What is the procedure to check the stall speed of a converter?

How to figure out "flash"

Thank you in advance

To tell where the convertor hits/ flashes at, I put the car in high gear, and at a slow roll stab the pedal hard, watch the tach.

I agree... that's the easiest way to do it. It MIGHT very quickly pass that number on a hard launch, but it will settle back into the number you see on the tach like Don says.

Good way to see where you're at without a data logger or a playback tach.

My favorite way is to point a video camera at the tachometer and watch it in slow motion but you can also do it the way these guys suggested, just don't do it too long or too often as it is not very good for the converter, my 8" ATI actually said not to do that in the instructions but we all do it.

that might work for a manual valve body.
i would think tranny guys have better ideas.

Check the rpm it falls back to on the shift.
Doug

Make sure your fluid temperature is up, or the results won't be consistent with actual use.

I found that the tach fooled me when I tried to stall it in high gear, or against the trans brake. I didn't have traction anywhere but on the track, and tach needle momentum sent the needle too high when revving against the transbrake. You won't have accurate info though IMHO unless you have a video , playback tach, or a data logger.

Here's a fairly good demo of the 8" converter in my car. Approx 5200? stall but flashes to around 5800-6000 on a pass. I come off the 2 step at 3000. Shift light is set at 7200 and you see I'm shifting with the light not really reacting to it....I still shift by ear and seat of the pants, lol

https://youtu.be/PjXcf95e6v0

Sorry this us kind of off the OP's topic but good info from some known names in the convertor industry. And I thought it was a good read if you guys have a couple minutes take a look in this thread it cleared up some misleading thoughts I had about how convertors work.
http://www.yellowbullet.com/forum/showthread.php?t=1159754

All that really matters is where it puts your engine speed going down the track. The question is whether there's any home test that's useful. I doubt it, you just can't simulate accelerating the car.

So my delay box has an rpm playback feature that shows the motor at 5600 rpm at launch, but it shows dropping to 6000 rpm after shift. You are saying that the 6000 number is the actual stall speed? jim

Everybody has their own idea of what "stall" is. To me it is the RPM that you see on the tach when you floor it at the starting line.

Wow! For decades I understood it to be: From a dead stop apply left foot braking HARD. Then mash the gas, without the car moving (or minimally if the brakes cant hold it) that's your stall.

and yea, its hard on the vert. Fluid builds heat FAST and you risk ballooning the verter if you over do it.

I LOVE reading stuff like this and always save the link so I can re-read it several times to let the info have time to sink in my hard head. LOL Converter stall can make or break a good combo.

The "stall" speed is a K factor rating(math).. the "flash"
is what you see at the hit of the pedal(max load/rpm)...
as some said.. its hard to get a true readings.. the drop
back or the high gear or on the trans brake with no chip..
I like the trans brake way.. BUT you have to have the trans
brake.. the drop back method is pretty decent but you dont
see the multiplier in the conv but you still see max rpm

My car goes to 6,500 on the trans. brake, on the stands. Racepak shows 6,100 like clockwork coming off the stop in high gear. I never tried getting a Racepak reading on the stands. I did check the Mega 400 and it agreed with the tach. Racepak and Mega 400 have been pretty identical in recent playbacks.