Thread: Tuning a series I with a Vacuum Gauge....

The ideal place is to take the vacuum reading is from the manifold.
The piccy is the small vacuum port (the small holes at abt 5 O clock)

At idle the vacuum port is or nearly covered by the butterfly.
so you need a bit of throttle to make the vac advance work anyway ,,

To use a diagnostic vacuum gauge, you need to connect it to a manifold port. That vacuum port at the butterfly is for distributor advance.

Originally Posted by spudboy

After some assistance from Mildred & Groucho, I have found the vacuum port on the carbie and attached my vacuum gauge.

At slow idle, the vacuum reading is non-existant, in the white area of the gauge near zero.

If I up the idle a bit (maybe 1000-1200RPM) I can get the needle to go up to the end of the red section where 10 inches of mercury is indicated, and then I have been rotating the distributor to get the highest reading.

Is there a proper RPM at which I should be doing this?

Is it normal to have such a low reading at slow idle (I reckon it idles at about 400 or 500 RPM)?


I've taken the aircleaner off BTW - just to get access but I cant think this would change anything.

you have to drill and tap into the INLET manifold to attach the vacuum gauge.
No other place is correct.
Drill and tap
Drill and tap
attach
read the gauge

meus alius car est quoque a Morgan sic utor