Questions on stall converter?

[Bugflipper]

Okay fellows I have a cam recomendation thread going and that has me wondering about stall speed. I do not want to rev up to a given rpm and launch a car. Just a normal take off, letting off the brake and stabbing the throttle if so inclined. I understand a higher stall can prevent the car from being so hard to hold at a stoplight. Are those the only two uses of a higher stall converter? I have disc brakes on both buckets and wider front tires than normal to aid in making the discs useful. Holding the cars back at a stop isn't a chore. Just takes more effort than power brakes would. Is there something else I'm missing here on the benefits of a smaller toque converter? I don't intend to go to the dragstrip so I don't see the need. Also with big drag radials it looks like those little 10 bolt rears that are so popular would be stressed to their max with a 3000 rpm launch.
Thanks.

 

[RPM]

I think you said you were going to use the 700r4 trans. When we use that trans we used a converter from an S-10 4cyl truck. Behind a v-8 it would stall at about 2500, but still lock up in 4th gear. A stall converter does not mean that the car won't move till the stall speed is reached. It just means that the engine can be flashed to about that RPM to help get the car moving and yes it is a lot easier to hold the car at a light. Releasing the brake pedal at a light and car will begin to creep just like any other converter.

 

[Screaming Metal]

Ron Pretty well summed it up! Also, when in heavy traffic, your motor won't be pulling so hard against the brakes, so if your in heavy stop and go traffic....your brake leg won't get such a workout. Also makes for smoother acceleration, if running a 'peaky' motor. When running a convertor, add a cooler to offset the heat made.

 

[Joe-405]

Both of these guys nailed it................. But make sure to buy the cam first then the converter if possible and dont buy a really small diameter one for the street either.

 

[Neshkoro]

So, as it goes, the higher the stall speed the more RPM the engine needs to be at before the converter and the engine hook up?

 

[Mike]

So, as it goes, the higher the stall speed the more RPM the engine needs to be at before the converter and the engine hook up?

That's close.

A regular converter never fully 'hooks up', because it is a lot like using one fan to blow air across the blades of a second fan, to make it turn. Stall speed is really theoretic, because there are different parameters that will come into play, together, to determine stall speed. Torque produced by the engine, weight of the vehicle, gear rations, brake condition, etc.

A converter that couples at 3,000 RPM in a big-block Impala will never get that high in a Nova with a 327, for instance.

 

[Golly]

Yep I agree with all that info so far, plus you can get away with a high stall in a Bucket because they're so light. you'd barely know it was there, untill you step hard on the gas. I run a 3000 in my Model A truck, with a big cooler and it's nothing but FUN, plus it will idle in gear when the motors still cold, , and doesn't try to drive thru the brakes at stoplights,

 

[retired49]

,last year i had problems at stop signs with the large cam, so i put a 3600 rev max stall in this year and stroked my 429 to a 545 cu.in. it idles perfect and launches hard i have 31x18.5 x 15 pro sportsman tires 3:23 gears in a 10 bolt posi rear end and c-6 trans,,,,but i am having a ptoblem running warm i do not know if it is the stall or because i had to bore 30 over for the stroker kit. Its probably a combination of both. But the stall will bring your engine to life and make it much easier to drive

 

[Joe-405]

,last year i had problems at stop signs with the large cam, so i put a 3600 rev max stall in this year and stroked my 429 to a 545 cu.in. it idles perfect and launches hard i have 31x18.5 x 15 pro sportsman tires 3:23 gears in a 10 bolt posi rear end and c-6 trans,,,,but i am having a ptoblem running warm i do not know if it is the stall or because i had to bore 30 over for the stroker kit. Its probably a combination of both. But the stall will bring your engine to life and make it much easier to drive

Is the engine or transmission running warm ?

 

[Mike J]

,last year i had problems at stop signs with the large cam, so i put a 3600 rev max stall in this year and stroked my 429 to a 545 cu.in. it idles perfect and launches hard i have 31x18.5 x 15 pro sportsman tires 3:23 gears in a 10 bolt posi rear end and c-6 trans,,,,but i am having a ptoblem running warm i do not know if it is the stall or because i had to bore 30 over for the stroker kit. Its probably a combination of both. But the stall will bring your engine to life and make it much easier to drive

If its the engine you might need a larger rad with more capacity, or maybe slow the pump down w/ a larger pulley or try a restrictor (temporarily) instead of a thermostat to determine if slowing down the flow will help. IMO.

 

[Screaming Metal]

What Mike J. said....with a big inch stroker motor, the timing will cause you to be on the warm side, be sure and check it.
Another thing, the torque of the motor will affect your stall speeds....

 

[PotvinGuy]

If you're not having any problem holding it at a stop, then you are OK. A higher stall means the TC is slipping more. Slipping is not a good thing, but a necessary thing with an automatic tranny. GM made a 350c tranny/TC combo in the 80's and it could lock up, but they are hard to find and supposedly weaker than an ordinary 350.

FYI, stall speed is the speed the motor/TC would reach at WOT and the output shaft held. So it is dependent on the motor's torque, and the ratings given by the manufacturers are just guidelines based on some "typical" motor, maybe a stock SBC.

My first bucket came with a big TC, about 12" diameter, and I had to stand on the brakes. Swapped in a B&M Holeshot 2800 and life is good.