Valve guide info

[fastblatt]

Here we are again. I’m after some more info from the knowledgeable amongst us. I’m currently in the process of replacing the valve guides on my ‘74 (m) 2000. I measured the distance from the head face to the tips of the valve guide then knocked them out. Ordered new ones from the brothers assuming they would be correct however ther is a problem. I now see that Haynes and this very website list the guides as 2.72 in long inlet and exhaust and Haynes says that they should be 0.75 from the top of the head to the end of the guide.
The brothers and mr witor only seem to have guides at 2.251 (ex) and 2.062 (in) which Haynes indicate are for the 2500. I haven’t been able to find any “standard “ length guides listed anywhere. Also in my measuring I seem to have made a mistake or missed something as the old exhaust guides were about 0.625 from the top of the head to the guide end but this makes the tip in the chamber recessed in the guide hole, I know this may be difficult to understand. Can anyone give me so help, info, pointers?
Many thanks in advance
Mark

[Mike Stevens]

Hi Mark,

Mk2 heads are the same for 2000/2500 with the exception of the chamber depth. This is a bit of a generalisation but as far as the guides go, I'm pretty sure it's true. The standard part numbers are the same for early 2000 and PI (58923 for inlet, 2.0625" long and 111869 for exhaust, 2.25" long). You say that your guides are the same length for inlet and exhaust which suggests you have a Mk1 head with 119622 guides for inlet and exhaust?

The 0.75" rings a bell with me and is what I remembered from when I last changed guides. I used a press and made up a 0.75" collar to define the guide depth when fitting the new ones.

Cheers,
Mike.

[Alec]

Hello Mark,

from one of my workshop manuals (Standard Triumph, blue plastic covered so is an early manual) it list the following, :-

2000, inlet length 2.72 and exhaust 2.72, 0.750" above the cylinder head (These I believe are for the early cylinder head which is quite different to the later one), 2.5 P.I. inlet length 2.0625, exhaust length 2.25, 0.63" above cylinder head.

I would say the latter dimensions would apply to your 74 car.

Alec

[fastblatt]

Thanks Mike, and Alex the dimension sticking out is helpful. So mine will be a later head (I would have thought) so the guides are right ( or they would be if the inlets weren’t 0.030 shorter than quoted by the supplier) The guides I bought are the same as what came out (two different lengths) I was only going by Haynes and the info on here, but the exhaust ones now I come to refit seem too short. I feel I should be seeing the tip of the guide protruding a small amount inside the chamber but at the correct set depth the guide its recessed in the hole. Whats annoying too is the day I went to do the job was the prefect conditions, lovely hot sunny day got the head really warm and the guides chilling in the freezer
Mark

[Alec]

Hello Mark,
personally I have never botherd heating/cooling them to fit. Bearing in mind the coefficient of thermal expansion is tiny that forty or fity degrees makes little difference. Iron is about 12 x10-6 per degree c so you are only gaining a fraction of a thou. Does no harm of course except they may stick to your fingers:-)

Alec

[Mike Stevens]

By 'early' head I assume you mean Mk1, and 'later' Mk2? That would seem to fit. Also the guide height above the head being different between Mk1 and Mk2, but I got the figure wrong for the Mk2. The theory still holds though. The main difference between Mk1 and Mk2 is that the Mk2 fixings to the block are all on top of the head, on the Mk1, the manifold side fixings are under the manifold ports, so much lower down. Mk1 also has distinct pushrod 'tubes'.

In the Mk2, I think the exhaust guides do sit slightly below the casting in the port. I can probably find one to photograph if you like?

Cheers,
Mike.

[fastblatt]

If you can find a photo Mike that would be great thanks
Mark

[Mike Stevens]

I think I have a Mk2 head in the garage. I'll try to extract it and take a suitable photo.

Cheers,
Mike.

[Alec]

Hello Mike,

I don't think the head I'm thinking of was ever fitted to the MK 2. It's that long since I've owned a 2000 MK 1 my memory is hazy, but I seem to remember that the ignition side had very short studs with the nuts below plug level and used 3/8" diameter studs as opposed to the 7/16" of the later head?
Alec

[Mike Stevens]

Hi Alec,

You're right, except that the 'short' side is on the manifold side. As you say, smaller studs too and (when I had a Mk1) it was prone to blowing head gaskets.

Cheers,
Mike.