Sujit :
The vacuum advance increases engine efficiency by advancing the spark under
partial load conditions. (It also increases NOx emissions.) Not having it
will reduce fuel economy, and may increase overheating. Note that later
US-spec TR6 did not have a vacuum advance (and IMO were poorer without it).
The vacuum retard was a US-mandated emission control feature. It is active
only at idle. Not having it may cause your idle to be too high. Note that the
dynamic timing figure given assumes the retard is active, so if the retard is
not functional, you need to use the 'static' timing figure (which ISTR is about
10 BTDC), even when setting timing dynamically (with a timing light).
Randall
On Tuesday, October 03, 2000 4:50 PM, sujit roy [SMTP:sujitroy@hotmail.com]
wrote:
>
> What is the main reason for having a vacuum advance/retard in the
> distributor? What are the effects of not having it connected?
>
> Sujit
> _________________________________________________________________________
>
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