57 chevy, Ramjet 350 crate,700R4,pwr front discs, 7-800 RPM idle. Must hold moderate brake pressure to prevent the car from rear -ending the guy in front. 2500 stall, brakes work good. Wifey's leg gets sore. If she ain't happy.......
I'm scratching my head here. If the '57 has an idle speed of 700 or 800, why the need for a 2500 stall converter? Maybe I'm missing something here. I've missed a lot, over the years.
To allow the engine to come up better into it's power band. This is especially important with a hotter cam. Kinda like slipping the clutch on a stick shift to allow the revs to come up to where the cam is beginning to work. Don
Which is all well and good in a race car, but in a street car you get about 1500 rpm worth of "slop" in the drivetrain when the engine is neither pushing the car forward nor slowing it down on compression. A "loose" converter is a monumental pain in the butt to drive 99% of the time. For me that's a tall price to pay for the few times a high-stall converter is actually doing what it's designed to do.
Back to the original question, does the car have a lockup converter? It may have failed. Sometimes a failed lockup will not want to disengage as it should causing the car to want to creep as you have described. I must add that I'm in strange territory here as I'm a bit old school and the electronic trannys are like metric stuff to me. I did the internet search on the problem and gleaned the info. You might try pulling the connector to the TCC and see if that cures it.
with a good quality built converter, you'll not have that slop. Under normal conditions you shouldn't even notice anything like slop. If your converter is freewheeling up to 2500 rpm (1500 rpm worth of slop in the drive line ) with light to moderate throttle you have some issues. Converters are tricky rascals to understand. I suppose if you had a grasp on fluid dynamics & could understand and explain bell curves, interest amortization, and logarithms with a deep understanding of dyno related torque curves of an engine you could easily make the jump and grasp the entire concept. Their designation is stated as stall speed related to RPM. But what's SO VERY important and never stated is the torque the engine is putting out at that given RPM. You could take converter A and put it behind a 250 hp (mild warm sbc) engine and it will put enough load on the engine to STALL the rpm climb at a particular RPM. Take the very same converter A and put it behind an engine that's making 400 HP and 450 ft lbs of torque at 2800 rpm (Something like a Buick 401 nail head) and that converter will have a completely different behavior and the actual RPM rating would be quite different. Now as far as the OP's creeping issue, I'd lay some money on it being the converter but it could be an internal fuck up of the TV cable.
I have a 2500 stall in my roadster. Now being a light car it has no real effect driving around town except that the shifts are smoother because of the slippage. I have put 22k miles on it this way. My 53 club coupe with a BB ford has the same converter but because it is a heavier car it is a bit more noticeable IE you can pull away from a stop and go through the gears and the RPM will barely fluctuate. The OP defiantly has a problem with the converter Most times in my 53 I have to keep my foot on the brake to keep from rolling backwards!!!!!
Im having similar issue's with my wifes 57. 327 w a healthy cam and a 700r. Also ours shudders pretty bad on deceleration unless I throw it in nuetral. Almost like its stuck in lock up. Would a stall help with these issues ? Sorry for the hi jack, but theres some good info being shared here. Posted using the Full Custom H.A.M.B. App!
that one probably just needs a vacuum switch, to switch off the converter when you let off the throttle.
Actually, I do understand most of that stuff - not that it's relevant - but my experience with a higher-stall converter in my Chevy 350-powered '55 Buick with a shift-kitted TH350 and a 3.1 rear gear was pretty much as I discribed. Perhaps the converter I had was bad, but excellent driveability returned when I replaced the aftermarket converter with a stock GM Chevelle unit. Soured me on high-stall converters for the street. Opinions will vary and pontifications will muddy the water on this topic once again, but in my case even the nationally-respected experts got it wrong. I gave 'em all the specs and the resulting converter's behavior on the street sucked. Oh well...it drives just fine now so I'm a happy guy.
FYI, a stock 70 Chevelle converter is around 1800 stall in the stock car. Your Buick weighs a bit more than a Chevelle but is likely running a little less HP/TQ (unless your 350 is built nicely) so your stall is likely in that 1800 range as well...
Thanks for the info. The engine is slightly warmed over with a mild cam but otherwise stock except for a Holley carburetor and performance HEI ignition and runs quite strong. With the higher-stall converter it acted around town (where I do most of my driving) much like Fuzzy Knight discribed in his post. It took too much rpm to get the car rolling and required 500 rpm more to keep it at speed than with the stock converter. The rpm didn't change much between gear changes as Fuzzy said and there was always an anoying delay between the throttle input and the car actually responding to it. All of this is at moderte around-town speeds. Also, when getting out of the throttle when coming up to a light or just to reduce speed the car free-wheeled with no engine braking at all. I found this to be very annoying. I do drag race the car and agree that it would launch stronger if the engine was free to wind up more against the converter. But then I'd run out of traction. Like they say, it's always something! Thanks for your input.
It is relevant & if you have excellent drivability with a stock converter ,,, well obviously you had no business with higher stall. Pretty easy to see what happened in your situation.
That's exactly my point. The OP should not expect a higher stall converter to "fix" his problem without being aware that there may be unintended consequences such as those I experienced.
Everyone is different but ,,, If I were running the 350 hp x & 400 ftlb at 3500 rpm Ram jet, I'd choose the 3000 rpm stall and drive it like a hot rod. If it crept at stop lights I'd ask my trans guy to check it out. If there are no issues I'd tell my converter guys they fucked up. Not that it's any fun but they would get the converter back to fix.
I'd expect it to be a converter issue as well. What I'd like to know is what kind of TV cable mis-adjustment would cause "creeping? The throttle valve controls pressure which determines shift points, and has nothing to do with the converter.
Mine creeps a little as well, but it's nothing regular pedal pressure wont control. I've got stock rebuilt drums. Posted using the Full Custom H.A.M.B. App!
Cable adjustment hasn't effected the creep, but advance the timing a little will make it pull harder. Posted using the Full Custom H.A.M.B. App!
If the TV cable is out of adjustment the tranny is not sure what to do. If it is to snug the tranny thinks there is more throttle input than there is creating more pressure try to get things up to what it thinks you are doing. If to loose it will up shift sooner thinking your just putting
Stopping a car with a standard transmission, WITHOUT depressing the clutch ...... the car will shudder, shake, jump and stall out. Same thing happens with a lock up converter that will not disengage, upon stopping. Scares the crap out of people when it happens.
We've never seen a problem running a 3000 stall convertor on the street, it acts just like a stocker pretty much. Both my Sons are running 3000 stalls and I ran one in my 23 too. All the cars would sit at a light with no pulling, would slow down the way a car should, and would pull hard when you got on them. But these are B & M Holeshot convertors, so maybe other brands are not of the same quality and perform differently. Don
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