| 216 End 
            of leaded petrol
 Roger 
            Parker (Green V8 4092) responded to a recent query from Gordon Hesketh-Jones 
            (Harvest Gold V8 1904) from Cornwall concerning the silent arrival 
            of lead replacement petrol (LRP) in the pumps during the Autumn of 
            1999. (Dec 99)
 Gordon reported 
              that he had run his factory built MGBGTV8 on unleaded fuel for seven 
              to eight years and covered 120,000 miles in doing so without any 
              problems. When he had lifted the heads out of curiosity recently, 
              he found the valves were in excellent condition. His use of unleaded 
              was based on contacts he had had with Land Rover at Solihull when 
              unleaded first came in some years ago. At that time Land Rover's 
              advice was unleaded was safe in low compression V8 engines. As many 
              members of the V8 Register have commented on how four star fuel 
              has silently vanished from the forecourt during the late Summer 
              and into Autumn in 1999 to be replaced by lead replacement petrol 
              or LRP, the subject of using unleaded was raised with Roger Parker. 
              The remainder of this note is based on his comments. "The information 
              regarding the use of unleaded fuel in the V8 comes from Land Rover's 
              power train engineering team at Lode Lane. The details are that 
              the specification for the MGBGTV8 engine was developed with an 8.25 
              to 1 compression ratio and the materials inside the combustion chamber 
              areas were specified to provide a full unleaded capability. The 
              engine was tuned to run on UK spec 94 RON fuel, so the 95 RON unleaded 
              is a higher specification fuel than the engines were built for and 
              no engine or ignition timing modifications are needed. Incidentally, 
              all V8 engines from October 1970 were built to an unleaded spec 
              irrespective of whether they were for a Land Rover product, Rover 
              car, Leyland Daf van or specialist car maker".  "Land 
              Rover has always been responsible for the V8 engine production and 
              still holds production records. The only additional note I would 
              add concerning the unleaded engine specification is that since the 
              1970s different, and possibly better, materials have become available 
              so more recent changes of specification may have further improved 
              the unleaded resistance of the V8 engine". | 
 "My 
              own very early ex-test Rover V8 block and crank (made in 1967) using 
              1976 SD1 heads with Vitesse valves has used 95 RON unleaded 
              since it became available with a 4 degree reduction in the ignition 
              timing specified in the manual. The engine continues to show no 
              sign of any problems and a continuing rise in recorded power at 
              the wheels confirms this. Further with a 10.25 to 1 compression 
              and modified heads that significantly improve volumetric efficiency, 
              no detonation has been noted, either heard or silently leaving tell 
              take marks". 
               "On the 
              subject of LRP, I worry that there is no UK British Standard for 
              these fuels. This means there is potential for problems arising 
              from mixing different brands of LRP in your tank or when mixing 
              LRP with any of the various brands of lead replacement additives 
              which may be used. I have heard from some people who have had no 
              problems with the change to LRP whilst others claim to have had 
              rough running as soon as LRP was added. At this stage there is no 
              clear evidence to support the poor running camp's argument, but 
              I always suggest that people try only small amounts of particular 
              brands of LRP at a time so if there is a problem, then there is 
              not a full tank of problems to use up! If after several short fills, 
              the car runs well, then I suggest that full use of that brand of 
              LRP can be made in future. What will not have been confirmed from 
              those checks is what happens when you are away from your home district 
              and you have to fill your tank with another brand which may be unknown 
              to you in terms of satisfactory running in your engine?" 
              "The removal 
            of leaded fuel has seen the arrival of a wide range of alternative 
            products or additives all claiming various advantages in terms of 
            lead replacement or octane substitution over the others. This will 
            continue to cause confusion. What those additives produce, either 
            individually or in combinations, in the exhaust gas content does raise 
            other questions to which I have no answers or suggestions at all". 
 
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              reserved by the V8 Register of the MG Car Club, PO Box 888, 
              London SW14 7YT |