How does the secondary diaphram work?

Joined
Nov 22, 2004
Messages
139
Does the secondary diaphram rod "pull" the secondary throttle plate open OR does it just allow the secondary to open via a spring load under vaccuum?
Just wondering if mine is hooked up right, I can reach down there with the engine off and pull the rod freely without the secondary moving, understanding that with the peddle not depressed it prevents the secondary from opening.
 

RHINO

 
 
Joined
Dec 23, 2003
Messages
3,770
Location
Payson, AZ
oh man,,, trying to remember. seems like when i was rebuilding mine and playing with the secondary it "allowed" the valve to open. i remember i put vacuum to it and watched it move to make sure it was working.
 
Joined
Mar 6, 2004
Messages
685
Yes, it is vaccum operated. Also can't be seen operating unless the truck is moving from what I recall.
 
Joined
Apr 30, 2005
Messages
253
Location
Down South
IIRC the linkage is set up such that the secondary doesn't engage to pull open until the primary is partially open.
 
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