Torque Converters??

I was checking out a low mile small block 727 that had been stashed away in the garage for probably around 20 years give or take. Found that it still had the original torque converter. This transmission is out of a 1985 Ram D-150. It is a non-lock up one. My plan is to use this in my Barracuda behind a 408, for now until I build a big block for the car. But anyways the sticker was still on the Torque converter and said low stall.

Anyone know what the stall speed would of been for this torque converter? I know behind a 408 it will be a little higher.

Now I have been starting to look more into Torque Converters and reading more post on the subject on here. The term "Flash Stall" has been coming up more often, why is this important? I'm guessing for a given torque converter it would be a little higher than the stall speed. But what does it mean?


Info on Engine Update:

Magnum block 408
eddy heads w/ valve job now have the same spring pressures
Crane 1.6 ratio rockers
Comp cams 20-604-9; Duration @ 0.050 lift 210 int./220 exh. 0.512 int./0.512 exh. lift, and lobe seperation 112, hydraulic roller
Hughes Air Gap
Headers

Right now the 408 has the Jeep's, fuel injection in place, and is going to keep the fuel injection when it goes in the Cuda.

I'm not sure on tire, depends what will fit and how much of a mini tube I can do with the Fastback. 28" tire probably.

This is going to be a nice daily drive (believe it or not the Jeep is the race car, lol), probably a 3.32 gear, not sure if I want to go to a 2.94 or a 3.55 yet. But it should have plenty of torque to turn even a 2.94. Before the rebuild, I ran a best of 13.391 with it in the Jeep with stock 3.73 gears, a 31" tire, all-time 4-wheel drive. Jeep weights over 4100lbs.

Probably somewhere around 1700-2200 RPM.

Low stall was around 1200-1400. If you don't have a huge cam in your 408 it'll make it stall a lot more than that. Not sure what to guess but 72 340 is probably close.

Flash stall is what the engine rpm "flashes" to when you nail the pedal at a low speed in high gear. Many things affect what a converter will flash to such as engine power, weight of car, gear ratio, traction

Don't build a 408 and then cheap out by using an untested unknown condition converter. That will only lead to disappointment. There's been several interesting threads about converters lately, it would be wise to do some more research.

BrianT said:

Don't build a 408 and then cheap out by using an untested unknown condition converter. That will only lead to disappointment. There's been several interesting threads about converters lately, it would be wise to do some more research.

Click to expand...

My grandfather had pulled the original drivetrain out of the 1985 Ram to put a 440 in the truck, he did this probably before I was born. I was born in 1987. The transmission didn't have many miles on it and it has been sitting in the garage tucked away in the corner ever since. So I am confident there isn't anything wrong with the Torque Converter or the transmission for that matter.

Once I get and build a Big Block for the Barracuda the 408 will be going back into the Jeep. The Jeep is awaiting to get re-done as well. But that is mostly just, paint, removing lift and rebuilding axles and such.

But everything will be getting re-used in other vehicles. Except for the Small Block 727 trans. Small block radiator and headers would go into the Duster. The 408 back into the Jeep. So pretty much the only thing that wouldn't be re-used is the Small Block 727.

So I don't want to spend to much money on the transmission. Just the stock torque converter and probably a shift kit. I'll save for a good torque converter for the Big Block.

That is the plan anyways.

I would never trust a tranny that sat that long as all it takes is a seal to bind,tear,or roll over and u have a rebuild on ur hands. That ls tork will not be enough verter for ur 408,but good luck 2 ya. Kim

BrianT said:

Don't build a 408 and then cheap out by using an untested unknown condition converter. That will only lead to disappointment. There's been several interesting threads about converters lately, it would be wise to do some more research.

Click to expand...

What he said!

If you haven't bought a transmission yet and are not going to put an overdrive in it, I strongly suggest you have John Cope build you a 904 and select a quality torque converter. It takes less power to drive, has a lower first gear and is lighter.

It would be money well spent and make a significant performance difference over a 20 year old transmission with a stock converter.

need more info.
gears,tire size and cam...are you racing this combo?
408 usually has lots of torque so a hi stall is likely unnecessary on the street

ir3333 said:

need more info.
gears,tire size and cam...are you racing this combo?
408 usually has lots of torque so a hi stall is likely unnecessary on the street

Click to expand...

Magnum block 408
eddy heads w/ valve job now have the same spring pressures
Crane 1.6 ratio rockers
Comp cams 20-604-9; Duration @ 0.050 lift 210 int./220 exh. 0.512 int./0.512 exh. lift, and lobe seperation 112, hydraulic roller
Hughes Air Gap
Headers

Right now the 408 has the Jeep's, fuel injection in place, and is going to keep the fuel injection when it goes in the Cuda.

I'm not sure on tire, depends what will fit and how much of a mini tube I can do with the Fastback. 28" tire probably.

This is going to be a nice daily drive (believe it or not the Jeep is the race car, lol), probably a 3.32 gear, not sure if I want to go to a 2.94 or a 3.55 yet. But it should have plenty of torque to turn even a 2.94. Before the rebuild, I ran a best of 13.391 with it in the Jeep with stock 3.73 gears, a 31" tire, all-time 4-wheel drive. Jeep weights over 4100lbs.

This might help with the idea:

John Kunkel:

OK, here is the factory stall speed specification for all 727 converters, direct from the '70 service manual:

Engine Diameter Engine RPM

225 10.75* 1450-1650
318 10.75* 1750-1950
340-4 10.75* 2250-2450
383-2 11.75 1850-2150
383-4 10.75* 2350-2650
440-4 11.75 2000-2300
426 2X4 10.75 2650-2850

Notice there are only two size converters, there was no high or low stall.
*The identical same part number converter is used on the 225, 318, 340, and the 383-4 but notice the difference in stall speed.
The stall speed of the converter rises with the power input, it's that simple.

And compression should be around 9.5:1.

jbc426 said:

If you haven't bought a transmission yet and are not going to put an overdrive in it, I strongly suggest you have John Cope build you a 904 and select a quality torque converter. It takes less power to drive, has a lower first gear and is lighter.

It would be money well spent and make a significant performance difference over a 20 year old transmission with a stock converter.

Click to expand...

I agree that John is real good with torqueflite's and a 904 will do the job for him more efficiently but I just want to point out that standard 904's do not have a lower first gear ratio. Only the later 999's (the 998's may also have it but that's not proven that I know of) have the lower gear ratios.

PoisonDart74 said:

This might help with the idea:

John Kunkel:

OK, here is the factory stall speed specification for all 727 converters, direct from the '70 service manual:

Engine Diameter Engine RPM

225 10.75* 1450-1650
318 10.75* 1750-1950
340-4 10.75* 2250-2450
383-2 11.75 1850-2150
383-4 10.75* 2350-2650
440-4 11.75 2000-2300
426 2X4 10.75 2650-2850

Notice there are only two size converters, there was no high or low stall.
*The identical same part number converter is used on the 225, 318, 340, and the 383-4 but notice the difference in stall speed.
The stall speed of the converter rises with the power input, it's that simple.

Click to expand...

I have actually seen a factory converter stamped with "low stall" but it came out of a later 70's trans so maybe later on they made different versions

I have a 904 converter right now that says "high stall" on a factory pink sticker. I've also had the ones that say "low stall". trust me, there is a difference