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Discussion Starter · #1 ·
Im putting together my first 2wd truck and ran into something ive never come across in any of my 9 4wd trucks.Im trying to install a turbo 350 but after purchasing it and puting it in the truck i realized it had a 4wire plug im taking is for a converter lockup like on 700r4.Can i still run this transmission without the plug my truck doesnt have one. Plus im running a 3000 stall if that matters.
Thanks
 

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Short box ... Welcome to Hotrodders.com

When posting a new thread , please give these guys an idea what the subject matter is inside the thread.

I edited the thread title for you

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WFO
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Short_box said:
Can i still run this transmission without the plug my truck doesnt have one. Plus im running a 3000 stall if that matters.
You have a TH350 "C" (lock-up TC) tranny.

If the 3000 stall TC isn't a lock-up model, the tranny will need modified to use the non lock-up TC, IIRC. You might be better off starting off w/a non lock-up TH 350 tranny in the first place but this depends on prices for modding the "C" tranny compared to the cost of a different, good TH350 non "C" core.

A lock-up TC will function not locked up, BUT they slip quite a bit more when not locked up than a non lock-up TC- so heat will be higher, and efficiency lower w/o lock up.

The difference between not locked up and locked up is several hundred RPM; you feel the lock-up as if the tranny shifted into another gear in actual use- it's that noticeable- at least in my '80 Malibu wagon that has a TH350 C.
 

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For completeness, I want to add that while the TH350 in this thread is correctly identified as a TH350C with lockup converter, there IS another type of TH350 with an electrical connector. During the 1970s, GM used an early emission system called Transmission Controlled Spark (TCS). This system disabled the distributor vacuum advance in all gears except high gear (third in the case of the TH350). A trans from one of these vehicles will have a single wire electrical connector that was the signal from a pressure switch in the trans. This was used to operate a solenoid valve that controlled vacuum to the distributor. Again, not the trans in the original question, but another one to look out for.
 

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Discussion Starter · #6 ·
Is there anyway to get the plug from the junk yard and just send power to to it or tie wires together and confuse it to make it think its hooked up? I know nothing about this lockup junk. I drove it for the first time today and it definatly acts wierd and takes its sweet time shifting or whatever it was trying to do. I have another one when i get the money im gonna have it built im just trying to find a cheap fix to ride on till i can get the other one done.
 

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WFO
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Short_box said:
Is there anyway to get the plug from the junk yard and just send power to to it or tie wires together and confuse it to make it think its hooked up? I know nothing about this lockup junk. I drove it for the first time today and it definatly acts wierd and takes its sweet time shifting or whatever it was trying to do. I have another one when i get the money im gonna have it built im just trying to find a cheap fix to ride on till i can get the other one done.
You can hook up the detent cable correctly and make sure the modulator is hooked up to a manifold vacuum source and that the mod. is good.

If you do all that, the tranny will (if it's good in the first place) shift and drive exactly like any TH350 will- except the TC will slip a couple hundred RPM more than a stock TC would.

If the tranny is shifting weird or whatever w/all the proper adjustments and vac. line hook-ups, the tranny has probs.

The pressure switch for spark control was on the passenger side of the tranny (the TCC 2- or 4-prong connector is on the drivers side. Even though only two wires are used to control the lock-up) and is a single wired switch threaded into a pressure port near where the cooler lines are located- up towards the bell housing. In the case of this switch, you can remove and plug the port. I've heard of there being a temp sender in this area as well but have not actually seen such a thing yet.
 

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Discussion Starter · #9 ·
Thanks im gonna rock it as long as i can its just a weekend play toy for now hopefully it will last bout a month till i can gather the money to build another the way i want. Thanks again guys.
 

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Discussion Starter · #11 ·
I got ya.....oh well that sucks but atleast it is a used converter and i only picked it up for 25 bucks but still dont like throwing money away but plan to order a nice TCI converter when i build my new one. This is gonna come off retarded but is that why the rpms change so much goin down the road and shifts really soft and slow? Im dumb when it comes to a trans. Thanks again im learning alot and yall are alot of help with this.
 
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