Valves

[Glenn]

I’m pretty new to triumph tr6 and in the market to buy one. I’ve seen one advertised and the owner has done 3000 miles in 10 years. He can’t tell me if the valves have been changed to run on unleaded but he said he is running it unleaded. He isn’t mechanically minded at all. Is there any way of telling? 

[RobH]

Welcome to the forum Glenn.

Apart from taking the head off I don't think there is really any way of telling whether hardened exhaust valve-seat  inserts have been fitted ( It isn't the valves themselves) .  Perhaps an endoscope might show something......?

However, the consensus of opinion - at least as far as TRs are concerned - seems to be that this really isn't an issue for a road car which isn't thrashed continuously at high revs and which does a limited annual mileage. There seem to be  plenty of unconverted TRs running around quite happily on unleaded, with or without the use of one of the 'magic potions'.   

 

[Waldi]

Welcome Glenn,

during my rebuilt, after reading the differing opinions/aspects on here, I decided to not install hardened seats. Have not driven the car after the rebuilt, so no miles to back this up.

Waldi

[Mark69]

I was given the same advise by the engineer who machined my engine parts, said if it was a weekend ,occasional car limited mileage not to bother.

like Waldi haven’t driven mine either( apart from up and down driveway.)

Mark

[Nigel Triumph]

Welcome Glenn.

While it would be nice to know if the hardened exhaust valve seats for unleaded have been fitted to your prospective purchase, they aren't essential.

These TR engines (4 and 6 cylinder versions) will cover tens of thousands of miles on unleaded without serious trouble. No doubt others here will corroborate. It's worth converting only if/when the cylinder head needs to be removed for some other reason.

The exception would be if the engine is to be worked hard at high revs, as in competition. For normal road use, simply fill up with unleaded and enjoy driving!

Nigel

[Mike C]

TR6 valve seat recession due to unleaded petrol, one of the great fears of 1999, has gone the way of the Y2K bug. For most of us it never eventuated.

Back then I used to sweat on every issue of Practical Classics , with their latest FBHVC test results.  At the time the TR expert that ported and polished my head was long retired and I didn't want anyone to touch it.

[Allan Jezzard]

Hi Glenn and welcome.

I agree with all the posts on this one. When leaded petrol was “withdrawn”, engineers thought their time had come. TR owners rushed to have new valve seats fitted. I though I’d wait until other head work was necessary and have it all done together.

Since then, I have done an average of 5k miles a year without having any head work done or without using the incredibly expensive leaded fuel - if you could even get it. Furthermore, I use no additive and the head has not even been removed in the 30 years I have owned the car.

Just my experience!

Allan 

[Mark69]

Great to read all the reviews, I did wonder at the time when my engine was in bits if I had made the right decision in not having it done.
I can sleep easier now.

Mark

[Waldi]

I think someone said that cutting the valve seats would remove the protective layer, making the seats more vulnerable to VSR (valve seat recession). I simply could not imagine that the protective Pb-layer would remain that long after leaded fuel was no longer available, so I just cutted the valve seats, no inserts (well, Andreas did and I admired his skills looking how he did it).

Waldi

[harlequin]

5 hours ago, Waldi said:

I think someone said that cutting the valve seats would remove the protective layer, making the seats more vulnerable to VSR (valve seat recession). I simply could not imagine that the protective Pb-layer would remain that long after leaded fuel was no longer available, so I just cutted the valve seats, no inserts (well, Andreas did and I admired his skills looking how he did it).

Waldi

Hi Waldi

Like many I have not had inserts fitted thinking I will do it when it needs it, now twenty years later it still going and I am to tight to buy expensive fuel.

My theory as to why it has lasted so well for so long is that the seats over the many miles have work hardened rather the having a protective layer, least ways that's what I am hoping.

George 

[Waldi]

Hi George
I think cast steel cannot work-harden like 300series SS does (not completely sure), but I can imagine the exhaust gasses are “hammered” in the matrix, a bit like shot peening. 
Others will know I hope.

Cheers,

Waldi

[Yarm 783]

I agree with all of the relies, it is also worth using good quality higher octane fuel, such as Shell VPower or such like, it’s a bit more expensive but easier on the valves.

[foster461]

I rebuilt my TR6 engine at just over 60k miles and did not fit hardened valve seats. No sign of any recession. Car has now done over 100k miles. Normally run it on Shell vpro, E10 unleaded.

