What do I need to know about Torque Convertors?

Do they wear out?
How can I tell if one should be replaced?

I currently run the original torque convertor and turbo 350 on my '81 T/A, but I have upped the motor to a healthy 73-400. Seems a bit sluggish however, and I have never done any other work to the drivetrain (..still running 3.08 gears)

I do have the B&M Shift kit ready to install, but some have reported that this is not necessary.

Should I just get a new convertor after 24 years, or focus on tranny rebuild?

Thanks

TQ Conv. RELIABILITY
Factory converters fail, particularly in cold-Canada. Dominant failure mode is the steel Sprag race strips-out of the aluminum stator...as they are a fine-tooth press-fit that gets sloppy at hot temperature. Indication of failure is sluggish pull-away.

Race converters have a better engineered stator//sprag spline engagement.
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TQ Conv. PERFORMANCE
stall speed represents the RPM that the CONVERTER stops Torque multiplying (slipping) and starts working as a fluid-coupling (clutch).

HIS

Is it the orignal 81 lockup TH350? Mine had a very tight stock convertor. Contiental made a looser one for me all the difference in the world, good price , at my door in 2 days!

It is the original turbo 350 that came with the '81 4.9L Turbo engine.

I read somewhere the turbo 350's that came with the 4.9L turbo engines were a "heavy-duty" version to handle the increased torque load of the turbo-charged engines.

The car will just break loose from a stop (3.08 gears) and a bit of "chirp" is normal on the 1st to 2nd shift, but at top end, the engine seems like a lot of power is not getting to the pavement.

I read somewhere else that low top end was an indicator of a poor torque convertor.

But how can you really tell, other than replacing it?