Lead free fuel.

[jefferdp]

Hi,

I have always added fuel additive to my stag as I am not sure that it has hardened value seats.

Then while working on one of the bikes, I am restoring at present, it came to me that I have never had to use additive on any of my bikes, which also have aluminium heads, because they are able to run on un-leaded just because they were fitted with aluminium heads. Therefore the valve seats had to be hard.

So am i correct in believing that the Stag heads have to have hardened valve seats because the heads are made aluminium? So adding a additive is a waste of time?

Your thoughts on this please?

Regards Dean.

[bonnietiler750]

By now they would be case hardened anyway
Triumph always used high density Iron inserts on Aluminium heads,i would be very surprised if you got any recession after this time
Regards
Brian

[Will]

Hi Dean I have thought the same jap bikes since mid seventies have been ok on unleaded

[Guest]

For once and for all.
There is no such thing as unleaded stuff for Triumphs.

The only truly "unleaded" valve is a stellited exhaust valve.
Inlet & exhaust valves are soft and in any case are usually 2 piece with the head friction welded to a dissimilar metal stem.

If you look at the vast majority of "unleaded" conversions it's bollox.
A new exhaust seat is pressed into the head, & it's very hard (or at least moderately hard).
This is supposed to be the key piece that prevents seat recession.
The valve however is cheap, and almost invariably NOT stellited.- it's quite soft again with a 2 piece welded construction.

If you look at this valve eg. a modern OPEL, after 50 000 miles it's pitted to heck and the seat all rounded out and distorted.
However most modern cars are designed to be thrown away after 4-5 years, which is usually about 50k.
By the time the engine really needs a rebuild, the car is taken down the yard and crushed.

On any old fashioned alloy head engine such as the Stag, the exhaust valves are going to be soft,and so are the seats.
It's this compatibility of hardness that allows the thing to resist unleaded fuels.
I have checked after market valves, eg County and they are SOFT.
They have NOT been stellited, like 80% of the cheap stuff fitted in production engines.
T

To give you an example, doing things better, a Jaguar valve is stellite treated, and the stellite ground back to create an ultra hard seat. You will find this sort of nymonic material 21-4N going back to the 1950s, as Jaguars have alloy heads going back decades. The acid test is with a magnet.
Proper valve head material is not magnetic, but even then the stainless so called "Triumph race valves" eg. MOSS/toilet-tune are NOT unleaded and haven't even been stellited - TO-SAVE-MONEY.
The untreated stainless steel stems are not even nitrided, making them wear badly!

Fyi,-
The seat in a Jaguar head is not usually very hard, certainly not like the very hard ones that can be fitted nowadays, but I've seen them do 200 000 miles + with no wear at all.
The usual problem with the Jaguars are they rot so badly, the car is down the yard before anything in the head is remotely close to worn.
The AJ6 was so astonishingly reliable, the yards I know used to weigh in whole crates of 50 at a time for scrap alloy.
It was impossible to sell them, because they never ever went wrong.
Nothing changed.
The XK8 has a reputation for rotting so catastrophically, the car and the alloy subframes under it have died in under 7-8 years.
It's the ultimate "kleenex car"!

Simple situation is, STAG V8, Dolomite 16V, TR7 doesn't need "unleaded" seats, the compatibility of the metals is good enough for everyday use.
For a competition type engine, in any case you change the valves for better ones, so the issue doesn't occur.

[DJT]

The Stag heads will accept unleaded without modification, as long as the exhaust valves are of the correct spec. Original ones will have the number 155524VL etched into the stem and these are fine. Some cheap aftermarket exhaust valves were available in the '90's and these would burn out. Quality valves since then would be made for unleaded spec. I would use unleaded fuel and stop worrying about it.

I speak from driving over 90,000 miles in 2 Stags, and stripping the heads on both after at least 30,000 miles on supermarket unleaded fuel (no additives). On neither engine was there any sign of valve recession, nor did I have to adjust the valve clearances in that time. The only problem I have encountered was two exhaust valves burnt out after 25,000 miles in the head that was reconditioned by one of the largest Triumph spares suppliers in 1992. Unsuitable valves were used.

There are plenty of other Stag owners who have driven stellar miles purely on unleaded without problems.

