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GT6 Engine .... What to check-out before refitting.

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Hi Nick,

It's strange that as I was bolting the head down I was thinking to myself what could I pop into the chambers that would measure the clearance between valves and piston crown.  I never thought of plasticine.  :biggrin:.

I also thought of taking the grinder to the domes and "reducing them" (machining them ) somewhat.. I resisted the temptation.

12.25 :1 is fairly high CR alright. I dont think pistons would stand up to that too long.


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  • 4 weeks later...

Ok. An update of sorts. I have located an engine which might suit. The engine is a runner and sounds sweet so at least that would help me get the car on the road while I consider other options. . It is out of a Mk2 Triumph 2000. The engine number is ML23346HEA. It is currently fitted to an automatic gearbox but I presume (hope) that I can fit my own flywheel and clutch.

As far as I can make out the engine prefix  ML2.. was fitted to the 2000 TC mk2. (May75 to May 77).... Would that be correct ??

What piston/head set-up would it have had ... (Domed with higher head ?) 

Are there any other issues (sump, engine mounts etc) that will effect fitting it into the GT6 ?





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7 minutes ago, UNFIT said:

What piston/head set-up would it have had ... (Domed with higher head ?) 

Yes.  They have a very boring cam fitted too.  It will have good torque low down but won't be very keen to pull past 4500.  It is in fact pretty much identical internal spec to a Mk3 GT6 engine.


8 minutes ago, UNFIT said:

Are there any other issues (sump, engine mounts etc) that will effect fitting it into the GT6 ?

You need to swap the engine backplate for the GT6 one.  The flywheel should be a straight swap for the flex plate. Ideally you would also swap the sump, otherwise you may well end up having to shim the engine mounts up to clear the rack.  T2000 has the engine mount brackets attached to the front plate.  You can either swap front-plates (fair bit of work) of take the grinder to them (bodge but effective).

If you get the carbs/manifold as well, something that late quite likely has SUs on a long manifold.  Quite nice from the performance angle (though limited by the cam as mentioned already).  However, you'll likely have problems getting the carbs to miss the bonnet as the saloon engine are fitted tipped 7º towards the manifold side so when mounted level as in the GT6 the manifold tips up by the same amount.  Also, the SUs are taller anyway.  So mind your lovely bonnet!!

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I thought Hs6 carbs and long manifold were only fitted to the 2500s and TC originally, could have been added to the engine at some point, maybe worth checking the stroke, you never know.

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The story with the engine is that it came fitted in a Stag that the chap bought. He has located a V8 engine for the Stag and so this engine is surplus to requirements. The engine was running well apparently and he sent me a video of it running before he took it out. I'm presuming it still has it's 2l internals. I did'nt even notice that the carbs were SU. I wouldnt tell the difference to be honest.

Problem is getting it down here at the moment due to lockdown.

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45 minutes ago, Mark said:

maybe worth checking the stroke, you never know.

True that. I know two or three people who have been surprised that way. One all the more so because he thought it was gutless even for a 2L :biggrin:. Went much better once he fitted a camshaft with the full complement of lobes.

20 hours ago, UNFIT said:

could I fit the 308778 that I discovered in my box of spare parts ? 

Yes. You’ll have to take the head off to do it though, and use new followers.

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Hmm, in my head, the fact that it’s come from a Stag makes me more inclined to think 2.5. Though actually there is no practical reason why it should be so.

It is true that with the youngest of these engines being about 43, the stamped engine number prefix is an unreliable indicator. There’s no telling what’s happened over that time!

One external indicator is the crank pulley damper size. 2.5 being bigger than 2L.  Not that obvious without both in view though.

Probably doesn’t matter much anyway. One of the lower spec 2.5s will give a relaxed drive in a GT6. If you want 2L then that head would go on the bottom end you already have.

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Cheers nick. If I have to change the sump then I suppose that would allow me the opportunity to check the stroke or maybe identify which crank is in it ???

