vacuum secondaries not working

[WZ JUNK]

I have a Holley 4160 750 cfm vacuum secondary carburetor.  The secondary is not working.  I have tried all of the optional springs.  I have verified that the linkage is not binding.  I replaced the diaphram that actuates the secondary and verified that it works.  I removed the tiny check ball.   The engine has plenty of vacuum.  I placed a zip tie on the actuator shaft of the diaphram to verify that there is not enough movement but there is some.

I have read technical stuff from Holley.  I have read on the net.  I have called Holley, I have watch youtlube videos.  I am stumped.

[kb426]

How about connecting your mity vac to the port and see if the diaphram retracts?

[chimp koose]

Isnt there a gasket between the vacuum pod and the body of the carb ? Maybe its toast ?

[WZ JUNK]

A friend brought me a carburetor like mine today for us to compare.  I changed out his vacuum actuator.  It worked.  We compared the two.  His diaphragm had a softer feel.  I had used a replacement interchange non Holley from the local auto parts store.  I am ordering the correct Holley part now. He is going to let me use his until the mine arrives.  A good friend.  

[kb426]

Good!

[chimp koose]

stiffer diaphragm would act like a vacuum leak to the diaphragm . I had not even thought there would be a difference in stiffness , learned something today !