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On 7 Dec 2004 at 23:11, Steven Ayres wrote: > Remember also that there were lots of happy motors moving cars, cargo and > people around long before the oil companies started putting lead in the fuel > and charging more for it. This is true, but it needs to be viewed in context. Early gas had no lead in it, but lead, in the form of tetraethyl lead, was introduced in early 1923 as an anti knock agent. For decades, the choice at the pump was "Regular or Ethyl," and the amount of lead slowly increased as the compression ratios of our engines increased. It's true that most of the engines of that era just had the valve seats ground out of the base cast iron that the head was made from, but most of those engines were low rpm, low compression, and low output. The higher output engines were the ones which used Ethyl anyway, so they didn't have a problem. The others had few problems, simply because they were so lightly loaded. The other thing to consider is that valve metallurgy was primitive in the early days, so valve jobs were a very frequent thing. Given road conditions and prevailing speeds in the 20s, I'd guess that very few people put 1000 miles per year on a car, but even then a car was likely to get a valve job at least every 10 years. I think most of us forget how common a valve job used to be compared to today. I believe that wear in early heads was often cured by installing valves with oversized stems. It's possible that valves with oversized heads were also available. All of these things made it possible to live with cast iron heads and without lead. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~