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My 1974 TR6 has a cylinder head stamped 218225 and cast 312388.

A couple of people have said that I have the good head , I have checked and it has either come from a GT6 or a Triumph 2000.

Why are they considered better heads?

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I wonder if there is that difference.

If you enter the head with a grinder

you normally feel differences.

Here all I prepared have been similar

 

Some did jobs on the flow bench,

that is beyond my capabilities but

I have problems to believe the results.

Anyway Chris Wittor reports differencies on his website.

 

The main differences are the spacing between the inlets.

Aiming for PI this is a topic. Wider spacing is required.

Also the carb manifold for the wider spacing looks better for me.

 

The other difference is the exhaust valve size.

The smaller exhaust is preferred by me because

the core shift between combustion chamber and exhaust port

can be compensated better.

I prepared several heads with big exhaust valves and after

having all grinded to size there was some material missing

just under the valve seat area.

The smaller exhausts require more cutting and normally end with

a nice ported area aroung the valve seat.

Also here Wittor is different and claims to use the smaller valve for better flow.

 

Anyway I am a friend of the PI system giving some power over the twin carbs for free

without sacrificing low end torque like from wilder cam that has to be collected back by a

lot of tricks like compression, head work and proper AFR ratio and ignition timing.

 

The compression ratio and size and shape of the combustion chamber can be

grinded and milled to suit with any of the heads. The US versiond require to

mill off quite a bit more, thats the difference.

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My 1974 TR6 has a cylinder head stamped 218225 and cast 312388.

A couple of people have said that I have the good head , I have checked and it has either come from a GT6 or a Triumph 2000.

Why are they considered better heads?

+1 for John. I do not know where your info came from? But my old SAH chart shows that your numbers refer to MK2 PI MG5000 to MG82077 or TR6 CR type, exhaust valve size 32.0 m/m?

 

Bruce.

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Like this?

I took this to mean Triumph 2000 saloon

 

520873 218225 312388 3.400 Mk2 PI MG50001 to MG82077 Flat 32.0 8.125 Yes No

 

Two people from companies who work on injected Triumphs told me it was the good head.

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I've got a pdf open with the info that the head was fitted to these.

 

TRIUMPH SIX CYLINDER ENGINES Mk2 CYLINDER head applications chart

Part No. (bare)Head No. stampedCasting No. raisedHeight nominal (inches)ApplicationsPiston typeExhaust valve (mm)
Pushrod length (inches)EGR humpRear water slot

 

520819 218225 312388 3.4 Mk2 2000 from ME50001 to ME86355 -86508. Mk2 GT6 Dome 32 8.125 Yes No

 

So am now really confused.

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Yes Triumph 2000 mk2 and GT6 mk2....Chris witor chart, some differences to tr6 true head.

Cheers,

Conrad.

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Thank you, at least I'm not going mad. :)

The car goes really well and I am not planning to change anything, just interested.

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Yes Triumph 2000 mk2 and GT6 mk2....Chris witor chart, some differences to tr6 true head.

Cheers,

Conrad.

My TR6 I have owned since new it is a 1973 CR type and has the original head on it. Guess what Listers numbers are exactly the same as mine! and as shown in the SAH list from 40 years ago, as originally stated in my thread #4. That means it is a genuine TR6 type head. If you want to know what the major differences are to the early TR6 type are. Its all to do with thickness of cast iron in certain sections to prevent warping and cracking between valve seats. Lastly, it was to be used with the modified Coopers/Payen ( same company) cylinder head gasket, which was re-enforced on the fire rings and the block counter bored around the bores, to improve compression sealing.

 

Bruce.

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My 1970 CP has the same head as Bruce and Lister. I've always assumed the head was changed because of a problem in the past. So if it is a CR head on a CP am I missing out on anything?

 

Cheers

 

Dave

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No. Head may have been changed in the past but no practical difference. I suspect that when people say the "good" head, they mean one with 32mm exhaust valves as many later cars had the 219015 head with smaller, 30mm exhaust valves. This was changed to try and reduce the incidence of cracking between the valves (usually cyl 1 or 6) some consider it affects performance.

 

Nick

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