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Chevy Chevelle Valve Body - Under Pressure

TCI's Constant Pressure Valve Body takes the stress out of adjusting your automatic transmission's troublesome line pressure adjustment

Mar 26, 2007

The TCI kit includes everything you need for installation, including the valve body, gaskets, O-rings, check balls, valve body separator plate (not shown) and 2/4 Servo (PN 376003).

If you've ever installed an automatic transmission, you know that setting the TV cable adjustment to achieve the correct standard internal line pressure and proper shifting is extremely important. Having the correct line pressure ensures that the internal transmission clutches clamp together tightly so power is transferred to the rearend. Without proper clamping pressure, these clutches will slip, creating destructive internal friction and residue that will quickly ruin your transmission.

Michael Murray is like most street machine enthusiasts, a guy with a cool car that features some upgraded performance goodies, a warmed up 350-cid engine and 700R4 transmission. Personally challenged to set the TV cable adjustment for proper line pressure and shift kick down, Murray and his classic GM muscle were the perfect test bed to try out one of the new TCI Constant Pressure Valve Bodies for 1987-92 GM 700R4 transmissions. A TCI exclusive, the Constant Pressure Valve Body ensures that internal line pressure stays at an acceptable level regardless of the TV cable setting.


With the pan drained and removed along with the fluid filter, we carefully removed the accumulator valve from the rear of the transmission, along with the fragile accumulator valve tube. After the attachment bolts are out, the tube is gently pried free.

Our installation was completed on a lift for photographic purposes, but this installation can be performed at home in your garage, making sure to first safely support the vehicle to create enough room under the vehicle to work on the automatic transmission. The TCI Constant Pressure Valve Body instruction notes that this installation is easier to perform with the transmission out of the car, but that is chiefly to help keep the transmission check balls in place up in the transmission case and changing out the 2-4 Servo. We found that if you use an appropriate amount of the proper transmission assembly lube, the balls will stay put. If there is not enough room between the 2-4 servo cap and the transmission tunnel, then removal of the transmission is required.

Before you begin, it is important to note that this valve body kit does not fit in pre-1987 700R4 transmissions. A simple way to test for the proper year transmission is to check and see if your transmission has an auxiliary valve body at the rear section of the pan. This component is inside the transmission fluid pan so you'll have to remove it to check. If you have one (see photo) you'll be good to go. If not, this kit will not fit your transmission so you will have to make other plans.


The lock-up clutch solenoid requires modification to work properly with the Constant Pressure Valve Body. While you will use the original solenoid, a new harness and wire connectors are included with the kit. They splice into the wiring in this manner.

"The kit was clear and complete, featuring all the parts required to install the valve body and other components," Murray stated. "This is an easy driveway installation, as it bolts in just like the standard valve body, no special tools or additional parts are required. With regard to the TV cable adjustment, that was really simple because I was not concerned with the line pressure setting, simply that the shifting points were to my liking. Having to only do one function was a big plus."

"I also liked that I could tailor my transmission's personality to my own wants," Murray continued. "The kit clearly spells out the various applications so you can choose between street, heavy duty and firm shifting. I built my transmission for street performance and picked the recommended modifications in the instructions. The transmission has a much better than stock quality shift now and, best of all, I don't have to be a certified mechanic to make TV cable adjustments. That's a load off my mind."



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