vacuum break?

[Toronado]

Hi, I have a completely stock fresh rebuild 1970 Q-jet,
 Im having a problem with my secondaries.
 the vacuum break doesn't seem to be working correctly. I removed the vacuum break
applied vacuum it pulls in and sticks in. my vacuum break has
its linkage only going to the secondary air flap, and only acts
as a lock out i assume for low vacuum situations, it locks
out the secondaries? Do I need the vacuum break,
the secondary air flap only open when the engine
has enough vacuum, so why is the vacuum break there?
I know i can buy a new one, but I want to understand
its operation so im not misdiagnosing the problem.

[Toronado]

I found what it does, but i still dont see
it on many carbs, some carbs dont have
air flaps at all, I know race cars only.
but what condition have to be there for the carb to be able to handle it being completly opened
up and handle the fuel from the secondaries. couldnt the spring on the secondary air flaps being adjusted if you get a bog?

vacuum break....
"This function allows a smooth opening of the secondary air valve creating a smooth transition from primary to secondary circuit rather than plopping open creating a bog"

time to buy a new one and test it on and then off.

[Schurkey]

The vacuum break seems to be working exactly as intended.  You put vacuum to it; it pulled in and stayed there.  Why buy another???

The trick is to get it to RELEASE properly when you REMOVE the vacuum.

Is this unit on the front of the carb, or the rear?  If it's on the front, it's sure to also control the choke as well as the secondary air valve.

[Toronado]

When its pulled in with vacuum its sticks sometimes.
When the vacuum is released it stays in, locking out the secondaries.
I removed the unit and its just stuck, I can put compressed air to bring it
out but a min. of a 120 psi on my compressor then when vac is applied it just sticks again.
Its toasted, bad no good. Its at the front of the carb,
but the link does not contact/engage any thing on the choke. I tested my choke with the
unit removed the choke operated correctly, even a road test showed no problems even
when i opened the secondaries no bog just rocket power, even though I am going to put a new one on it is working without one-go figure. i found out this secondary opening timing from the break unit is critical for racing, the rate that it opens can vary depending on adjustment?

[Schurkey]

When its pulled in with vacuum its sticks sometimes.
When the vacuum is released it stays in, locking out the secondaries.
I removed the unit and its just stuck, I can put compressed air to bring it
out but a min. of a 120 psi on my compressor then when vac is applied it just sticks again.
Its toasted, bad no good.

OK, it's defective.

Its at the front of the carb, but the link does not contact/engage any thing on the choke. I tested my choke with the
unit removed the choke operated correctly,

What is opening the choke flap when the engine starts?  You need SOME kind of choke pull-off...

[Toronado]

I check to see if its cracking open on start up.
I started it the other day, cold engine choke
fully closed, my car started up in less than 2 seconds
and idle great. My new rapid fire plugs are really a plus
for start up and new starter. The choke is working,
but I will have to watch to see on start up for that instant opening
at start up to avoid an overly rich mixture for starting. But the car
does not mind not having the vacuum break gone, no joke, from start
at 40degrees to WOT to 100mph full temp, go figure. Of course I control my foot
and open the secondaries slowly and dont just floor it, so I am controling
th opening rate in some fashion.