Cylinder head work specification.

[Peter V W]

My TR5 cylinder head has done 95k.

Never had any work.

Bottom end rebuilt, 

Do not require a performance head.

what work do I require for modern fuel etc?

 

[Waldi]

Hi Peter,

first question is: why is it needed, the symptoms can affect the required work.

The opinions between forumnites will differ on hardened seats (or not) and it is also depending on how hard the car is driven.

Valve seat recession (VSR) is the issue.

I have a CP engine and when I rebuilt the engine I decided not to install inserts, because of the thin wall/bridge between inlet and outlet port on this head. Cracks could develop, as reported on this forum.

I dipped my head in fosforic acid, after removing the core plugs and valves, and then put it in an industrial washing machine. Now it was clean.

I replaced the guides (I opted for fosfor bronze with seals from Goodparts), the seats were cut (by a great German fellow TR-er), new valves (Chris Wittor) and standard double springs (Chris Wittor), and the head was skimmed, just enough to make it flat. New core plugs.

Finally painted the head with PU paint.

Think that’s it.

Waldi

[Peter V W]

Thanks Waldi,

Why, only because it’s on my “to do” list.

I have been using 97 unleaded with valvemaster plus for yeas, works fine.

Change gear about 3000 -3500 rpm, so no high revs.

Regards

Peter 

[Nigel Triumph]

I did pretty much as Waldi describes on my CP series TR6 more than 10 years ago, except I chose to have hardened exhaust valve seat inserts fitted.

My machine shop also refaced the existing valves. The old valve guides weren't replaced but were bored out and fitted with bronze inserts, reamed to exactly match the valve stems.

Remember to get the face of the cylinder head checked for flatness and have it lightly skimmed if necessary.

The head on my '6 has been fine since, running on 97 or 99 RON unleaded without additives. I would only expect problems from the valve seat inserts if they weren't fitted correctly, or perhaps in competition when the engine is run at high rpm almost continuously.

Nigel

[Peter V W]

Thanks Nigel.

[TriumphV8]

The seats especially on the outlet get little dimples.

Also the seats become wider.

 

At minimum there should be regrind and a refacing

to the correct width. Most of the outlet dimples should be gone.

Inlet should show a clean grey seat.

Also the valves and inlet runners and outlet should be

cleaned from coal.

 

I personally would swap the valve guides to those with rubber caps

and grind the inlet runners to match the chamber. Also some material

can be cut to make a smooth canal both inlet and outlet.

As this can go wrong I would give that to a specialist.

It is power for free and does no harm, so I like that!.

 

I do not use seat rings because I expect head crack between inlet and outlet.

If seats are envisaged I would only fit outlet rings.

 

 

 

Edited September 30, 2019 by TriumphV8

[Peter Cobbold]

On 9/27/2019 at 10:36 AM, Peter V W said:

Thanks Waldi,

Why, only because it’s on my “to do” list.

I have been using 97 unleaded with valvemaster plus for yeas, works fine.

Change gear about 3000 -3500 rpm, so no high revs.

Regards

Peter 

I would not be worried about valve seat recession   at those rpm.  The FBHVC tests to measure vsr were run at 5000 rpm at full throttle for many hours on a 1000 cc engine.  No-one on here has ever reported a case of VSR in a TR engine.  Peter

[Peter V W]

Thank you Andreas and Peter, plenty for me to think about.

[Kenrow]

The previous owner of my Tr 250 put in larger valves and seats, i went to redo my valves and my engine builder refused to move forward. I now have a big paper weight due to cracks between the valves.

[Jim F]

15+ years ago I had an engine rebuild and decided to 'improve' the head with new bronze valve guides.  Well I just had the head rebuilt, with stock guides, because 2 or 3 of the bronze alloy guides had loosened and moved.  No evidence that they's seized due to too little clearance, likely it happened because of differing thermal expansion coefficients over ~15 years.    Bottom line - I'd stick with stock guides unless there's a pressing reason to change.

Jim