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On 5 Nov 2004 at 7:50, Steven Ayres wrote: > JasonW=> So I can't run the vacuum? > > Jim and I disagree on this, but I'm actually *running* an L distributor with > dual carbs, and the vacuum advance works just fine. Yes, we disagree. I agree that the effect won't be huge, since the amount of vacuum advance available from the 311 L dist is only about 1/3 of the mechanical advance, but it's still in the wrong direction. The one thing that I really don't know is how much vacuum the dual carb setup actually provides. If it is small, meaning that the vacuum can used on dual carb cars would have to be more sensitive than that on FI cars (which is quite possible) then this could mean that on his car, the (less sensitive?) FI vacuum advance has little or no effect. That would be equivalent to a FI car where the vac advance was not working. I know from first hand experience that one doesn't notice any change in performance, just a small decrease in gas mileage. In the end, I still don't recommend this. Steve is free to do as he pleases with his car, but I continue to believe that his usual good judgment is off the mark in this case. You can judge for yourself by looking at the advance curves in the Bentley manual. Consider what the result would be if the vacuum advance was added instead of subtracted (and vice versa) to the mechanical advance under various engine load conditions. BTW, I think we decided that there were late dual carbs (not for the US) which had vacuum drillings that WERE appropriate for use with distributors like this. I believe Mark Seaton, in the UK, is our resident expert on this. Perhaps he could start harvesting those throttle bodies from the US scrap yards and shipping them to us, where they would be very nice to have. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~