John: Good question, but like I mentioned I've never used the tool myself. As
I understand it with the SU once the mixture is correct at low air speed
through the carb it is good throughout the range of operation. This is
probably an over generalization, since I 've heard of people "tuning" the jet
needle by grinding away material at points along the taper of the needle to
provide variable fuel flow at different rpm ranges in conjunction with
different advance weights in the distributor, etc. Another tuning method,
albeit even more expensive, is to install an O2 sensor and black box to
indicate mixture strenght during running conditions, and tuning the carb(s) to
provide the optimum mixture strength. I have a Holley Projection fuel
injection system on my 83 Range Rover 3.5 V8 with such a system. I can tune
the control unit for idle and mid range using this. Under heavy accelleration
the conventional methods of looking for black sooty exhaust and dirty plugs
still apply.
Cheers, Andy Blackley
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