TriumphTune TT10105N cam

[olr159w]

Can anyone advise whether the valve clearances on this cam are standard or are they something else?

thks

mark

[xvivalve]

Book advice is standard, though some informed wisdoms recommend halving the clearances on a performance cam...I'm sure they'll be along shortly to support their opinion...

[olr159w]

Thanks.

I had thought it was standard ie 18 thou inlet and exhaust so unless someone has convincing information to suggest something else that's the question answered.

I'm just surprised I can't find any reference to it in any paperwork or the Moss catalogue

rgds

[Mad Mart]

[olr159w]

Ah ha well there it is.

Some Moss or TT or Kent cams instruction that specifies pretty much half the std clearances

[soe8m]

Std gaps are a bit too wide.

Inlet I set somewhere inbetween 0,10-0,15 and outlet 0,15-0,20. You will have a nice quiet head this way. It isn't a pushrod, pedestal engine where multi parts can expand by heat between the camshaft and valve.

The lobe is directly or almost directly on the valve stem.

Jeroen.

[Carledo]

Std gaps are a bit too wide.

Inlet I set somewhere inbetween 0,10-0,15 and outlet 0,15-0,20. You will have a nice quiet head this way. It isn't a pushrod, pedestal engine where multi parts can expand by heat between the camshaft and valve.

The lobe is directly or almost directly on the valve stem.

Jeroen.

Let me just point out that the figures Jeroen has quoted above are metric (mm) for those who don't know the conversion factor it works out to 4-6 thou inlet and 6-8 thou exhaust.

Whilst I personally am not that brave, I don't have a problem with 10 thou all round and it does give a quieter running engine.

Steve

[olr159w]

Thanks for advice everyone.

Intending to re-install current cam (TT10105) on new head. 10 thou it is.

Over the life of production I had assumed the cylinder head remained unchanged. Is there a difference between early and late cylinder heads? Is that even a thing? What's the difference?

Thanks

[olr159w]

Anybody know whether the cylinder heads changed over the life of production?

thks

[soe8m]

Early heads have smaller holes for the studs and bolts. Uprated slightly thicker studs won't fit.
Skimming a head can be less forgiving then and does make the head not fit the engine properly anymore.

It can happen on an early head that with a fast road cam that has more lift you have valvespring binding. A worn head with thinner shims can go ok but fresh seats and valves you have to check carefully.

Power output wise there are no differences.

Jeroen

[olr159w]

Thanks for that.

So if I use the original late model head that has been skimmed 20 thou then essentially I don't need thicker shims?

Except if I do use the current head I will still use the thicker head gasket so doesn't that put me back where I started?

And is it the case then that if you wanted to convert an early head to a late head then you might simply take it to an engineering workshop and have the stud holes reamed out a tiny bit?

Is there any way to tell an early head from a late head when looking at it and without taking any stud hole bore diameter measurements?

Lastly, slightly different topic - timing chain tensioners. I've heard there are dud products in circulation. I'm thinking while its in bits I may as well replace. Where can I get a serviceable one?

thks

[xvivalve]

Later heads have a '2' embossed on the casting, both next to the AE logo on the inlet manifold face and also on the timing gear end. I did think there was a subtle difference on the valve spring pedestals as well, but my memory is hazy.

Thicker shims have little to do with the head having been skimmed, more with the camshaft having a reduced base circle diameter which moves the contact face further away from the valve top.

For timing chain tensioners, see this thread https://forum.triumphdolomite.co.uk/vie ... 5&start=45. Postage of both components to Australia would increase stated costs by £12

[olr159w]

Hi.

Interesting. I found a 2 on the timing gear end of mine but couldn't spot anywhere else. Mine's a 1980 car.

I take it there are no real drawbacks in using an early head? It does all sound a bit nebulous. On the other hand BL would only have made changes for a reason

I will be in the UK soon so if I got one of your tensioners mentioned in the other thread it could be sent to a UK address for me to pick it up in a few weeks time. They are GBP35 shipped in the UK?

I have no idea whether the current one is worn but it maybe doesn't hurt to have a spare available. Not the sort of thing you can wander down to the shops to buy here. Do the curved guides wear as well? The one I can see the end of looks OK if that's any measure of relative wear rates.

I see Rimmers say they are selling genuine MG Rover timing chain tensioners. But at the same time out of stock and due in Aug 26. They must have an intermittent supply of NOS

[xvivalve]

Yes, postage to a UK address would be easy and yes, £35; I only have 4 of the 'chassis' components currently, but will put your name on one.

Curved guides can wear, yes, but the reproduction ones are a bit 'soft' so a good used can often be better employed than a new one.

The other '2' is above the front most inlet port.

[olr159w]

I was looking on exhaust side. The 2 is there by the inlet port

Its annoying you can't see the degree of wear on the tensioner without taking the engine apart. The other guides look ok.

How would I place the order and pay you. I can transfer funds from UK bank.

And the early head design? No one is aware of any drawbacks?