Thomas Colt, Ill, VTR Member 0205, did some Investigative work as a result of the leaded gas phase down we have been reporting on in The English Channel over the last year. Below is a synopsis of the correspondence between Mr. Colt and the AMOCO Oil Company.

To AMOCO CU Company,

    I used Amoco Super "no lead" in my 1967 Triumph for five years with neither knock nor whimper. When I restore it for the road, its back to your pumps that I’ll be driving. When I do, will I be able to use AMOCO Super? If not, what is the difference between Amoco of today and that of the past?

Thomas Colt, III

Dear Mr. Colt,

     Amoco Premium Lead-Free in the 1950s and 1960s was the same pure Hydrocarbon gasoline it is today. Nothing was added then nor now to protect valves. Our experience was good and continues to be so concerning valve wear in older cars designed to operate on leaded gasolines. I dare say, we would not be in business today if we had caused problems of this nature. In this regard, a Product Information Sheet outlining our position is attached for your review.

John B.Shaw, Coordinator

Amoco Customer Relations





Does Use of Lead-Free Gasoline Cause Valve Problems?

     We occasionally hear comments that using lead-free gasoline will cause valve problems in older model cars. We do not believe there is any practical basis for this claim.

     When use of leaded gasoline began in the 1930s, carmakers experienced serious problems with burning of exhaust valves. Lead deposits would accumulate between the valve face and seat and prevent the valve from closing tightly on its seat. Cracks or "gutters" would form in the lead deposits, which made the valve leak, overheat, and burn. After considerable development, carmakers alleviated the problem by redesigning engines with sharper valve seat and face angles, narrow seat widths and higher value spring forces, and Induced or forced rotation of the valves. These changes increased the contact pressure between the valve and seat, and caused the valve to grind out offending lead deposits. Even so, value burning continued to be a chronic, but minor, problem with leaded gasoline.

     These measures to eliminate valve burning are unnecessary with lead-free gasoline. Under normal operating conditions, an engine designed to tolerate leaded gasoline will run without any difficulty on lead-free gasoline. It Is possible to fail exhaust valves in laboratory engines operated on dynamometers by running them continuously at very high speed and power output. Without the lead deposits present, the valves may wear or "recess" excessively into the softer seats. However, the conditions necessary to cause value recession do not occur in normal driving, and can be attained only under highly unusual (and generally illegal) driving. Most people could not drive that way even if they wanted to.

     All passenger car engines built after 1974 and most engines built after 1971 have hardened valve seats, and valve distress cannot be induced in these engines even in dynamometer tests. Most commercial gasoline engines are equipped with hardened valve seat inserts, which prevent distress under any type of operation.

     We, of course, have marketed lead-free gasoline in the eastern and southern states for over 70 years. Our customers have driven millions of miles using this gasoline in all types of cars without valve problems. We think our long field experience conclusively demonstrates that lead-free gasoline does not cause valve problems.



     VTR members that would like to obtain a high-octane leaded fuel for their Triumph should look into the availability of racing fuel. A number of possibilities exist, with Sunoco’s CAM2 perhaps being the most widely available. As an example, in north New Jersey, a local Sunoco station sells it at the pump. It is not unreasonable to expect that it can also be purchased at the pump in other areas with a little, searching on your part. A good place to begin looking is in the areas around a major automobile racetrack

     While the cost of these fuels is not cheap, averaging around $3 a gallon, a few gallons of leaded racing fuel mixed with regular leaded or unleaded premium in your tank will provide excellent results in drivability and performance. As a rough indicator of the final octane resulting from mixing a leaded racing fuel with either leaded regular or unleaded premium, you can use the graph below. It Is drawn using 110 Octane CAM2 racing fuel combined with Sunoco leaded regular (89 Octane and Sunoco unleaded premium

 One thing to keep in mind about the graph, the effect of lead when used in gasoline is not a linear relation. What this means is that If you start with an unleaded gasoline and add one gram of lead per gallon and it results In an octane boost of say, 3 points, the addition of another gram per gallon will not result in an additional 3 points gain. The actual Increase for the total of 2 grams per gallon would be something less than 6 points.

     If you have followed this so far, and If you realize the grams per gallon of most leaded racing fuels is in the area of 4 grains per gallon, you will see that what you actually get in a final octane rating when mixing the fuels as indicated by the graph is an octane rating that is probably higher than actually indicated, except at the two end points. That result would likely be most affective when mixing unleaded premium with the racing fuel.

     When you consider the time and money most of us have invested in our Triumphs and couple that with our desire to have our TR or Spitfire running well for many years, the additional cost associated with this gasoline mixing procedure is a small price to pay. The reward of improved performance and minimization of engine damage due to using unleaded fuel in engines that need it or from detonation due to low octane fuel is certainly worth considering.

Bill Sohl, VTR President