> One thing about some of the PCV-tube equipped SU's.....some later cars
> also had
> SU's with poppet-valves incorporated
> in their butterflies (which allowed extra air
> into the intake manifold to clean up combustion emissions under
> deceleration) along with "spring-loaded" needles.
>
> You don't want these, IMHO.
>
> You want the earlier less "maintenance intensive" PCV-tube equipped models
> with plain butterflies and "fixed"needles. These also are better for
> driveability (IMHO) as without poppet valves, revs drop much
> faster on deceleration for "more" and
> more instantaneous compression (engine) braking. Otherwise it takes years
> for the
> revs to drop off and brake wear increases
> accordingly.
I agree that the poppet-valve butterflies are less than desirable, but more
because they are too much bulk in the breeze (especially at WOT). Easy
to get a set of solid butterflies from Joe Curto along with a new throttle
shaft.
Spring-loaded needles, OTOH, are not all bad. True, they do produce
wear on the needle and jet, but they also produce more predicatable and
consistent flow since the needle is on one side (less of a laminar effect?)
instead of in the middle.
David Lieb
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