Matt---One of the questions you asked was regarding the 2" SU carbs as
worthy replacements for what you now have. The HD8 is a fine carb, and
is on the Mark III Healey, as you know. The biggest advantage is the
wide selection of needles for this unit, all being available from Burlen
Fuel Systems, in England. You will want the Haynes Workshop Manual for
the SU Carburetor, for guidance here.
Proper selection of the needles is most important when building an
engine. I will say again that it is a crap shoot, unless one has an
air/fuel monitor, fed info from an 02 sensor in the exhaust. (Too much
fuel can be as bad as too little when it comes to making power) An A/F
monitor will give you a read-out along the rpm band under all
conditions. While it is entertaining to experiment with different
carburetors and their settings, it is rare that you will stumble on the
right profile without the benefit of this most useful device. A dyno
will report the power output, it won't necessarily tell you if you're
lean or rich along the way.
As mentioned by another enthusiast, the ZS carbs are also capable of
flowing a lot of air. Needle selection here is somewhat limited, unless
you are equipped to do a little conversion to make them capable in
accepting the SU needles.
I am envious of this great time in your life. I wish I could go back oh
so many years and repeat them!
Dick Taylor
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