[Chevelle-list] Fw: Vacuum advance

[KW]

Lots of the emission controlled vehicles used a vacuum retard on the distributor, at idle it retards the vacuum with manifold vacuum.
Most vehicles use a vacuum advance distributor which uses ported vacuum (no vacuum at idle) to add additional advance to the distributor as the RPM's increase. If you are insure if you have a vacuum advance or a vacuum retard distributor you can hook up a timing light, draw a vacuum on the port on the distributor and watch the timing. If the timing retards with the addition of vacuum then you have a vacuum retard distributor. If the timing advances then you have a vacuum advance distributor (and need to use ported vacuum [no vacuum at idle] for your distributor)

Keith
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://chevelles.net/pipermail/chevelle-list_chevelles.net/attachments/20070521/33321075/attachment.html