Quote:
Originally Posted by yayo_ayala
Fred, the point that I was making in regards with the XDi - the tunning is not ideal. I have no doubts that you car has a big punch. Review my comment from the perspective that once you change compression, fuel, cams, headers and twin plug - tunning the car will help you to take full advantage of those modifications.
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The timing control on the XDi system is pretty sophisticated. In addition to "built in" adjustments, there are 4 infinitely adjustable timing controls on the control box for fine tuning. Knob #1 sets the initial timing between 400 and 1000 rpms, knob #2 sets timing above 3000 rpms, knob #3 allows timing advance (or retard) above 8000 rpms, knob #4 sets the ignition cutout point or rpm limiter. The actual advance can be measured using a digital voltmeter. An example "starting point" for timing a street engine is recommended to be Initial knob = 12 degrees, 3000 knob = 21 degrees (which is added to the initial knob), 8000 rpm knob = -2 (subtracted) and knob 4 at some reasonable level. On my engine it is set at 7500 rpms. Also, keep in mind that my system is about 6 years old and current units will have been improved significantly. The system fire each of the two plugs from different coils to insure full voltage to each plug. The instructions that came with the system are much more detailed and you can find a copy on the Clewett web site. Whatever you decide to do with your engine, good luck! Just remember, it is always cheaper to do it right the first time!