Have a 400 SBC running a 600 Vac Sec holley.

Cannot get the miserable little turk to stop running too rich (as indicated by a/f gauge and smell).

Cam is a low-lift jobbie, plenty of vacuum at idle (about 20"), will quite happily idle at 500 - 600 rpm.

Have opened secondary throats slightly, and have primaries closed past transition slots, but as I turn in mixture screws, idle speed keeps getting faster and faster, until screws are bottomed out.

At that stage, it still smells rich, and A/f gauge still pegged at full rich indication.

Will only show anything other than full rich under part throttle cruise at 60mph.

Have dropped float fuel level in primaries (as was boiling over on shutdown).

Removed K&N filter, and seemed to make mixture at cruise richer.

Any ideas out there?


Took K&N filter off him, and

Any other idea