Hi Peter,
I completely agree with you. I will stick with the dual ZS for now.
Seems to me that if you add the triple ZS the air valves just ride lower
than with the duals. Maybe at WOT the dual ZS would not be sufficient.
Personally I think the only advantage of the triple ZS is the better
intake manifold design -- but that is only a beginners opinion.
I think there is much more evidence that the Falcon headers and a better
exhaust system will provide some benefits -- 10% to 15% seems to be the
consensus.
I can not find anyone who has gone to the triple ZS w/o making some
other change at the same time. I have never seen Dyno numbers on the
triple ZS. I may go with the triple ZS on the next pass, but I want to
do it when that is the only change that is made -- another reason for
doing the headers and exhaust now.
I guess there are other options -- like webers or SU -- maybe they are
better than the triple ZS. Time will tell I guess. But you have to admit
the intakes on the triple ZS are nice and straight. BTW, this is a later
head, and I'm using the longer runner swept intake manifold.
Kas shows a big HP improvement for the PI over the ZS, so there is
something to it -- improving the intake end of the thing. Exactly what
the answer to it is, is not clear to me. Maybe a supercharger -- but not
on this engine -- maybe the next one :-)
Don Malling
Peter Macholdt wrote:
> Don,
>
> I'm not sure who told you that the dual ZS will not keep up with the head,
> but according to Kas "The special carburetors fitted as standard to the
> TR-250 and the TR-6 as delivered in the United States can be used quite
> successfully for all of the modified engines except those to be used in
> all-out competition".
>
> I know that there are a lot of options out there (SU, Weber, triple ZS,
> etc), but I not aware of any dyno tests that show superiority over the stock
> ZS on street cars. All of the replacement systems have their own drawbacks
> be it cost, difficulty in tuning, or just plain overkill.
>
> My engine is very close to yours in terms of modifications. I chose to use
> the stock dual ZS set-up that came on the car. It runs great, but that is
> just seat of the pants (no dyno or track times).
>
> Nomex suit zipped, fire away.
>
> Peter
> '68 TR250
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