With regard to rockers, I always thought that the cam followers should be numbered (or matched) with the pushrods when you stripped down an engine. The spare head and camshaft that came with my original engine had the pushrods numbered but the followers were loose in the box. How important is it to have each pushrod and follower matched and numbered ? 

Asking just in case I do decide to swop over the camshaft.

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Can I just add a note of caution with new followers? Some out there have the wrong radius where the pushrod sits it the follower meaning the pushrod is not sitting on the base circle on the end but rather on the edges of the "sphere" shape. Easily checked with some engineers blue.

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Good info thanks Jerry, not come across that. 
Also some out there (who should know better) sending out crowned followers. These are not obvious as the crown is quite subtle. Easy enough to check - just put two together face to face with a little engine oil. If they are flat they will almost stick together. If they are crowned they’ll rock a little. The crowned ones die quick.... don’t fit them.

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  • 3 weeks later...

I cleaned down the replacement engine and started to change a few things over. I replaced the front plate with the one from my old engine. I fitted a new timing chain. The sprockets looked ok so I went with them. I swapped over the distributor from my old engine as it had a cable drive for the rev counter. I removed the inlet manifold and the SU's and fitted the spare inlet and Strombergs that I had. I dismantled the carbs and gave them a good clean. I am waiting on a gasket kit to put them back together. I replaced the back plate (it was for an automatic box)  with the one from my own engine. I fitted new front and rear oil seals. With the sump off, I checked the main bearings and journals and the con rod bearings and couldnt see any sign of wear. No end float issues either that I could identify.

Perhaps you might help me with a few issues that I have encountered or considered:

1. Will I have problems with the distributor that I have now fitted to this engine. It came off the original ME87022HE engine which was fitted to the car when I bought it and it is a MK2 Triumph 2000 block. Although it was fitted with a Mk1 head if you remember. It is now fitted to a Mk 2 ML23346HEA engine.

2 I am slightly confused with the various water/coolant connections and also the crankcase breather etc. On my old engine, some of these were blanked off and I have looked for photos on line but Have yet to find one that answers all my queries. Here are a few photos and I have numbered the various connections that I am referring to. 



Outlet 1 goes back to the rad. 2 is connected to 3.  I think I am right so far.



Number 4 . Pipe from crankcase to inlet manifold 

Number 5. This steel pipe travels back under the manifold to the back of the engine.


Number 6 to connector on the heater matrix does it matter which one ?

Number 7 also to the heater matrix ?

Number 8 .... to where ?

Number 9 ... My old engine had this one blanked off.

Number 10 seems to be "sitting in no man's land" at present. the pipe from the water pump looks to be too long.


I presume number 11 here is the connection for the pipe back to the crankcase breather.


Well that's where I am at present. I have most of the engine bits reattached. Just need to clean up the gearbox now , fit the clutch, new spigot bearing and refit the gearbox.

Would there be any point in turning her over on the starter when I have the gearbox fitted. Maybe even do a compression test on it before fitting it to the car ??? 


Anything else you can think of ?? All suggestions much appreciated.

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Apologies for the belated comment 

You are correct on 1,2&3. Suggest getting a proper corner pipe for it though so it doesn’t just collapse. Also check there is a flow path through the manifold waterway, as blockage or severe restriction is common, but strongly avoid trying to undo the big banjo at the back end!

4 is the engine breather. Don’t connect it directly to 11 without a PCV (Smiths flying saucer type or modern equivalent) there are likely other breather connections on the carbs anyway.

5 this pipe comes in different forms according to model and that one looks to be big saloon, so ends in the wrong place. They are usually also either blocked, leaking or about to leak. Suggest buying a stainless steel replacement and the 1/2 olive needed to connect it at the water pump end.

6 left hand heater connection (inlet/hot side)

7 connects to rear end of 5 labelled 10

8 right hand heater connection (outlet/cool side)

9 Not used in GT6 application. Blank it off.

11 probably intended as a brake servo connection. Blank off if no servo or use for breather but only with a suitable PCV.

pics of mine below. Header tank is an extra and t’d into the 7-10 hose.



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