4 Barrel Secondarys

[ernie d]

Hi guys & gals........

I have a problem with my 69 Big Block, the vacuum secondarys are not opening at all. It's fast as 2 barrels go, but...... :L

It is a Holley 4150 side inlet 600 cfm model with vacuum secondarys.

Any advice?

Thanks,

Ernie

 

[Eric R.]

With the engine off, open the throttle and work the secondarys by hand. If that checks good then remove the complete vac secondary unit (couple of screws) and test with a vac pump or your mouth with a small chunk of vac line held over the opening. (note, there should be a small cork or rubber gasket present betweeen the secondary unit and the main body) If the diaphram does not pull then replace it. Also check the vac passage from the side of the carb inbound to make sure the passage is clear. Lastly it is possible that the secondary spring has been replaced with a heavier unit causing it to not open soon enough. Get a secondary spring set from your local speed shop and install the proper spring for your application in the instructions.