I need education on the Thermoquad "staged accelerator pump" , that gives an additional shot when the secondaries open

[Brooks James]

found this in David Emanuels Carter Carburetors

the accelerator pump arm in the pic , you cant tell if the slot that is oblong as the pump linkage arm is in place is in place
in the pic the bottom hole looks like a circle, and you can see from the pic of the one I am familiar with, that it is slightly oblonged

or is it an optical illusion and they are both the same

if they are both the same, what am I not seeing that would provide an extra shot

OR

Is there different arm ?

is he using a wordy explanation to explain something that has been already happening that I am unaware of ?


pics comimg

 

[rumblefish360]

The pump shot plunger is spring loaded and moves a certain amount for the initial pump shot for the primaries. Then there is a time when the throttle arm continues to move without the pump shot linkage engaging the pump shot lever connected to moving the plunger. Depressing the throttle more moves the linkage up into the taller slot. The linkage is shoved to the top pushing the arm upwards some more for a second pump shot.

 

[rumblefish360]

Picture 1 - top. Throttle position at rest/idle/very light throttle.
Picture 2 - middle. Throttle @ 15/30%-ish open.
Picture 3 - bottom. Throttle is mostly too fully open.

This is the progression of the link from the bottom of the throttle arm connecting the pump shots lever positions on a 1973-340, manual transmission TQ carb.

Welcome to my garage…..

 

[Brooks James]

Picture 1 - top. Throttle position at rest/idle/very light throttle.
Picture 2 - middle. Throttle @ 15/30%-ish open.
Picture 3 - bottom. Throttle is mostly too fully open.

This is the progression of the link from the bottom of the throttle arm connecting the pump shots lever positions on a 1973-340, manual transmission TQ carb.

View attachment 1716148700

View attachment 1716148701

View attachment 1716148702

Welcome to my garage…..

would that make it a double pumper lol

 

[Bewy]

Yes, sort of......

Not sure which model # was the cut in, but at some point a small portion of the remaining pump shot was saved for the opening of the secondaries.
Having used these carbs for 45 yrs, I have never had the need to use the inner hole on the acc pump arm. The triple pri boosters provide a very strong signal & a heap of pump shot is generally not needed.
Yes, these fabulous carbs continue to amaze us.......