Question: Timed vacuum port

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

goodnigh - 28 Oct 2006 23:06 GMT

What is the purpose of a timed carb vacuum port?
My Carter 9637 SA AFB has three vacuum ports
in front at base of carb. The middle one goes to the
PCV valve, the right one (from front of engine) is
at full vacuum and is plugged. The left one is connected
to a TVS that has control over vacuum advance.
At engine idle there is no vacuum at the timed port.

mike

Reply to this Message

elaich - 29 Oct 2006 02:03 GMT

"goodnigh" <goodnigh1@mindspring.com> wrote in news:BvQ0h.1120$zf.58
@newsread3.news.pas.earthlink.net:

> What is the purpose of a timed carb vacuum port?
> My Carter 9637 SA AFB has three vacuum ports
[quoted text clipped - 5 lines]
>
> mike

Because you don't want distributor advance at idle. You want it under
acceleration and at speed.

Reply to this Message

Jim Warman - 29 Oct 2006 05:12 GMT

On most carburettors, we are given acces to both manifold vacuum and
"ported" vacuum... Ported vacuum is derived from above the throttle plate
but below the venturi.... Some carbs also have provisions for venturi
vacuum... but this is a very weak signal at the best of times.

Ford has used ported vacuum extensively for vacuum advance application.
During the late 70s/early80s, they also used both ported and manifold vacuum
for the distributor through a temperature sensitive vacuum valve (manifold
vacuum when cold - ported vacuum after warm-up). Ported vacuum has also been
used for EGR operation. Venturi vacuum was used in some years to control a
vacuum amplifier which, in turn, controlled the EGR....

> What is the purpose of a timed carb vacuum port?
> My Carter 9637 SA AFB has three vacuum ports
[quoted text clipped - 5 lines]
>
> mike

Reply to this Message

Rate this thread: