Un-Leaded or don't Worry About It.

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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Baller
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Un-Leaded or don't Worry About It.

#1 Post by Baller » Fri Aug 04, 2017 6:23 pm

Probably this topic has come up before but is it worth the expense having the head converted to run on unleaded petrol. How well do they run on our petrol we have today ? I guess they are not running high compressions so I can't imagine them having trouble pinking but you guys that are on the road with these cars may say different. One factor I guess is the amount of mileage being done , any body got any Ideas on the cost of the conversion , I welcome any opinions on this subject :D

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Re: Un-Leaded or don't Worry About It.

#2 Post by johnnydog » Fri Aug 04, 2017 8:38 pm

Cars that ran on leaded fuel for many years developed 'lead memory' so for a reasonable period of time (years) the protection that lead afforded was retained. But it is now 17 years on. Many of the Register members I know use just ordinary unleaded with no detrimental effect. Personally, I use a lead substitute additive - I did quite a lot of reasearch in the lead (no pun intended!) up to the abolition of leaded for the best additive. The FBHVC also did a lot of tests, and one of the best additives that came out of it was the manganese based Millers VSP. There were also sodium and phosphorous, but they did not fair as well as the manganese in tests.
I have used Millers since 2000 with all my Triumphs, with no problems whatsoever. Admittedly, when you could still get leaded fuel after the introduction of unleaded, the Triumphs always seemed to 'fly' with a tankful of the 'good stuff', but with unleaded and Millers additive, I never get any pinking, no reducing valve clearances, although I don't do a great mileage every year admittedly. The other benefit of Millers is that it also increases the octane content (RON) by upto 2 points, making standard unleaded up from 95 to approximately 97. I prefer using super unleaded, which gets the octane count up to a healthier 99 to 101 depending on which fuel you use. Super unleaded is also a lot 'cleaner' fuel apparently and my cars run better off it.
Millers additives have now progressed on to the VSPe, which has been developed to help combat the very harmful effects of the ethanol content in today fuels which is very corrosive for older cars and the various metal components in their fuel systems, which has been addressed with modern cars. It also helps with the sometimes long periods of inactivity with our cars, by reducing the 'stale' effect with petrol that is a few months old. Modern fuel deteriorates very quickly, over a short period of only several months.
As to getting the head done, personally I wouldn't bother. If the head is being removed for other reasons, and the cost isn't prohibitive for you, then perhaps consider it, but I personally really don't think there is any real need.
I also like the Millers 20/50 Classic Performance oil for our cars because of the higher zinc content which is lacking in some other supposedly classic 20/50 oils.
And no, I don't work for Millers - I just like their products!
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1970 Mk2 2000 in Valencia Blue
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1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: Un-Leaded or don't Worry About It.

#3 Post by Charles H » Sat Aug 05, 2017 12:08 pm

Agree with John. I too did the research and have used Millers additives together with Shell VPower since 2000 with no valve seat recession and done high mileages at high revs (especially on the rally car). I am now using the Millers VSPe multishot. Great stuff!
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Re: Un-Leaded or don't Worry About It.

#4 Post by Baller » Sun Aug 06, 2017 6:34 pm

Thanks for your thoughts guys , much appreciated , I think I'm quite likely to make sure the valves are lapped in nicely with no leakage and the guides are all good new stem seals and leave it at that ,I will make a note of the additives been suggested to.

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Re: Un-Leaded or don't Worry About It.

#5 Post by tony » Mon Aug 07, 2017 5:42 am

Wonder if you lap the valves in too much you will destroy the lead memory ?
Just a thought.
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Re: Un-Leaded or don't Worry About It.

#6 Post by Clifford Pope » Mon Aug 07, 2017 8:02 am

Does lead memory actually exist? Everyone assumes it does, but I've done a quick google and can't find any scientific analysis of what precisely the mechanism is supposed to be.
Could it just be a combination of several factors;

valve erosion is somewhat exaggerated
some cars may not be as bad as others at eroding anyway
most people with classic cars drive quite gently
most classic cars do very small annual mileages ?

And is the memory supposed to be contained in the actual metal to metal contact between the valve and the seating, or is it in the built-up deposits in the combustion chamber, mitigating some of the harmful side effects of the combustion process, like a kind of catalyst?
One would surely be lost on grinding-in the valves, the other if the head were de-coked?

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Re: Un-Leaded or don't Worry About It.

