Introduced in 1986, unleaded petrol eventually superseded leaded four star, which was phased out in the year 2000. Engines being produced in the leaded era relied upon compounds present in leaded petrol to protect their valve seats, compounds that you won’t find in unleaded. So if you’re a classic car owner, you run serious risks using this more modern, widely available fuel type for an extended period of time. That is, unless you invest in an unleaded conversion, as offered at SRS Engineering in Sutton.
The process of converting an engine to run on unleaded fuel depends on the specific make and model of the engine. However, there are several general steps that will nearly always be taken.
Firstly, we replace the valve seats. Valve seats are located in the engine's cylinder head and are responsible for sealing the valves against the combustion chamber. Leaded fuel contains additives that lubricate the valve seats, but unleaded fuel does not. Over time, this can cause the valve seats to wear down and lead to engine damage – hence the necessity of an unleaded conversion if you wish to run on it for any decent length of time.
Due to the bespoke, nuanced nature of an unleaded conversion, it should never be attempted by amateurs and non-specialists. Instead, if you’re based in or around the Epsom, Croydon, Kingston, Streatham or Wimbledon areas, visit SRS Engineering. Our Sutton workshop is manned by technicians with over 50 years of experience, much of that time spent handling unleaded conversions to the highest standard. It’s also fitted with the equipment that’s simply a pre-requisite for this kind of complex engine work.