[Jeff]

For once and for all.
There is no such thing as unleaded stuff for Triumphs.

The only truly "unleaded" valve is a stellited exhaust valve.
Inlet & exhaust valves are soft and in any case are usually 2 piece with the head friction welded to a dissimilar metal stem.

If you look at the vast majority of "unleaded" conversions it's bollox.
A new exhaust seat is pressed into the head, & it's very hard (or at least moderately hard).
This is supposed to be the key piece that prevents seat recession.
The valve however is cheap, and almost invariably NOT stellited.- it's quite soft again with a 2 piece welded construction.

If you look at this valve eg. a modern OPEL, after 50 000 miles it's pitted to heck and the seat all rounded out and distorted.
However most modern cars are designed to be thrown away after 4-5 years, which is usually about 50k.
By the time the engine really needs a rebuild, the car is taken down the yard and crushed.

On any old fashioned alloy head engine such as the Stag, the exhaust valves are going to be soft,and so are the seats.
It's this compatibility of hardness that allows the thing to resist unleaded fuels.
I have checked after market valves, eg County and they are SOFT.
They have NOT been stellited, like 80% of the cheap stuff fitted in production engines.
T

To give you an example, doing things better, a Jaguar valve is stellite treated, and the stellite ground back to create an ultra hard seat. You will find this sort of nymonic material 21-4N going back to the 1950s, as Jaguars have alloy heads going back decades. The acid test is with a magnet.
Proper valve head material is not magnetic, but even then the stainless so called "Triumph race valves" eg. MOSS/toilet-tune are NOT unleaded and haven't even been stellited - TO-SAVE-MONEY.
The untreated stainless steel stems are not even nitrided, making them wear badly!

Fyi,-
The seat in a Jaguar head is not usually very hard, certainly not like the very hard ones that can be fitted nowadays, but I've seen them do 200 000 miles + with no wear at all.
The usual problem with the Jaguars are they rot so badly, the car is down the yard before anything in the head is remotely close to worn.
The AJ6 was so astonishingly reliable, the yards I know used to weigh in whole crates of 50 at a time for scrap alloy.
It was impossible to sell them, because they never ever went wrong.
Nothing changed.
The XK8 has a reputation for rotting so catastrophically, the car and the alloy subframes under it have died in under 7-8 years.
It's the ultimate "kleenex car"!

Simple situation is, STAG V8, Dolomite 16V, TR7 doesn't need "unleaded" seats, the compatibility of the metals is good enough for everyday use.
For a competition type engine, in any case you change the valves for better ones, so the issue doesn't occur.

[Guest]

on supermarket unleaded fuel (no additives).

This is a total misnomer.
Most "supermarket fuel" comes from exactly the same tanks as all the other stuff the tankers collect from the very small number of refineries now left operating in the UK.
By definition, petrol has to have additives in it or it the specific cocktail wouldn't work.

Most people don't know UK fuel is distributed through a network of pipelines constructed in the 2nd world war.
The UK is/was a net exporter of refined petrol, but a net importer of aviation fuel & diesel.

http://www.telegraph.co.uk/business/2016/05/27/uk-reliance-on-oil-product-imports-hits-32-year-high/

The top exports of the United Kingdom are Gold ($41.6B), Cars ($40.8B), Packaged Medicaments ($19.9B), Gas Turbines ($14.7B) and Refined Petroleum ($13.2B, Its top imports are Cars ($49.9B), Packaged Medicaments ($21B), Refined Petroleum ($20.2B), Crude Petroleum ($17.3B) and Vehicle Parts ($15B).

[jefferdp]

Gent's

Thank you all for your replies, brilliant I will now use un-leaded without any additives from now on knowing that I should be ok.

Regards Dean,

[DJT]

This is a total misnomer.
Most "supermarket fuel" comes from exactly the same tanks as all the other stuff the tankers collect from the very small number of refineries now left operating in the UK.
By definition, petrol has to have additives in it or it the specific cocktail wouldn't work.

Most people don't know UK fuel is distributed through a network of pipelines constructed in the 2nd world war.
The UK is/was a net exporter of refined petrol, but a net importer of aviation fuel & diesel.
http://www.telegraph.co.uk/business/...-32-year-high/

Having worked in the oil sector (exploration, production, transport and distribution) from 1971 until I retired in 2013, I am aware that forecourt petrol is pretty much the same stuff no matter what label it comes under. However, many consumers believe that 'supermarket' fuel is inferior to the major brands.

