Valve Body Help - Shuttle Valve

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Ricks70Duster340

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OK valve body guru's: I have a valve body (with part throttle kickdown module) that is not shifting correctly and I need some assistance to understand why. It was modified by a known trans builder that everyone likely knows. That is beside the point though. I have an old shift kit instruction manual from Fairbanks that shows the throttle pressure valve being ground down & spring replaced for competition level. My VB has that ground down. I have an old VB that I could replace the throttle pressure valve & spring with stock ones. Even with the kickdown cable backed way off, the trans will downshift from 3-2 at 25MPH while decelerating and my foot is off of the gas.

Another issue I'm having is the 1-2 shift is soft. I've had transmissions that the 1-2 shift was very fast and chirped the tires. We are far from that with this one. It shifts OK, but kinda non chelant. The line pressure is set per my old shift kit to be increased to street level. The last issue I'm having is when I accelerate, the 2-3 shift does not happen until I take my foot off of the gas a little. The space between the throttle pressure arm and the valve is set to 1/8" per the old shift kit instructions. The other odd thing I see with the VB is the shuttle valve has been modified. When I took the end plate off and removed the valves, the shuttle valve had two valves stacked together with a spring that pushed the inner valve way out. This is very different than other configurations I've seen where the inner valve is held with a small C clip and only sticks out a little. The one I have does not have a C clip and sticks out a long way.
 
Is the kickdown linkage/cable set correctly, is the kickdown setup for a 2 barrel or 4 barrel carburetor?
 
Is the kickdown linkage/cable set correctly, is the kickdown setup for a 2 barrel or 4 barrel carburetor?
Lokar cable. I verified that the cable is relaxed at idle (kickdown lever is full forward) & pulls the kickdown lever all the way back at full throttle.
 
Do your parts look anything like this?
 

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When I took the shuttle valve assembly apart, there were two of the small circular plugs shown on the left stacked on top of each other. Under those was the black spring then the longer shuttle valve.

download.png
 
Interesting. The valve in the VB does not have a spring outside of the casting nor does it have an E clip. That setup is likely why there is no 2-3 shift until I lift my foot from the gas. Thank you for the explanation/diagram.
 
Rick, not knowing what other changes were made, it is hard to tell what exactly is causing the troubles you are experiencing.
 
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