Fuel & its effects on your engine

The summary of the report is published below, together with the MIRA report on fuel additives

SUMMARY

• Due to economic forces, it is inevitable that leaded petrol will not be freely available within the next five years or before.

• Aftermarket fuel additives need to be carefully matched to the fuel to which they are to be added.

• The quality of the construction of Jaguar engines, even including the cast iron units from the pre-war period, is such that, if carefully maintained and driven, catastrophic engine failure should NOT occur.

• The use of unleaded fuel will induce higher running temperatures.

• Unleaded fuel, generally being of lower octane rating, will render the car more susceptible to detonation or pinking from sources not directly attributable to the fuel, like oil dilution of the petrol, localised overheating, etc.

• The American experience is such that the often talked about valve seat recession will not be a problem with Jaguar engines.

• Maintaining a relatively low engine cruising speed is important.

RECOMMENDATIONS

Don't panic! - the process of valve seat recession or erosion of the cylinder head material, even if it were to occur, would take place over many tens of thousands of miles. With the low mileage that many of these cars are subjected to, any potential problems would probably not occur for 5 to 10 years assuming the engine is in a reasonably good condition to start with.

If it ain't broke, don't fix it! - if you have no reason to remove the cylinder head or carry out an overhaul at this stage in time then the introduction of lead free fuel is not reason enough in itself to go to the expense of overhauling your engine. It must be stressed however, that the valve clearances need to be checked and re-set if necessary. Ideally 0.001in to 0.002in wider than the nominal 0.004in or 0.006in setting recommended for the earlier engines. This may make the valve gear slightly noisier but will reward the owner with a more reliable engine.

Any damage that may be caused due to running on unleaded fuel would be gradual and, if the engine is maintained correctly and the car driven sympathetically, then as the engine degrades, a loss in performance would be noted before it would actually break down and a plan could subsequently be drawn up to rebuild it at a convenient time.

If an engine is to be rebuilt then certainly the fitment of lead free valves is to be recommended.

On pre 1975 engines, if they are to be rebuilt. then the fitment of lead free valve seats is certainly worth further investigation at that stage. The decision would be taken dependent upon the condition of the existing seats and cylinder head material (eg, is the aluminium eroded from previous detonation or water ingress from head gasket failure?) and also the hardness of the seats which can be determined by standard procedures. Adjust the mixture so that the engine is running slightly richer particularly around the 2,500 to 3,000 rpm mark. This can be achieved by carefully selecting different grade needles and/or jets or possibly (with care) filing a needle locally at some point down its length. This would need to be carried out by someone experienced in the modification of such needles.

• Ensure that the cooling system is correctly assembled and is functioning efficiently.

• Post-1975 engines all had valve seats fitted to take into account the use of unleaded petrol and would not necessarily require replacement.

• However. if anyone is in any doubt as to the ability of their engine to withstand the use of unleaded fuel then they should change to unleaded valves or seats when they wish.

• Maintain your car correctly and base the level of service on time and NOT on mileage.

• Enjoy driving your classic car and don't allow yourselves to be browbeaten off the road by those faceless powers that be.

FUEL ADDITIVES - The MIRA Tests

Now that the Motor Industry Research Association have completed their tests originated by the Federation of British Historic Vehicle Clubs, as you will have probably read elsewhere, the results came out clearly in favour of only four additives. These were:-

Millers VSP-Plus

Red Line Lead Substitute

Sunarblend 12/Zero Lead 2000

Valvemaster

There seems little point in re-defining the actual tests or the results suffice to say that these were the only four to pass the apparently stringent tests carried out by MIRA.

On the basis of these tests any of the four additives should be perfectly OK within your Jaguar engine if you need them at all. We will again refer back to David Marks's extensive appraisal of the situation last year formalised into a separate brochure still available from the Club for just £1.25.

In essence his report stated that the majority of Jaguar engines are quite capable of running on unleaded fuel PROVIDING the engine and the cooling system are in excellent working order and operating efficiently. This meant that the general state of the engine should be good and that the cooling system is operating correctly and within adequate parameters as the use of unleaded fuel will make the engine run hotter anyway.

You should also take into consideration the fact that many of you will not be using your Jaguars as everyday transport. many perhaps with less than 3,000 miles per year and only in the summer months. Therefore you have to ask yourself, do I have a problem anyway'? It would, at worst, take several years for any problem with valve seat recession to show up on such a small mileage basis so you could save money now by not considering any major work to your engine or in fact using additives at all. If and when your engine does need major work You could then consider having the valves done which Would work out cheaper in the long run.

If you want the "feel good" factor of an additive anyway then there certainly appears to be no harm in using one of these products, but remember, this is an on-going cost on top Of fuel you buy. Additives are not a once only "fix" and you will have to keep on buying them.

So, let's look at the four choices and where you can buy them. It should, however. be considered that once you have chosen your path and bought an additive, you should stick to it!

Do not attempt to mix these products as they use different metallic trace elements that may or may not be totally compatible with each other or with your fuel!

MILLERS VSP-PLUS - This was the only product approved which also contains an octane booster. This could be of considerable benefit for the Jaguar engines as they are used to running on high-octane fuel and it may mean you don't necessarily have to have the timing retarded.

The Millers product comes in 250ml bottles, which is enough to add to 40 litres of petrol and costs £3.20. This works out at about 8p. per litre additional cost to your fuel. The product won't be available until early June. If you have any difficulty in obtaining it, then try Millers direct on 01484 713201.

SUPERBLEND 12 / ZERO LEAD 2000 - The first of the three not to contain an octane booster so with this and the others you may need to retard the timing slightly.

This one comes in a handy plastic bottle with a measuring cap to ensure you put exactly the right amount into the fuel tank. A standard 500ml pack contains enough additive to treat 150 litres of fuel and costs in the region of £5.99 including VAT. I think this works out at about 4p. per litre additional cost.

Again if you have any problems in sourcing Superblend then telephone 0116 291 1700.

VALVEMASTER - This also isn't available at the time of writing but will be supplied in 250 ml bottles or in larger bulk amounts. Price is estimated at around £5 per bottle, which should work out at something in the region of 3p-4p per litre additional cost. For more information telephone 01908 273606

REDLINE LEAD SUBSTITUTE - This appears the most expensive for it costs £13.50 but this is apparently enough to treat 450 litres of fuel. So actually comes out at around the cheapest at an additional cost of 3p per litre. No knowledge yet on availability but you can contact Redline: 01476 861195.

LRP
Then, of course, we should not forget the possibility of LRP. Lead Replacement Petrol. This is, in effect 97 octane unleaded petrol with one of the protection additives already in the fuel. Apparently there are no standards yet established for this and we don't know how widespread its availability will be but that then is another alternative to the use of additives.

A Further Complication
Burlen Fuel Systems inform us that there is another potential problem to using unleaded fuel in engines not originally built to take it. This is the effect of the more "aggressive" nature of unleaded fuel on nitrile based "O" rings, diaphragms, seals and even rubber pipework in the fuel systems of many classic cars.

Apparently, the US market addressed this problem years ago and now Burlen have worked closely with them and SU and Zenith branded products, proving the suitability of various alternatives for use with unleaded fuel in the UK.

They can now supply all that is needed and for more information and advice it is best to contact them direct at Burlen Fuel Systems on 01722 412500.