Don Terrill’s Speed-Talk

Can I flush my turbo 350 converter with out taking it some where?

Yes!
Drill a 1/8" hole in the bottom & let the fluid drain. If you want to flush the system, put a temporary plug in the hole & refill.
Once you are finished flushing, fill the hole with a 1/8" pop rivet, smeared with silicon.

Or you can just do it how we do out here in the woods, put it upside down with a water hose sprayer set on kill and let it eat. Turn it over a couple times and fill with tractor supply solvent and repeat.

Where on the bottom of the converter? Doesn't it have like 150 lbs. pressure run thru it ? I keep spraying brake cleaner in it then dump. Has a little water in some how. I know because the 1st time cleaning it came out strawberry shake color. A pop rivet would really not leak? Should I put JB weld under the rivet?

Personally, I wouldn't use a rivet, although you can use a closed end rivet. Fords have a small boss welded on their converters with an 1/8" pipe plug for draining. I'd do something like that before a rivet, especially on a high rpm race car. Weld a washer opposite of the plug if you're worried about a balance issue.

You'll never get all of the oil out of a converter without a drain plug. I used to rebuild torque converters, so I kinda know.

Chrysler also used drain plugs. Pathetic that GM didn't it....

I recently bought a New TCI converter that came with a drain plug. Was kinda surprised since I never seen one before but they put it on the outer back towards the outside, looked like 1/8 npt if I rem right. Imagine they did it that way so it could be drained in the car.

Be aware that drilling and adding a pipe plug may alter the balance and cause unwanted vibrations.

Prob a good idea to use an aluminum hollow plug, idk what TCI used but I'll assume it's balanced.

1/8" NPT. That is what Chrysler used for years, don't know if they still do.

If you're really worried about balancing, put the pipe plug equally between two converter bolts and use a similar weight washer on the converter bolt opposite the plug. (Assuming your converter has 3 mounting lugs).

Maybe is am wrong, but I wouldn’t think balancing would be a problem. I would have expected it to balance like a fluid damper or a tire filled with flat proof.

We always used an aluminum 1/8" pipe plug in the drain hole. Weighs nothing.