Ford Club Serbia

Why Can’t Older Engines Use Unleaded Fuel?

By far the biggest problem arising from using unleaded fuel on older engines is a condition known as valve seat recession (VSR). Without the protective lead coating (previously provided by leaded fuel) on the exhaust valve seats, the intense heat (650°C) and hammering effect of the valves opening and closing, causes iron deposits from the valve seat to become micro-welded to the valve edge. Left unchecked, this continual tearing away of metal particles will result in the exhaust valve digging a deeper and deeper hole for itself into the cylinder head. Eventually, and often within only a few thousand miles, the engine will breakdown completely and it will require an expensive overhaul. To combat this problem, modern petrol engines have special hardened valve seats which can withstand this harsh environment.

Firstly, all Capri engines, except the turbo equipped models, will run on unleaded petrol provided every fourth tankful is 4 star leaded. This is possible due to a phenomenon called 'lead memory'. Lead from the 4 star actually stays within the combustion chamber and on the valve seat for some time. If unleaded is to be used, the second problem of pinking must be overcome, and this is done by retarding the ignition timing...

If you own a 3 litre Capri, you could have hardened valve seats fitted to your existing cylinder heads (as you could with any Capri engine), and this would also solve the problem, apart from necessary timing adjustment that will be required. It has been reported, however, that under certain circumstances some valve seat inserts have fallen out into the combustion chamber while the engine has been running, which resulted in engine destruction!

There does seem to be a very easy, relatively cheap and simple solution to this problem, in the form of a Catalyst that is simply added to the fuel tank. There are two companies marketing similar products, both of which have been running advertisements in the car magazines. One is called 'Broquet Fuel catalyst', and is marketed by David Lock and Associates, and the other is called 'The Fuel Cat', and is marketed by a company of the same name.

They both claim to allow a 'Lead only' engine to run continuously on unleaded petrol without the risk of engine damage and without having to retard the ignition timing. Sounds too good to be true, I hear you say. I too was filled with scepticism, so I contacted both companies to obtain further information.

I wrote to David Lock first to gain information on 'Broquet'. David then rang me and we spoke at great length about what 'Broquet' is and how it does what he claims. It would appear that it was developed during the Second World War to allow Hurricane aircraft, on loan to the Russians, to run on the very poor quality fuel they had at the time, and this it did very successfully. More recently, it has been used by the Civil Service Motoring Association since 1989, and collectively their members have covered in excess of 200 million miles using Broquet with no reports of any engine damage from any of their 10,000 members.

Basically, it consists of a mesh bag filled with predominantly tin pellets, which is simply dropped into the fuel tank. This causes a catalytic reaction which causes it to change the properties of the fuel, resulting in much more efficient burning, and this in turn means that the combustion temperature is significantly lowered to below a safe level for 'Lead only' engines to operate. This more efficient burning also gives improved fuel economy, more power and less carbon build up in the cylinders, so a cleaner engine. Broquet also offer an 'Engine Damage Warranty' that states that if an engine is damaged by the use of their product, it will be repaired or replaced at their cost.

Boris88 piše:pa nista ja cu izgleda morati od prvog jula da stavim 200,300grama olova u rezervoar pa da tocim bezolovni thumbdown