Thread: Simply, What torque converter?

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So I've done the rear, asked questions to you all about radiators (by the way, just bought an aluminum crossflow, I've gotta post some pics, looks great).

Now I'm doing the trans. Gonna take out the TH350 and go w/700r4. By spring, I should have a new 383GM crate also. I know, I have asked also about big block conversions, but I've decided on the 383 route. So, here's the question:::

I still have the 283 which is mildly modified. I have 3.70's in the rear. I just dont get this whole stall speed thing? I have read over and over, but not getting it. I want to get this 700r in and be able to come out of the hole nice, you know, leave some BF goodie on the street. As it is now, its a dog. Even if I try to power brake, it just cannot come up in rpms, just seems to bog. Now when I hit about 2000rpms, car starts to sound awesome-and move too. I'd say my power band is about 1800-4500. Does this mean if I get a converter with a stall of say 1800-2200 that the car will not move until this rpm??? And if so, does it just grab or lock like popping a clutch??? Just need a simple explanation. If I can get a little better out of the hole, I may keep engine longer. It runs so good.

Oh, and will I be able to ust the same for the 383. Thanks all.

If the engine responds quickly to throttle when coming off-idle, you may want to try 'flashing' the converter.

That'll give you a harder hit (locks at a higher rpm) than it would if you did the power-brake bit.

Higher stall converters are like a stick shift/clutch setup to an extent.
Similar to spinning the engine up then dumping the clutch.

There are compromises though.
Get a converter with too high a stall rpm and it won't lock up when cruising the highways and will generate heat - to an excess if a too-high stall is chosen.

Bigger - read more torque - engines will stall a converter at a higher rpm than will a smaller engine that develops less torque.

Running in overdrive with the 700 trans will probably result in a 2400 rpm stall converter slipping at highway speeds . . . at least it will be that way until you exceed the speed limit.

MPH = tire diameter x RPM divided by axle ratio x 336

Running in overdrive will drop the rpm about 30% so it's doubtful you'd have full lockup at normal highway speeds.

The car will move at idle rpm levels with a 2200 rpm converter - like when you're maneuvering in a parking lot - and sometimes you have to ease a little throttle in to get where you want to go.
This depends to an extent on rear axle ratio as well as trans low gear ratio as well as how heavy the car is, but as a general rule, idle rpms will move the car on level pavement quite well.

Phil,
Rather than a ho-hum description - this outfit has a pretty good description of an aftermarket unit. I'm not advocating the use their product, I use another company, but these folks have a better write up.

http://www.protorque.com/techi/ti_al.htm

C9,
I think I understand. With the th350 now, at highway 55-60, Im taching about 2800-2900. Tires are 28".
What if the 700 has this lock-up feature?

Running in overdrive with the 700 trans will probably result in a 2400 rpm stall converter slipping at highway speeds . . . at least it will be that way until you exceed the speed limit.

Running a 700-R4 without a lockup provision is playing Russian Roulette with your trans and your $$$$ - even with a stock torque converter. That's why all of the stock installations have lockup. There are simple kits available.

http://www.bowtieoverdrives.com