09 May 1997, Martin Libhart <mlibhart@feist.com> wrote:
>
> rgb@exact.com wrote:
> > Why would you care? Best I can figure this was a device
> > for spoof'ing the emissions idle laws at the time. Likely
> > didn't reduce pollutions and I've fixed several cars where
> > it caused so much dist wear that the dwell and timing
> > were affected.
>
> Okay, okay, I confess - originality is my primary consideration here!
> To heck with performance! Well, I don't really mean that, either.
> I just want to buy more expensive parts for my Triumph... yeah,
> that's it, more expensive parts for my Triumph!
Yes, emissions, but also a smoother running car at idle for the mass
(American) market. An engine running with a lot of advance at idle is
difficult to adjust for a smooth even idle. In Europe, drivers are
typically more enlightened about sporty cars. However, many American
buyers bought sportscars because they were cute or had the right image...
then expected them to be as smooth and trouble free as their Detroit
grocery getter.
Vacuum retard pulls off some of the advance at idle only. The car idles
easier, and produces fewer emissions for the sniff test. As soon as the
throttle is opened, the vacuum is broken and it's back to normal.
Neither issue (emissions/ smooth idle) is usually very important to the
typical enthusiast. Defeating the vacuum retard, advancing the idle
timing and quickening the centrifugal advance rate are all pretty normal
performance tweeks. The performance enthusiasts who care about that stuff
are usually more tolerant of a "hunting" idle.
Regards,
Tim
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