Stan

[Andy Moltu]

Is V power any easier on the valves? Like regular unleaded it is really formulated for modern cars and I would doubt fuel suppliers are much concerned about the relatively small amount of sales to classics without hardened valve seats this long after leaded fuel was killed off.

It has a higher octane rating so can cope with higher compression ratios and ignition advance before pinking but I've never come across any convincing evidence that exhaust valve seat recession is less likely to occur with it.

Tetra-ethyl lead was the ingredient that good old leaded petrol used in days gone by as an octane booster and was found to reduce valve seat recession on cast iron heads that didn't have hardened valve seats. I wasn't greatly convinced that "lead memory" was a real thing, it's just that on the average classic the loads on the valve seats meant that losing the protective effect of lead didn't induce the rapid burning away of the seats. Certainly faster than with leaded fuel but not fast enough to justify removing the head just to fit inserts.  Wear may be faster in hot engines that have been tuned to rev higher and with uprated valve springs that might accelerate seat wear.

Worth doing when you have your engine apart certainly.

[foster461]

30 minutes ago, Andy Moltu said:

Is V power any easier on the valves? Like regular unleaded it is really formulated for modern cars and I would doubt fuel suppliers are much concerned about the relatively small amount of sales to classics without hardened valve seats this long after leaded fuel was killed off.

It has a higher octane rating so can cope with higher compression ratios and ignition advance before pinking but I've never come across any convincing evidence that exhaust valve seat recession is less likely to occur with it.

Tetra-ethyl lead was the ingredient that good old leaded petrol used in days gone by as an octane booster and was found to reduce valve seat recession on cast iron heads that didn't have hardened valve seats. I wasn't greatly convinced that "lead memory" was a real thing, it's just that on the average classic the loads on the valve seats meant that losing the protective effect of lead didn't induce the rapid burning away of the seats. Certainly faster than with leaded fuel but not fast enough to justify removing the head just to fit inserts.  Wear may be faster in hot engines that have been tuned to rev higher and with uprated valve springs that might accelerate seat wear.

Worth doing when you have your engine apart certainly.

I use the Shell gas because of the 10:1 compression ratio, I only mentioned it for completeness. Oddly my TR3A had severe valve seat recession and I had hardened seats fitted.

Stan

[stuart]

16 hours ago, foster461 said:

I use the Shell gas because of the 10:1 compression ratio, I only mentioned it for completeness. Oddly my TR3A had severe valve seat recession and I had hardened seats fitted.

Stan

Probably been run on Ethyl from new in Florida.

Stuart.

[RogerH]

17 hours ago, Andy Moltu said:

 

Tetra-ethyl lead was the ingredient that good old leaded petrol used in days gone by as an octane booster and was found to reduce valve seat recession on cast iron heads that didn't have hardened valve seats. I wasn't greatly convinced that "lead memory" was a real thing, it's just that on the average classic the loads on the valve seats meant that losing the protective effect of lead didn't induce the rapid burning away of the seats. Certainly faster than with leaded fuel but not fast enough to justify removing the head just to fit inserts. 

Hi Andy,

Valve seat recession is caused by a process called 'Galling'

This is where two materials come into contact, usually under high pressure, transfer metal from one to the other.  This is a real process - physics. 

The way to stop this is to make the surface dirty. This way you simply transfer the dirt about.

There are a good number of materials that would do the job but It was found that a good medium was Tetra-Ethyl Lead. as this also reduced detonation (pinking)

So after 1000's of miles the two faces become contaminated with Lead and so stop the galling.

Modern valves and better head material have helped reduce recession in the absence of TEL

But if you put your foot down it will wear.

 

Rogerr

[Andy Moltu]

My point was that the lead probably doesn't stick around for all that long to offer any long term protection once leaded fuel wasn't used any more.  Some would argue that the protection from valve seat recession was indirect in that leaded fuel burned cooler/with a slower flame front than the early unleaded fuels.

Nor did I suggest that valve seat recession isn't a real thing: it is just a bit slower than the doom mongers predicted in our cars (as many are not driven very hard) so it's not worth stripping down a good engine to do an unleaded conversion until you have either a good reason to suspect that the seats have recessed/burned or the engine is out or apart to do other works on it.

The cost of lead alternatives probably isn't worthwhile, just save the money to spend on having hardened seats/valves when the time comes. I think someone was even selling tetrethyl lead to add to the tank but I'd be really cautios about handling that without the right protection as it enters the body quite easily through the skin.