Nolan Penney wrote:
>
> A pair of dual HS2's isn't bad though. Especially when compared with a
>single ZS,
> double especially when looking at the runners on the late ZS manifold (very
>small).
It is worth nothing that early MG Midgets come with dual HS2 carbs
and it is a semi-popular modification to go from that to a single
HS4 carb. (mostly using Mini tuning parts)
The cross sectional areas are as follows:
Dual HS2s (2 x 1.25 inch) = 2.454 in^2
Dual HS4s (2 x 1.50 inch) = 3.535 in^2
Single HS4 or ZS-CD150 = 1.767 in^2
This is pretty simplistic, but in terms of raw airflow
the HS4s are way up there, with the HS2s somewhere behind
and frankly not far above the good old ZS.
> I have an '80 Spitfire. With the single ZS, the car was not happy above 40
>mph. It
> strained its guts out. Interstate highway's were a writeoff, I just wouldn't
>venture
> out onto them.
I would think you had some major problems with
that ZS. I ran the ZS for a while, and it was
unremarkable but definitely acceptable. The car would
go way faster than I wanted to go in it!
I have dual HS4s on my Midget 1500 (same engine as
your 80 spit). The car is faster now than before, but
there was nothing wrong with the car when it was a
single ZS.
I do beleive that to go from a single ZS to a dual SU is
a decent upgrade, but I wouldn't expect miracles.
Most of the complaints against ZS carbs are exascerbated
by people running old ZSs that aren't in tune or have
problems. If you go from a clapped out ZS with a holed
diaphragm to a set of SUs, the change will knock you
down, but that's not really a fair comparison...
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
"Groucho, not groucho. Groucho, not groucho. Groucho..." - Duckman
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