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On 8 Dec 2004 at 9:03, Steven Cooper wrote: > I am using premium unleaded fuel (98RON) with an upper valve lubricant > additive. We can no longer get leaded fuel in Australia It's the lead that causes fouling, so fouling is extremely uncommon with unleaded gas. OTOH, if your additive has lead in it, it may be the problem. VW heads and valves haven't needed lead since at least the '70s. There are some early valves floating around which would be a step backwards, but if the latest valves were always used in a valve job then this engine does not need any additive of any kind. Our valve guides have been bronze since ?, at least the 60s, so they don't need lead. The valve seats are hardened steel since the same time, and they don't need lead. The only thing that changed later was one of the valve stems got a chrome plating in around '71 that made them no longer need lead. Unplated valves are still available; they are cheap, but you should always spring for the later plated ones. If your additive contains lead, then it's possible that you're overdoing it and this is leading to lead deposits. The W8AC plugs are the right ones, so they are fine. The float valve shim washers are something to make sure to get right. I think you might even need both, for a total of 1.5 mm. And engine that is running rich will run cooler, which may keep the plugs from getting up to their self cleaning temp. So the richness and fouling can affect one another. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~