mustang66289

I tried adjusting my carburetor with a vacuum pressure tester and no matter which way i adjust there isnt any change in pressure stays at about 8 cm Hg. Do i have some kind of problem with the vacuum? any tips for adjusting would be greatly appreciated.

Jonk67

Pics and more information would help, some carbs have more than one vacuum port, one is manifold vacuum (full) and on is ported (varies on RPM) which is what the distributor uses. May have a vacuum leak from rubber hoses, gaskets, carb gaskets, etc.
If I remember correctly full stock vacuum is 17-19?
Jon

mustang66289

2+2GT

Where are you connecting to get the vacuum reading?

kalli

yep, where exactly did you hook up the vacuum gauge in your pictures?


Jonk: both change with rpm and throttle plate position. The single only difference between ported and vacuum advance is when the throttle plate is closed. Someone once graphed it with a throttleplate position sensor and measured the vacuum. from 5% throttle open they produce the exact same reading. Only that with ported vacuum the vacuum is very low when TP is closed (as it measures above TP), and manifold vacuum was of course at its highest with TP closed as it measures below. once you start opening the TP they measure the exact same vacuum. reason for this was so that at idle the ignition was retarded (emissions)

mustang66289

Disconnected the vacuum advance from distributer and tested from there