72 sb 30thou over, 186 small valve heads, howards retro hyd roller 272/278 .510/.525, with 3.08 rear, 700r4 and 2800 lockup converter.
build for cruising not a racer...
stall was chosen by engine builder, cam 111145-12 has a range of 1,500-5,600

how do i know if i have the right stall, the vette feels like it revs and goes nowhere...
reversing up a steep driveway, motor screaming, hardly moving..
cruising along in 4th and locked up, put boot into it, lockup disengages, but revs jump high before anything seems to happen..

is my stall speed to high?
should i be looking at getting a lower one, say 2200-2400 ish?
are the smaller diameter better? have stock size diameter atm.
will a lower stall help mileage also?

 

With your mild camshaft and high gears the stock 1300-1400 rpm TH700R4 converter was all it needed. Buying a 2800 rpm converter was a huge mistake as you have found out.....................

 

is the converter stalling at 2800 as you were told.
If you apply the brakes and slowly come up on the throttle while holding the brakes how high do the RPM's rise before the tires overpower the brakes?
Or if you stop on the road and then mash the throttle, how high do the RPM's rise before the tires spin? Best done on grooved concrete for good traction.

2800 stall should not have a huge effect on the RPMS in reverse. If your cruising RPM's are 1800 and you unlock the converter by mashing the throttle then expect it to rise to around 2800.
It sounds more like from your description that you may need a TV cable adjustment and the clutches are slipping due to lack of pressure. If this is the case, do not let it persist as it will damage/overheat/prematurely wear the clutches in the transmission.

 

bought carb bracket and bits n pieces from BTO, and set it up using there procedure.
also installed there pressure gage for setting the line pressure.
as soon as the throttle lever is moved slightly, the line pressure increases.
last time i checked oil, it looked clean and didnt smell burnt.

 

It sounds like you did the set-up properly for the TV cable. I would check the stall of the converter then.
I have a 2600 stall converter and it does not rev excessively at low speeds or otherwise.

 

Not very helpful.

 

As said figure out what your current converter is stalling at. Footbrake it and bring up the rpm until it wants to push thru. Buying another at a few hundred rpm lower is not a big change and chances are something is not working right. You didn't say what brand your stall is, I've had bad cheap converters before that slip too much, but not as bad as you describe. Is your exhaust really loud? Are you sure the fluid level is correct? Does it always act like it or only when hot?

 

would be the std GM stall that came with the trans when i got it, not sure what car it was out of.
trans was gone thru n rebuilt, then they tweeked the converter.

will try n do a brake test later during the week and check the stall rpm

 

It's a possibility that you have slipping tranny clutches. The TV cable transmissions are very sensitive to getting adequate TV pressure when under high torque conditions (WOT). If TV cable was set 'low', total clutch pressure would also have been low and slipping could occur.

Once a clutch starts slipping, it will never get better. Clutch facing material wears off quickly; then there isn't any friction material left to grab the other plates.

Hope I'm wrong. But, that's the only reason I can think of that would cause 'slipping' at high rpms.

P.S. If you weren't going to be racing your car, there was no reason to install a 2800 rpm stall unit on the transmission. So, that might not be helpful...but it certainly is factual.

 

Stall refers to what it flashes at and the only way to really know is using a trans break. It does not mean the converter makes an engine rev to a specific RPM for normal driving. And a 2800 stall with that motor is unlikely to happen because torque and power impacts the out come of a stall converter.

Just because it says 2800 do not expect that speed in every motor combination.

If your slipping your slipping and have a issue other then the stall converter.

 

Rookie input: My 700/R4 T.V cable had a VERY SMALL "window" of adjustment between slipping and grabbing harshly between ALL GEARS, and when downshifting upon hard acceleration.

It took me a day of road-testing to reach a compromise.....I finally was able to adjust-out the slipping problem, but there was a small jolt-- enough to "bark the tires" with heavy throttle from 1st to second gear. All shifts are SOLID/NOT SOFT under normal acceleration.

Two years later all is well.....still barking the tires from 1st to 2nd.....but NO MORE SLIPPING.

(1992 350 cu.in/very mild cam/headers/Holley 600CFM/Standard torque converter 1800 stall, I think).

 

Let us know the result of standing on the brakes hard and then stepping into the gas to see the rpm reached before the car moves.

Most transmission shops use an exchange service with a converter rebuilder. I have a "higher stall" converter from one of these shops in my Impala. It was a $100 converter so it was cheap, but it's sloppy and hardly has any drive until a little over 2000rpm. But, it's still not as bad as you describe.

