No converter lock-up after swap

[je43278]

I recently purchased a 84 monte ss that originally had a 305 and th350c trans. The person I bought it from planned to drag race the car and had the entire engine compartment gutted and dropped in a 350 bored 60 over with other goodies, but that is all non-computer controlled now. They shaved the firewall, and chopped every wire not needed. The only wires left going through the firewall to the ecm are 4 wires that I believe go to the trans. The problem is I don't think the lock-up converter is working. I got under the car to verify that it is still the th350c with electrical plug and that its still connected. Everything looks fine there, but one thing that is not connected is a 4 prong plug behind the distributor. I assume this was for the computer controlled dist, but does this also affect the torque converter lock-up? I am unsure of how the trans is supposed to be wired, and how I can make it function again. I do not plan to race the car like they were going to so I would like to squeeze any mpg I can if I hit the highway. Thanks in advance for the help.

 

[joe_padavano]

I recently purchased a 84 monte ss that originally had a 305 and th350c trans. The person I bought it from planned to drag race the car and had the entire engine compartment gutted and dropped in a 350 bored 60 over with other goodies, but that is all non-computer controlled now. They shaved the firewall, and chopped every wire not needed. The only wires left going through the firewall to the ecm are 4 wires that I believe go to the trans. The problem is I don't think the lock-up converter is working. I got under the car to verify that it is still the th350c with electrical plug and that its still connected. Everything looks fine there, but one thing that is not connected is a 4 prong plug behind the distributor. I assume this was for the computer controlled dist, but does this also affect the torque converter lock-up? I am unsure of how the trans is supposed to be wired, and how I can make it function again. I do not plan to race the car like they were going to so I would like to squeeze any mpg I can if I hit the highway. Thanks in advance for the help.

The computer commands the converter lockup. The distributor provides the RPM input, the TPS in the carb provides throttle position data, the MAP sensor provides load data, and the VSS provides speed data. Without any one of those, the lockup will not work. If you do not plan to use the CCC system, then you need a non-computer lockup control, which can range from a simple toggle switch to an aftermarket system.

 

[je43278]

Ok. That makes sense to me. I wonder why they even bothered to leave the ecm connected at all then. Should I just finish removing it? I wonder if the VSS (vehicle speed sensor?) is still hooked up and the lock-up should be working off that. Another thing is I have never had this old of a trans in any car and maybe I just don't know what the converter lock-up feels like. Should I notice the rpm's drop a 4th time since its a 3 speed trans? I have had the 700r4 before but not this. Can you recommend a good online source for the aftermarket setup? Thanks again!

 

[jrm81bu]

Should I notice the rpm's drop a 4th time since its a 3 speed trans?

You would only feel the drop three time with the lock-up working. Once on the 1-2 shift, again on the 2-3 shift, then a third time when it locks up. Another easy way to tell if its working is, while driving down the road at a steady speed( say 60mph), tap your brakes just enough to get the brake lights to come on(not actually brake) and do not le tof the gas. You should feel it unlock then lock again.

 

[je43278]

Yeah, thats what I meant. 3 times. If that is the case then its definately not working. Just to get me by until I can buy an aftermarket setup.. of the 4 wires that go into the trans(the 4 prong plug), can I hook a couple to a toggle switch? I have been trying to search for an answer on this, but can't find anyone that has a straight answer.