drilled and retapped it to take metric allen head bolts (they had to be this type to fit in the channel in the sump but let me check the size).

It was relatively easy although does mean working from underneath the car and far more difficult is when the timing chain cover bolt that goes into the same bridge piece from the front strips...

[NonMember]

The two bolts at the front go into the aluminium filler piece that bolts in under the front main bearing. They're quite easy to strip.

Helicoiling is possible - easier if said aluminium bit is removed from the engine first. Of course, if you're doing that then you could just replace the worn out filler piece. Steel alternatives are available for improved resilience against gorilla hands.

[AidanT]

AHHHH!  Ok that's fine then, that will be replaced with the refurb, I've no need to worry

Thanks

[johny]

Out of interest: M10x1.5 and length 16mm

[AidanT]

Next 😁

Opinions on the valves on the  picture please

[johny]

Cant really say until they come out and get cleaned up. The critical bit is the sealing face on the other side of their heads and of course the seats. Certainly quite a build up on them so I think it hasnt been apart in a long time...

[JohnD]

They are valves.

What else did you wnat to know?

[AidanT]

10 minutes ago, JohnD said:

They are valves.

What else did you wnat to know?

Would you say it's the kind of state you'd expect or it's very tired??  Basically any thoughts on condition ? 

Someone said it was an oil burner!

Aidan 

[Clive]

6 minutes ago, AidanT said:

Would you say it's the kind of state you'd expect or it's very tired??  Basically any thoughts on condition ? 

Someone said it was an oil burner!

Aidan 

You are just looking at the faces of the valves, which tells you there are some deposits. You want to check how well each valve is sealing now, if the valve stem is worn, if teh guides are worn.

Worth getting unleaded inserts fitted while all apart, and 3 angle seats cut. 

 

Oil burning likely to be bores/rings, or badly worn guides.

[johny]

It might be a bit late now but unless youre going to do a full overhaul of an engine a compression test before strip down is a good way to get an idea of its condition.

Otherwise a machine shop can measure up everything to tell you if you have an oil burner and what needs doing to rectify it....

[AidanT]

So I know the valves need a re-grind, they don't hold spirit (didn't want to use petrol) 

Trying to get quotes doesn't seem as easy as I thought it would be!  Some are totally daft and obviously don't want the work. Some are just too far away and want to fit and run the engine in the car.

Mr Searle may be my only choice!

Aidan

 

[johny]

have you settled on new valve seats?

[JohnD]

That heavy ash deposit of the faces of the valves probably means it was an oil burner, which isn't really a problem if you are rebuilding the engine.    It's a pointer to look critically at the bores, for wear that would merit a rebore and oversize pistons, and for a lip at the top that might class with an ordinary top ring - but if you have a rebore that won't matter.

If the valves won't seal, then they need a regrind, possibly just by lapping them with grinding paste.  That is a job you can DiY   BUT, just that will remove any "lead memory'  lead pounded into the valve seat over the years that can proterct against erosion.    So steel inserts for the exhausts are essential.

What are you getting quotes for, or, rather, having difficulty getting quotes for?  Your local TSSC Area GRoup will know who to do to in your manor.

  How much work will you do yourself?   If you have never rebuilt an engine before, then these pages at Teglerizer, on rebuilding a Spitfire engine are very useful and the information is easily transferable:   https://www.teglerizer.com/triumphstuff/performancedata/III_whichengine.htm       

[AidanT]

29 minutes ago, johny said:

have you settled on new valve seats?

Yes  i think it would be daft not to convert to unleaded

What are you getting quotes for, or, rather, having difficulty getting quotes for?  Your local TSSC Area GRoup will know who to do to in your manor.

I got no response from some, and another was a crazy price nearly 4k!  

Original plan was to do it myself but no experience so reverting to getting it done

Thought I had a good starting point with a mk2 vitesse engine?

Aidan 

[ed.h]

On the stripped front sump fastening holes--if that bridge piece were aluminum, we probably wouldn't be having this conversation.  It is in fact a zinc alloy, much softer than most aluminum.  The fastener holes at the rear are in the aluminum rear seal housing, and have much less tendency to strip than those at the front.

And, yes, the stripped holes can be repaired. In fact many restorers will install thread inserts as a preventative measure:

http://bullfire.net/GT6/GT6-46/GT6-46.html

Ed

[AidanT]

Just to add that I would love to learn!  

Not that someone like this exists, but would love to learn how to rebuild the engine with someone, and would obviously pay for it. 

Guess it's just a pipe dream!

Aidan

[JohnD]

Since steel replacement bridge pieces are available, reapairing an old, stripped one seems unnecessary!

Can we persuade you to DiY, Aidan?     It is most satisfying to complete such a project, and it's really not even rocket science!    Read Calum's Tutorial (the link I posted) and have a think.    You will of course be able to get lots of encouragement and advice here, or from the local TSSC Group - who might even lened you some of the tools, like valve spring or piston ring compressors.

JOhn

[johny]

In my opinion hardened seats is not a given as its expensive and not guaranteed to be necessary. Its a complicated subject but many people successfully run their standard engines on unleaded as factors like annual mileage, driving style and conditions, fuel additives and engine set up can all affect the production of the dreaded valve seat recession. Also hardened seats of course wont stop the risk of the engine pinking on 95 octane fuel however it does seem that if you ever sell the vehicle the modifiction does add to its desirablity...  

[AidanT]

36 minutes ago, JohnD said:

Can we persuade you to DiY, Aidan?     It is most satisfying to complete such a project, and it's really not even rocket science!    Read Calum's Tutorial (the link I posted) and have a think. 

I'd love to, but could do with a step by step guide, preferably for the six pot. 

I do mean a step by step!  As in what tools to use (buy or borrow) to even how to clean up the head and block which all have circa 50 years of crap on and in them

I would like to have an unleaded head, just for convenience if nothing else

Aidan 

[Pete Lewis]

jump back to stripped bridge  threads  apart from gorilla hands  there are two bolt /setscrew lengths  many get a lon un where a short un should go and the bolt  bottoms out 

simplest repair is to tap oversize  even try similar sized M8 x125 as a coarser thread may just work

if you up to 3/8unf or 10mm  you need to open the sump hole to clear 

any engine machinist should be able to give the head a light skim and fit inserts relatively  cheaply  its not a mega bucks job 

Pete

[AidanT]

3 minutes ago, Pete Lewis said:

any engine machinist should be able to give the head a light skim and fit inserts relatively  cheaply  its not a mega bucks job 

Hi Pete

Cheapest quote for this was £450 inc vat 

 Didn't discuss shipping

Aidan 

 

[Pete Lewis]

as for tools very little , any half decent socket set , wire brush   can of brake cleaner/ degreaser

piston ring clamp , cartridge of something like loctite 574, feeler gauges , decent screwdrivers blade and poxi

pliers . scraper , box of rag and rolls of paper towel 

torque spanner ( look out at aldi/lidl) 

[Pete Lewis]

was that quote for recutting the 6  inlets 6 exhaust inserts and regrinding all  12  valves  ???? 

Pete

 

[Colin Lindsay]

8 minutes ago, AidanT said:

Hi Pete

Cheapest quote for this was £450 inc vat 

 Didn't discuss shipping

Aidan 

 

You can buy converted heads on eBay, £395 plus £16 postage; this includes collection of your old head as an exchange unit. 

https://www.ebay.co.uk/itm/TRIUMPH-2-LITRE-UNLEADED-HEAD-GT6-MK-1-2-VITESSE-MK1-2-EXCHANGE-RECON/113811613321?hash=item1a7fb36689:g:HFMAAOSwdX5c0Lno