318-360 lock up torque converter swap

Bronze Barracuda said

I have a lock up torque converter from my 627727 that was behind a 318. I was planning on using a torque converter from a 360 that I have..
I thought the torque converter from the 360 was a lock up as well but it is not.
I'm using the transmission from the 318 for the 360. I know the 318 TC's won't work unless you add the weight from the 360 TC. Or get a B&M flex plate. Since this is a budget build I was planning on welding the weight into it, but two questions come up, where do you weld it and does the weight of the weld play into the final result. Also heard that you shouldn't weld the weight onto a lock up TC as the heat will destroy it?
Any thoughts? Greatly appreciated.

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It matters a LOT where it is welded on and what size it is- that's how it balances!
Take careful measurements where the weight is located on the 360 convertor, in relation to the offset convertor lug. Measure and mark the lockup convertor in the EXACT same spot.
Then carefully grind the tack welds off the weight onto the 360 convertor, being careful not to alter the size or shape of the weight itself. Then tack weld the weight in the same way on the lockup convertor- no need for full welds, a couple of solid tacks like the factory did is plenty. You're done.
Alternately, if you're not comfortable cutting the welds off on the 360 convertor, shape an identical thickness piece of metal to the exact same size and shape as the 360 weight and tack that on.
You won't destroy the lockup by welding the weight on (the factory did, after all) unless you get carried away and start blowing holes in it.