Hi, John.
The one thing to note about the '69 carbs is that the vacuum advance
is "ported" (may be so on other models, but that is the only year I am
familiar with.) At idle, there is no vacuum advance (the hole from
the connector tube into the carb body is upstream of the throttle
blade edge;) as the throttle is opened, the vacuum is applied, and
somewhere about 10% throttle (from memory) the vacuum of the manifold
is totally applied to the distributor's vacuum servo.
HTH,
Donald.
(feel free to email me for more info if this is insufficient.)
> Date: Sat, 06 Apr 2002 07:58:17 -0800
> From: John & Judy Tones <jtones@shaw.ca>
>
> Hi All - on my '69 MK III, the Dual SU carbs have me scratching my head !
> The vacuum port on the front carb (only vacuum port on the set-up) does not
> have any vacuum what so ever when the engine is running.
> I have had an ongoing problem of timing with the car ever since I bought it
> and only just now realized that a big problem is no vacuum advance <duh !!>
> Anyway, on looking at the carb in question, I cannot see ANY hole from the
> port into the carb throat. Have I got a carb that was mis-manufactured or
> what is going on ?
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