Carburetor Vacuum

[may2021]

My '71 with a rebuilt Pontiac 350 has an issue at 70 mph.  It tends to stumble/surge as the secondaries are trying to kick in.  I have a Holley street avenger 670 cfm.  The mild cam is not making enough engine vacuum to open the secondaries consistently.  Other than switching to a mechanical secondary carb ... are there other easy things to do to remedy the situation?  I can live with it, but it isn't optimal.

Randall Reeves

[firebirdclub]

You have to change the spring on the secondary vacuum actuator it opens when you have less vacuum change the spring to keep it open or closed however you want it to operate it should only open when ur at or close to full throttle
Robert Breese