A quality aftermarket higher stall converter would work better than both yours and mine. The pedal position vs converter slip is more linear in a better converter.

It's impossible to know the stall speed of the stock converter from the transmission without knowing the application. Even with knowing the application it could be difficult to figure out. It could have been anywhere in the 1100-2000rpm range. If you still have it and the transmission didn't experience and damage with that converter installed then you could try it. If the transmission shop kept it then it's likely long gone.

If the test shows you don't get any movement until over 2800rpm then you could try to get the shop to swap the converter for you. You may get them to exchange it for free so you can just pull the transmission back and swap the converter.

 

I would not agree with this statement. A higher stall converter allows the engine to be in it's operating range according to the cam specs for better performance when the converter stalls or essentially starts turning one to on with the crank minus any slip.
It also allows a larger overlap cam to idle freely without having to fight the torque converter engagement while not moving. Having a low or stock stall converter on an aftermarket cam that has less cylinder pressure at idle but greater performance higher up the RPM range makes it very hard to tune for idling in gear while not moving.
To compensate you end up jacking the idle up so high that when it's not in gear it may be 1000 plus RPM, then you get a run on problem at shut down.
Stall converters are not just for racing. One needs to understand the impact of at what RPM a converter stalls and the engine specs to understand the proper application of a stall converter.

If your cam has an operating range of 2000 to 6000 RPM then why would you have a stock 1600 RPM stall converter making the engine struggle all the way up to at least 2000 RPM?
In that scenario I would probably use at least a 2600 to 2800 stall converter.
Understand that the stall converter can and will stall at a lower RPM under less load.
It's stall is also a function of engine torque. More toque=higher stall, lower torque=lower stall.

 

with the above. This sums it up. The cam needs a stall at least around the 2000rpm range to hit into the powerband fast when you get on the gas.


You're still posting wrong info I see. A 1300-1400 stall rpm converter will be a dog off the line with his cam.

 

You guys just made my point. You don't need a high stall converter unless you're racing the car. Why would I need to be in the "power band" to take off from the stoplight when I'm picking up bread & eggs at the market? The only reason to be in the power band at take-off is for 'hot' starts!

If you don't race the car, you're just wasting a bunch of fuel having the engine run in the "power band" all the time.

 

A good converter will drive away with little throttle input without having to first reach the stall rpm. And just how much fuel does the engine "save" when it's run below it's powerband where it's very inefficient?

Even my crappy converter will accelerate below 2000rpm with little throttle. It just jumps to a higher rpm rather quickly as I get into the throttle compared to what a better quality converter would do.

 

A high stall converter differs from a stock converter in the sense that the rpm is raised at which the internal converter components- the impeller, the stator and the turbine start to turn together, and hence, stop the torque multiplication phase and begin the coupling phase.

My 4000 stall drives like a normal converter until I punch it , at that point all that is delayed is the point of coupling , add to that the converter makes a huge difference once I am at full throttle by keeping the RPM DROP at shift points much lower allowing me to maintain power through each gear change , ( ex ) I shift at heavy throttle I may lose a few hundred rpm keeping my engine in the power band. A lower stall would allow my motor to be pulled out of its power band forcing it to recover the lost RPM at each shift.

IT DOES not effect daily driving or cause a you to rev high to get moving lol

 

I agreeThe trick is to buy a good converter like your ptc.The fluid coupling is very efficient along with the the higher stall speed to get the best results.Torque conveters have come a long ways from the days of people using the vega units.
To the op I would call kenny at Ptc and get a professional opinion.He can set you up with a unit that will hold the power and function the way you want.There are also other top notch units out there and you'll have to decide which way you want to go.
Good luck

 

LOL! someone needs to do their homework on the purpose of a higher stall converter.
I guess if we're talking about "need", a corvette doesn't need 8 cylinders to run, or need 350 HP, or needed at all for that matter.

Plenty of Toyota's, Nissan's, Mazda's etc. to get bread and eggs with.

A Corvette is a performance oriented car. Let it be what it is. Mods for more performance are quite common. So is a higher stall torque converter.

 

Anybody who REALLY knows anything about torque converters is well aware that a higher stall ratio converter is LESS EFFICIENT at lower rpms than one with a lower stall speed. Yes, a high stall speed converter will take off at much lower rpms than the stall speed. But, it will take off at higher rpms than an identical vehicle with a lower stall speed converter.

As all C3'ers know, in town it's the take-offs that eat the fuel up. That's why we get 10-12 mpg in town and 15-17 (or so) on the highway.

If you do much driving in town with a high stall speed converter, you WILL get significantly lower fuel mileage than with a stock (1400-1600 rpm) converter.