launching with high stall converter

[b5blueaar]

Specs: 1974 cuda, 440 engine, 727 trans, comp cams extreme energy cam, .525 lift, 241/237 duration at .050, 3:91 sure grip
I put in a TCI converter with 3500 rmp stall.
I wanted to be able to rev to 3400-3500 to launch with brakes holding the car.

At 2800 rmp, the car will move forward. It seems to me, the torque converter is already locked, since you cant hold the car with any higher rpm.

What am I missing here?
Why cant I get above 2800 rmp without creeping or spinning the tires?
Why is the torque converter delivering power at only 2800 rpm?

Any suggestions would be appreciated.

My old torque converter had a 2500 rpm stall and I could launch at almost 2800 with it?

thanks

[Chryco Psycho]

Either the converter was not made correctly & it is stalling at too low RPM or the engine is not making the torque that the converter was rated to stall at

[gomangoRT/SE]

I dont race anymore but I have a couple of guys who tell me if you want a true stall speed of 3000 then get a 3500 stall............if you want a true 2400 stall then buy a 3000.   They seem to think the manufacturers fudge on the stall numbers............I am only repeating what I hear them say.    I honestly dont know.

[Grancoupe]

I have about the same setup only with a 383, so I'm not turning as much torque. The company that was recommended to me was a local shop to my area, but the guy has been truthfully doing this stuff since the 50's. I went over the setup before and after the unit was built. He had explained the definitions relating to converter stall is. The "stall" is what the converter with slip to at a stand still without overcoming the brakes and is generally about 800 to a 1000 RPM lower than the flash. The "flash" figure of a converter is what the converter will stall to when you floor it and really load up the tranny. It should jump quite a bit. If your not getting a solid hit it might mean the there is a problem with the settup. Each of these fetures of a converter can be set individually within a range, but can be fine tunned if the tranny guys gets into the converter.

Is the motor bogging down when you floor it or are you just trying to get the motor up that high on the launch?

[b5blueaar]

thanks, I have not understood converters and stall speed very well. Maybe it is working the way it is susposed to?
Maybe my brakes are weak also so it creeps earlier than if the brakes were good?

grancoupe: No, there is no hesitation and no bog at launch. It just screams. In fact, I cant really floor it off the line or it will lite up the tires, so I have to kinda ease into it until about 60 ft.
I just wanted to be able to launch at a higher rpm and use racing slicks for more traction and more jump off the line.

Next time I race I will have to notice what rpm it seems to go to when I floor it.
But I have to rebuild the lower end first, seems we fried a crank bearing.

[Grancoupe]

grancoupe: No, there is no hesitation and no bog at launch. It just screams. In fact, I cant really floor it off the line or it will lite up the tires, so I have to kinda ease into it until about 60 ft.
I just wanted to be able to launch at a higher rpm and use racing slicks for more traction and more jump off the line.


Your already going down a bad road. You fried a crank? And you still want to launch even higher and harder? You said yourself that you really can't get into it or you'll light the tires. See what you get for 60 ft times with the slicks, then decide if you need to torture it even more.

Think about this. I've watched quite a few hot race cars loose miserably on the street. Been part of a few on the street side myself. Not sure if you intend on playing on the streets but if you are, the more radical the more that can go wrong.

[b5blueaar]

yeah, good points.
slicks would be an easy way to launch faster.
We play on the street all the time.
Your right again, lots of parts have broke.
but thats 1/2 the fun, trying new things to get a little faster.
Im going to up the compression to 10:1 when I do the crank and pistons this winter for a little more power, but for the street its got plenty now.

[Grancoupe]

im running 10.25 to 1 and it can get a little touchy when I try to run the car when its hot out. 90 degrees and above. This is on pump gas of course. If I had to do it all over I would have opted for a little less. All the same, good luck with it...