Hi Ron,
Thanks for the reply.
The questioned I should have asked is "what causes the idle to drop by 150rpm with no change made to the settings on the carburetor?" It was unexpected to me.
I tend to approach mixture setting from the lean side (which you also suggest on your web page) with a initial setting of the jet 50 thou below the bridge. I have always found that from this setting that as I turn the adjusting nut down to enrich the mixture the revs increase to a max before falling off again. I am trying to find the "fastest idling speed consistent with even running" as the SU Tuning Manuals suggests.
"Tinkering" with the carbs is one of the pleasures of owning a SU carburetored car. When you get the tuning right it enhances the whole driving and owning experience. Carburetors and points every time for me. Fuel injection and electronic ignition for those who don't like to "tinker".
I've watched the John Twist videos many time and they are a great resource. Not sure that I ever remember hearing him say that having the idle drop by 150 rpm was "normal" but I'll certainly take another look.
Thanks for your comments.
Phil
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