I have a 383 with a TH400 in it with a 23-2500 stall Torque Converter. Cruising around town the power and feels like a snowmobile and shift points are hardly felt unless I’m really getting into the gas. I know how TC’s work, I’m just wondering if I should’ve stuck with the stock converter. I hear that higher TC’s generate more heat and heat is an enemy to the tranny. I don’t drive a whole lot around town, just a little on the weekends and mostly freeway driving. I’d like to hear some of your experiences and opinions.

 

Add a trans cooler.

 

I guess I should’ve clarified that I don’t really like the snowmobile feel. I’d rather feel the shifts but the engine manufacturer recommended this TC.

but yes, I’ll consider a tranny cooler. Any ideas which one that fits a 74?

 

I'm no expert, but I'm in the in process of installing a 4L60E rated to 450 hp and tq. Silver Sport Transmissions is the supplier and that unit comes with a 1600-2000 stall converter. Meanwhile, I'm considering the Smeding 383 Cruiser rated 380 hp, 440 tq. They recommend a 2000-2200 stall converter. I asked Smeding about the 1600-2000 that will come with my tranny. They said it would be fine as long as I have at least a 3.31 rear end. I have a 3.54. Also, going onto TCI's site they have a stall guide with a key item being cam duration. They list for cams 260 to 265 duration stalls up to 2000. More goes into it, than that, but it suggests for spirited street driving you may be too high.

As for what was in a '74 stock, good luck getting an actual number. I've been trying to figure out what was stock in my 80 L82 which should be a higher stall than the L48 given peak tq is 1000 RPM higher. But I can find no actual spec for it. Even on the TC which I've pulled, there are no markings which I can find which ID what it is and thus track down the stall. All it has on it is a TB7 that looks painted on, a stamped "CANADA" and a stamped "G03". I can find nothing that ID's the TB7 or G03 with a TC.

I do know that my cousin's '74 350 CI, TH400 tranny was crisp off the line and shifted well. It was the first car I ever drove any distance on the road. Got my permit a few months later . 4 years later I drove it from NY to Las Vegas to deliver it to him after he moved. At night, t-tops off, cruising the Vegas strip, the reflection of the casino lights just flowing like water over the curves of a C3 . Those were the days.

Good luck,

 

Add a shift kit. Depending on which one or level you get, your tires will chirp when you shift gears.

 

The torque converter is not what produces 'shift' quality. It only transfers torque from the engine to the input shaft of the transmission. Shift quality is dependent on the vacuum modulator schedule, the shift valve springs and several other hardware factors in the trans valve body.

If you wish 'firmer' shifts, you would do best to install a "shift kit", as suggested above. I don't think that is needed, but if you prefer to feel all of the shifts made, so be it.

The 23-2500 rpm stall speed on the converter just means that when you are at a dead stop with brakes applied, in one of the forward ranges, and with accelerator pedal at WOT, the engine's rpm should be in that 23-2500 rpm bandwidth (if the converter was properly selected based on your engine's torque capability).

 

Shift kit what you need for firmer shift .... I’ve been running a 5000 rpm stall on street ( not my Vette ) since 1999 and have never had a “ over heat issue “ with it and on a normal drive you would never know it has a 5K stall Converter in it unless I punched it while you were watching the tachometer , over blown hype on high stall converters

 

I do have a shift kit. I’m still breaking in the motor so I haven’t taken the motor to high revs yet.

 

my cam is 220-224/540. It has a shift kit installed when I had the transmission rebuilt. When I had the stock motor/ tranny setup it did shift normal. I guess I’ll take it to my transmission guy and see what he thinks. He was questioning the torque converter choice when I told him what the engine manufacturer was recommending. The rear end is 3.08

 

If you have a quality built trans with higher stage shift kits you will have bang hard shifts even at part throttle. Just idling down the street it will bang every gear. There are many "Transmission guys" that don't know about or understand performance transmissions or performance TC's.