#7 Post by David Withers » Tue Aug 08, 2017 3:25 pm

In an effort to answer Clifford's very valid questions, I've copied below an article that I submitted to SIXappeal several years ago (1998/2000?). John's comments help bring it up to date, and in particular I go along with his warning about 'lead memory' reducing over the period of time since leaded fuel went out.

Running our Triumphs on Unleaded Petrol - © David Withers

This ‘question and answer’ session may be helpful in dispelling some of the confusion that seems to abound about running our cars on unleaded petrol. The following information is factual to the best of my knowledge but no guarantees can be given as I have no way of knowing your particular vehicle or how it is driven.

What was the purpose of the lead in leaded petrol?
Lead, more correctly tetra-ethyl lead, was first introduced into petrol in the 1920s as an octane booster but it was also found to have lubricating properties that reduced valve seat wear. From that time on, the design of iron-head engines took into account the protection afforded by leaded petrol, which meant that the iron didn’t need to be highly wear-resistant and steel inserts were rarely needed.

Unfortunately much of the world later decided that lead was a bad thing and so its permitted levels in petrol were gradually reduced until eventually it was virtually outlawed. This led to concerns about exhaust valve seat recession in engines such as the Triumph 2000 and its variants which have cast iron cylinder heads and are not fitted with valve seat inserts.

So what exactly is valve recession?
When an engine is run hard and at high speeds, the exhaust valve can get hot enough to pull flecks of iron from the seat in the cylinder head. These flecks then get hammered onto the mating face of the valve and become very hard. As the valve rotates (which it is intended to do so as to even out any wear, also to keep the sealing faces clean) the hard flecks that have become virtually welded to it chew away at the seat. The loss of metal from the seat causes the valve to sink resulting in the working clearance between the valve stem tip and its associated rocker lever being lost.

Some valve/rocker (‘tappet’) clearance is necessary to ensure that the closing valve is pulled firmly onto its seat so as to give good metal-to-metal contact and thus allow heat to transfer to the cooling system. If the valve doesn’t close firmly the valve head overheats and starts to burn away which, with the associated valve seat recession, is likely to lead to very severe damage.

What can I do to avoid valve seat recession?
Steel valve seat inserts can be fitted to the head, perhaps together with special valve guides to reduce valve stem/guide wear and scuffing. Chris Witor’s advertisements carry details of what he can offer for our big Triumphs. There are many other firms that can do this work, but it is essential to choose one who knows what they are doing because a loose seat is just as much of a problem as a recessed seat. Normally only the exhaust valve seats will require inserts.

Alternatively, there are several petrol additives and so-called fuel catalysts on the market that claim to compensate for the loss of lead and thus allow unleaded petrol to be used. Unfortunately, advertisements for the catalysts very cleverly hide the fact that they are totally ineffective, and several additives are also of dubious merit. The Federation of British Historic Vehicle Clubs (FBHVC), in conjunction with the Motor Industry Research Association (MIRA) and Rover Group, set up a sophisticated test programme in 1998/9 to sort out the good from the bad.

Additive and catalyst marketers were invited to submit samples for testing, however the cost of the tests couldn’t be fully borne by the FBHVC so they asked the product marketers to provide £5000 apiece towards the cost, in return for which their test results would not be published without express permission. In reality, this meant that Joe Public would be kept in the dark about any additives or catalysts that did badly in the tests – and some did very badly! What this means to you and me is that we can rely only on the products that have been approved by the FBHVC and should totally avoid all others.

A list of additives could get out-of-date quite quickly but the approved ones can be easily identified because they will carry the FBHVC crest of approval on the container. Don’t waste your time looking for the crest on any in-line or in-tank catalysts because none of these achieved approval. Manufacturers of these gismos tread a very fine line with their clever use of words and at least one has already been prosecuted for making false claims.

Is there any alternative?
Yes, gentle driving. If you restrict continuous engine speeds to no more than 3000 rev/min and don’t overload the engine, you will be most unlikely to have any problems in running on unleaded petrol.

Load in itself is not harmful, however labouring up hills or heavy towing can take the valves over the critical temperature and introduce the risk of valve seat recession. Occasional excursions over 3000 rev/min, such as when accelerating through the gears, will do no harm so long as the engine is not over-hot, noting that it is the temperature of the valves that rules here, not the oil or water temperature.

