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Triumph TR6 - VAlve seats replacement with liquid N2 dipping


Few time ago I saw on TV at "How is it made" at Ferrari Co., they insert valve seats inserts after deep frozen them in liquid nitrogen. The used a wood holder to fit seat in head. I know that Ferrari are some kind of wheelbarrow in comparaison with a TR6, but: Has someone ever tried that?

As I want to replace my TR6's seat's inserts with unleaded type.

And up to now each time I had inserts installed by a "PRO" for a MGB, Volvo, Toyota, I faced problems as the became loose after a while...
May be it could be a solution

Jean G.
J. G. Catford

Although I have not done that it is a pretty common method to get a good interference fit without pressing the parts together. Sometimes the "receiving" piece is heated as well.
Brent B

We install bushings using that method on a regular basis. What you need to take into account is how much interference you need to have between the two bits and size the receiving bore accordingly to match up with the standard bushing (or in this case valve seat). You then determine what the "treated" (chilled or heated) diameters need to be for the install. This is done by using the thermal expansion/contraction coefficients of the materials involved, the chill method (freezer, solvent with dry ice bath, liquid nitrogen, etc) and or heat used along with the operating temperature.

All in all, it's not hard but it must be precise and depending on diameters and conditions, it is not uncommon to get in to .xxxx" type numbers with very small tolerance ranges.

Jean, why don't you buy a Ferrari and try it out on that and let us know.
I hadn't heard that the inserts had a loosening problem in the past.

Mr Kelly,

Ask Don Elliot, he confirmed my fears about inserts coming loose in TR6 also. And, he is my reference on TR6.


Jean G.
J. G. Catford

Jean, is your car your daily?

No, here in CDN far north...

It is suitable only during summer, it is coming after my 3 Jags and Pontiac and Merkur. But this winter it is TR6 engine's overhaul turn...

Jean G.
J. G. Catford

Unless you plan on spending a lot of money on the head ,wisdom's been to not worry about the unleaded seals.

Well Don,

I want to do things to last for a while. And I never touch that 89,0000 miles engine except once to have a burnt valve replaced, the "specialist" replaced also some valve guides. The results was 2 exhaust valves stuck in guides in a 5 min. run. After having solved that problem, the engine was never the same with strange noise at valve level and I was unable valve lash stable for some valves. I forgot the car for a while and following advices I got here I decided to replace cam + follower. I bought a new Performance BP2 270 from BPNW plus silicon-bronze guides and I am ready..

Jean G.

P.S. a Toyota Supra swap will be done with HVDA kit but the problem is to find a decent gearbox. I am tired to have engine at 4,000 RPM on highway, furthermore the car has a Stebro free-flow exhaust.
J. G. Catford


Thanks for your input..

Jean G.
J. G. Catford

This thread was discussed between 11/01/2011 and 12/01/2011

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