[Jeff]

Having worked in the oil sector (exploration, production, transport and distribution) from 1971 until I retired in 1913, I am aware that forecourt petrol is pretty much the same stuff no matter what label it comes under. However, many consumers believe that 'supermarket' fuel is inferior to the major brands.

.

I was told that supermarket fuel does not return good MPG.

[DJT]

.

Oops! Now edited. Put it down to breathing in too many octanes..........

[Markvh]

Isn't it the percentage content of ethanol in petrol we have to worry about?
I use Total standard unleaded which I believe doesn't contain ethanol (In my part of the East Midlands anyway). I also believe that the Super unleaded petrols doesn't contain ethanol, but it's soooo expensive.

[davidf]

I have previously posted this information

According to the Leyland Parts Catalogue for the Triumph Stag, the exhaust valve is 148093. It is supposed to be hard enough for un-leaded as it works with a stellite valve seat which is inserted into the aluminium head. However the UK was not using un-leaded at the time the Stag was designed.

Back in 1997, there was information in the SOC magazine about alternative valves 155524 which were reputed to be for US spec TR7's (where un-leaded was already in use). These are supposed to be harder. It was reported that these had been used in later Stags although it is not documented.

I built my engine in 1984 from a new short engine and new head assemblies (UKC1416/7). I found that these were fitted with exhaust valves 155524 (which is consistent with the reports of being used in later Stags).

I notice that Rimmers quote 155524 for exhaust valves for Stag, TR7 and Dolomite. They don't list 148093.

You can find the part number at the top of the stem of the valve.

I don't think anyone has reported valve erosion with the original valves so it is a matter of choice if you have original valves.

I would be interested if 'down_the_plug_hole' could comment.

[Guest]

I was told that supermarket fuel does not return good MPG.

This is hearsay.
Being as 85% of the fuel put in your car produces no torque at the flywheel, but emerges as waste heat, I want to know how one can possibly detect variations in combustion of +/- 5% in the remaining 15%.

It's NOT possible,- you would have to vary the calorific values and measure them.
The only drop in calorific energy possible is by increasing fractions of alcohol by 20-30%, as alcohol, particularly methanol has a lower value per kg.
That combustion figure can only take place at full throttle at the points below.

(For a gasoline engine, maximum efficiency usually happens slightly before maximum load when at low rpm)

Anything below that and a gasoline engine with partial cylinder filling is running compression ratios as low as 3-5:1

I would suggest the +10 bio mix is using mostly ethanol, which probably does lower this value by a small amount.

This is the typical efficiency curve of a production engine



I would imagine the Stag V8 is average.

I did a back to back test roundly condemned as unscientific etc, using a TR6 pi on the rolling road. (late CR model).
I changed the fuel out between each run (which took a few hours to do)....emptied tank and all.

It was all done at my cost.
I used this expensive stuff rumoured to give more power (Shell optimax 97-98)and all the usual caveats about the impossibility of running the TR6 on 95 Octane without retarding the ignition etc.

I did the first test with Optimax, then Total 95 (people love to slag that off!), and a variety of shell 95, BP etc.

Try as I might, the power output within the capability of detecting any difference were absolutely identical.
NO difference in torque on any sample from 1500-5000rpm. (within 2ftlb, full load).

Notice the bottom line on the graph is how the car came in needing a good tune up to begin with!
That was 8ftlb down across the entire range.

TR6_fuel_cr_test1b.jpg

Finally, a test we did with a modified engine back to back against a STD TR5 against various weather temps.
The power under full load is at the rear wheels.

The engine proved to be exceptionally sensitive to atmospheric temp variations, which is something I always had suspected.
It dropped 10bhp at the wheels for every 10C rise in air temperature.

Notice how the "perfect" TR5 makes 99bhp at the wheels, and the test mule was making as much at the wheels as the original engine was supposed to make at the flywheel but never did...

Again, we used 95 octane and 98 octane in various tests, the engine only pinks louder at 3000rpm using 95 octane, but made the same peak power.