I'm a firm believer in you get what you pay for. Very efficient high stall converters don't even need the lockup function in modern lockup trannies. If you buy cheap crap you get what you paid for including the mind set that high stall means excessive heat. you bought junk. I used to have a dragster with a 6500 stall and at the end of the 1/4 mile after slowing down from 180 mph you took the return road and just drove back to your pits and then again up to the staging lanes. Massive stall doesn't mean that it doesn't drive well if you spend the money

 

that’s quite possible as Ilive in an area that doesn’t have many reputable performance shops. Perhaps I’ll have to drive it down to Los Angeles to someone who knows something. I know almost nothing about transmissions so I’m not surprised that I may have been duped. I’m not happy with the performance of the transmission at all so it may be back to the drawing board....

 

I assumed that someone who has a 23-2500 rpm stall speed for his converter wasn't really using it as a high-end drag vehicle. More like someone who is wanting to 'dabble' in the speed/racing game. If he wants to feel harsh shifts every time....so be it.

 

when I shift it manually, it does shift nice and firm. Just seems like it shifts premature when it’s in the normal automatic mode. I’m taking it to a transmission shop on Tuesday to see if they can improve it. If not, probably swap the TC for a better higher quality one.

 

What kind of modulator do you have? Is it adjustable or stock/non adjustable? The modulator will determine shift points and feel.

 

Agree with Mrvettenick that the TC does not affect shift points, that is the job of the vacuum modulator. Get an adjustable unit and start making minor changes to suit your desires. Keep in mind that part throttle and WOT are different characteristics for a transmission. Seems like you might want to experiment with a manual valve body. It only shifts when you shift it. Gets annoying on the street once the new factor wears off.

 

Not a TC problem. The governor controls the shift points. (The modulator to a lesser degree, maybe 100-200 rpms at most). With the correct set of springs/weights it can be set to shift at your desired rpm.......takes some time and error, but a good trans shop can hit it correctly the first time. Part throttle still remains OK, but as you rev it, WOT will be as you have set it. Mine was set to shift at 6500 rpm at WOT while in "drive". I could still manually shift also if dsesired.

 

Yes, but the poster is inquiring about not feeling the shifts. Not the shift points.

 

Loose converters soften shifts considerably.......even with a shift kit you may not feel them putting around. It is the nature of the beast but the thing that gets me is that it is usually a 3000 converter that has these traits......but you may be at that stall now, and I will explain.....
The mentioned trans cooler is mandatory with any kind of loose converter, and is good practice.....especially in hot climates.
When you take it to the trans shop, have them check the hose for the vacuum modulator and the modulator itself.
The converter is like a hydraulic slipper clutch......the harder it has to work, the higher the stall will be. You have a 3.08 gear......the converter will have to "load" harder against that gear to move the car, which increases stall speed.......this also is the case with an engine that makes more torque or a heavier car.
I like mild stall converters because it gets rid of the "lurch' in gear at idle.......I don't like snappy shifts myself either, if the trans bangs into gear everytime, it is hard on components.....
But it is your car!

Jebby

 

In my LS swapped C10 I'm running 3000 stall Yank converter and you can feel all the gears shifts. I have used both Yank and Circle any where from 2800 -3600 stall. All shifted like a stock stall until you put the pedal to the metal. They not cheap but they work well. As I understand the cheap stall converters are reworked stockers with various results.

 

Jebby, thanks for your input! I may have a loose converter but your explanation of the combination of the 3.08 diff, the high torque of the motor might magnify the issue. I’ve submitted my specs to a couple different transmission shops as well as TC manufacturers to see what they tell me. There could be multiple issues and one could fix the other. I’ll get the shift modulator checked first as well as the TC. Make sure there’s no slop and everything is right. Then I’ll go after the TC and see if that helps the condition.

to tell you the truth, I was a little disappointed at the overall performance. I wasn’t expecting a breakneck dragster but The motor seems to be carrying a load like it’s starting out in 2nd or 3rd gear. I appreciate everyone’s input and I’ll send updates hopefully as soon as Tuesday