3000 rev/min as a maximum continuous engine speed is a generalisation that covers most makes of old cars. Our Triumphs appear to be able to exceed that engine speed without problems, however sustained speeds above 3500 rev/min ought to be avoided with any recession-prone engine running on unleaded petrol. Note that an automatic car may in fact run cooler than a manual that is being laboured in overdrive-top. Remember, it is speed-with-load that is the most damaging.

What should be borne in mind is that the higher the engine speed, the more heat is produced and the relatively shorter time the valve is in contact with the seat so as to transfer heat to the cooling system. The valve seat angle, contact width, spring pressure, camshaft design, cooling system efficiency and much else will affect susceptibility to recession and its rate of progress, however overheating of the exhaust valves by high engine speed and/or load is the root cause.

What about Lead Memory?
Engines with a long history of using leaded petrol have an advantage in that the valve heads and seats will have been coated with lead compounds, commonly known as 'lead memory', which should continue to act as a solid film lubricant for many thousands of miles. Long use will also have work-hardened the valve and seat mating faces and this will help against recession.

Leaded petrol would also have lubricated the valve stem/guide interface and any ‘lead memory’ that has been left behind will help avoid scuffing. I don’t think there’s much likelihood of scuffing in standard unmodified engines; however if you need 100% assurance you may want to have special valve guides fitted or use an approved petrol additive.

What else do I need to be wary of?
When using unleaded petrol you may have to retard the ignition timing to avoid ‘pinking’ (detonation) but the need will vary from engine to engine. The Triumph 2500S engine in my own car has needed no change from the original ignition timing of 10 degrees BTDC and it has now completed about 10,000 uneventful miles on unleaded petrol, often being driven quite hard. This can be explained by the fact that its 219016 cylinder head was designed with lower grade petrol in mind, also the compression ratio is only 8.5:1 compared with, for example, the 2500PI at 9.5:1.

Retarding the timing increases running temperature and reduces efficiency, therefore it is something to be avoided if possible. Using one of the additives that raises the petrol’s octane rating might overcome pinking without any need to alter the timing. Remember that pinking can be very damaging so please don’t ignore it!

How can I check that recession is not taking place?
Start off with accurately set valve clearances (‘tappet settings’) and check these any time you are concerned that recession may be starting. If the clearances haven’t reduced, there is unlikely to be any valve recession.

Be aware, however, that any sudden recession is likely to take place when you are on a long journey, perhaps bombing down a motorway, i.e. you will break down far from home, not in the local supermarket car park, because it is a combination of heat and speed that does the damage. If you want to drive your Triumph at more than 3500 rev/min for extended periods, or expect the engine to run hot, then perhaps you ought to be using one of the FBHVC-approved additives (at every fill) or fitting an upgraded cylinder head.

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Re: Un-Leaded or don't Worry About It.

#8 Post by johnnydog » Tue Aug 08, 2017 9:45 pm

I remember reading this article back then with great interest especially following my own research when all the rumourmongers out there were predicting doom and gloom after the abolition of leaded fuel.
It still is an interesting read and very factual in my opinion, although since 2000 I have not encountered anything like the number of our engines predicted to subsequently need head work through the use of 95 unleaded. This I presume is down to the majority of owners not using their cars as frequently as they used to, the effects not causing the degree of wear predicted, and possibly treating their cars with more respect due to their age (this can refer to the cars AND their owners!), and also some using additives!
I attended a seminar in Sheffield late in 1999, at which I became convinced on Manganese based products for use in additives. I understand that there was some initial concern in the USA about the effects of manganese on the environment, but it was established that the amount used in fuel additives had no particular ill effects, and is therefore still available today.
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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Re: Un-Leaded or don't Worry About It.

#9 Post by Charles H » Wed Aug 09, 2017 3:12 pm

Good to read that again. I did have an old 2000 run through my hands some 15 years ago which was scrapped. It had horrendous valve seat recession because it had been used very hard with no additive. The exhaust valves had nearly disappeared into the head. Should have taken photos! Mangenese based VSPe for me and I use it every tank!
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Re: Un-Leaded or don't Worry About It.

#10 Post by Dazzer » Mon Aug 14, 2017 3:47 pm

I had hardened valve seats fitted and I also had the distributor curve retarded more for the cam than the valve seats. The compression is also now in the 10:1 region. Don't use an additive but use 97 octane where available but also runs quite happily on 95 standard which is the only fuel available in many smaller rural garages. head was on for 45k on the first engine (driven hard and rallying) same head going onto the second block with just a lap and off we go again.

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