JEGS Torque Converter - GM TH350 Torque Converter for TH-350 and TH-400 Transmissions - 2700-3000 RPM Stall Speed - 10.75 Inch Flexplate Bolt Pattern - 500 Horsepower Maximum Applications

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The TH350 is an automatic shift, three-speed transmission. It is widely considered to be one of the greatest of automatic transmissions ever built. SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://www.chevydiy.com/gm-turbo-350-transmission-installation-guide/

This transmission makes an excellent conversion transmission due to its adaptability into most Jeeps. Both 2wd and 4wd versions of the 350 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly. Determine if the filler tube needs to go in before lifting the transmission into place, or if there is room to install it afterward. With many modern vehicles, the curve of the bellhousing and proximity to the firewall does not allow the tube to be installed after the transmission is in place and bolted to the engine.Install the transmission cooling lines and tighten securely. The fittings on the transmission should be held stationary with a second wrench to keep them from moving while the lines are tightened. In 1993, GM converted its 700-R4 four-speed to full electronic control, renamed it the 4L60E, and also retained its integrated bellhousing. When the LS engines appeared in 1997, the trans case changed to a bolt-on bellhousing to accommodate the LS engine’s revised bolt pattern. This also included a change in the torque converter diameter and flexplate attachment pattern. The large diameter converter pattern for the TH400 is an 11.5-inch pattern, while this new LS converter pattern is slightly smaller at 11.1 inches. Install and tighten the speedometer cable and any wires at the plug terminal. TH350s use a downshift cable that is routed up to the driver’s side of the engine and attached directly to the carburetor or throttle body linkage. The TH400s use an electric downshift solenoid that requires a wire to be attached to the terminal on the passenger’s side of the transmission case.

Once you have installed the torque converter, spin it several times to make sure there are no tight spots or binding. Do not attempt to install the transmission unless the converter is fully seated. Any attempt to pull the transmission up to the engine with the bellhousing bolts can damage the oil pump.

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All of these swaps involve interchanging flexplates and torque converters, and this can get a bit confusing. The attached charts spell out the different bolt patterns, as well as the converter patterns.