th350 vs th350c

[blackcherry81]

well i finally got around to installing the b&m shift kit in my trans and turns out it wouldnt work because my transmission is a th350c at least thats what ive concluded there is a wire going into the transmission but its cut off about 6 inches outside of the case so the lock up torque converter must not be functional my question is is there a regular th350 that has a wire going into it or does the wire mean i for sure have a 350c and if so how to hookup the lockup again and what exactly does the lockup tq converter do and if it will improve mileage performance anything any info or opinions would help me alot thanks alot new to the site and its helped me a few times

[RUSHNBOBO]

If it's one wire it is not a 350c ...some THM350 in the seventies had transmission controlled spark (it doesn't allow any vacuum advance in first gear, & a vacuum delay after the up-shift.) this is a smog device and can be plugged if not required.

THM 350c's will have a 2 or 4 wire harness near the shift linkage on the drivers side.

[blackcherry81]

thanks for the info man this is a pic of the plug that was in the transmission its missing a wire on one side and the other wire is only about an inch long previous owner must have cut the wires or something does anyone have any idea as to where these wires go id like to hook up this "lock up" and see how it works also on the side of my transmission is stamped "mv4" ?

[RUSHNBOBO]

Yep that's a "C" 2 wire lockup plug...........

2 hole.... put 12 volts to the front hole , ground to the rear hole. Switch the ground or the 12 volts...... does not matter. You can just use a toggle for lockup. Or wire it up like original to lockup automagically........

Hit a salvage yard that has late 70's early 80's GM's. The carb non-ECM cars had a firewall mounted vacumn switch that controled the lockup. The fix is easy but the part may not be easy to find.

[blackcherry81]

cool thank you for the help much appreciated i think ill just put it on a toggle and see how it works out. will i be able to tell when it actually locks up?and im guessing the only time i should use it is when im cruising in 3rd gear to get better mileage and when i go to slow down just turn it off or what? sorry lol i had never even heard of lockup torque converters until a few days ago

[RUSHNBOBO]

Originally Posted by blackcherry81

cool thank you for the help much appreciated i think ill just put it on a toggle and see how it works out. will i be able to tell when it actually locks up?and im guessing the only time i should use it is when im cruising in 3rd gear to get better mileage and when i go to slow down just turn it off or what? sorry lol i had never even heard of lockup torque converters until a few days ago

You may or may not feel it ....it's kinda subtle, try stomping on the go pedal in high gear and you should feel a difference when toggling the switch between lock and unlock just to see if it's working.

If you hook it up manually use it as soon as u come up to cruising speed in high gear.....it will save some precious fuel and keep the fluid temps down.

[beamn7]

In case you want to run the Vac switch so as not to forget to hit the switch and stall 'er out....

http://www.classicparts.com/1982-86-...ctinfo/53-604/