Yes, ZS's run fine when functioning properly, but their complexity gives more
opportunity to malfunction.
personally, I would not say that ZS carbs are superior. Both SU and ZS use a
needle to fine tune the mixture and this tuning is dependent on manifold
vacuum. The ZS needle is not intrinsically better than the SU's. The ZS air
flow is not intrinsically better than SU's. So, I would have said that with
the exception of choke functions, the ZS is not superior to SU, instead, they
are equivalent. Since the SU is simpler, then IMHO the SU is the superior carb!
-Tony
-------------- Original message --------------
> Message text written by INTERNET:spamiam@comcast.net
> >Dave, After some thought, now I agree with you. After I replied to your
> message I saw Randall's. I then gave more thought to the issue (better
> late than never). I realized that I did not KNOW the effect of any
> potential idle air passages and whatnot on the emissions ZS carbs. I also
> dd not KNOW what the CO reading is when set the old way, and I did not KNOW
> how this compared to the setting when done the "new" way. I am not
> positive that the needle profile was not changed in the idle position to
> alter the idle characteristics which was not represented further along the
> profile. (I.E. the profile might be set to be lean at idle, and if set to
> "correct the old way" at idle then the rest would be too rich). (I still
> would have thought that setting the emissions carbs the old fashioned way
> would be no worse for CO AT IDLE than the same technique for the old carbs.
> I guess it is just not what the rest of the profile was designed for, and
> the rest of the mixture will not be ideal)
> I still think that I deserve the beers because I did give the correct
> ultimate solution. Dump the crappy old emissions ZS carbs!!!!!!!
> <
>
> The point that is being glossed over is the fact that we are setting the
> carbs at idle and expecting the settings to be correct for running
> conditions (under load, at speed) and how you set the at-idle setting
> depends on how the needle is profiled in the idle portion vs the at speed
> portion. And the emissions era needles are indeed reprofiled for obvious
> reasons so alternate adjustment techniques are requires.
>
> Strombergs are fine carbs and work well once you stop trying to adjust them
> using SU techniques! Compared to Strombergs, SU are primative. They were
> designed to be adjusted using stone knives and bear skins. But they are
> not up to the task of clean emissions. Strombergs are refined enough to
> meet the challange.
>
> They are also capable of high power output. A friend of mine who races
> SCCA says that TR6's are not allowed to run Z-S carbs and are required to
> run Webers choked down for this reasons.
>
> Dave
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