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| How dose one figure optimal converter stall speed? https://slantsix.org/forum/viewtopic.php?t=33850 |
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| Author: | wjajr [ Wed Feb 18, 2009 6:27 pm ] |
| Post subject: | How dose one figure optimal converter stall speed? |
Today I talked with a transmission shop regarding restoring the factory function to my R/M valve body equipped 904. I told him that possibly I need to increase the stall speed, as the present converter seems to be locking at around 1700 rpm. Rather, that is when the rear wheels start to spin when standing on the brakes in the garage, so I guessing that is close to locking rpm. At 1200 rpm she wants to go, but will sit still with the brakes applied. This guy said that; "I don't want a higher stall converter" for street use. I explained that the car has a rather aggressive cam with a 3.55 rear, and won't idle real well below 800 rpm in gear, or 1000 rpm out of gear. I tried to explain that she doesn't make a lot of torque until 2000+ rpm, and it is gutless under that rpm. He said he has a pile of high stall units he has pulled because customers didn't like them for street use. He than said unless you 300 to 400 hp, a stock stall is fine... I'm still scratching my head. Someone recently said that their car was acting the same as mine, and a higher than stock stall converter reduced the chomping at the bit while stopped at a light. I also suspect that a higher stall would liven up take-offs a bit also. So how dose one figure the best stall speed for street use? |
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| Author: | Doctor Dodge [ Thu Feb 19, 2009 12:32 am ] |
| Post subject: | |
At what RPM does the car "cruse" at? Where does it start to have power in the RPMs? Set your stall speed just below that RPM point. For me, 2800 is about right for the street. (3000 RPM is my street RPM "sweet spot") DD |
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| Author: | wjajr [ Thu Feb 19, 2009 3:58 am ] |
| Post subject: | |
Thanks Doc. I guess the transmission mission will have to wait a few months until winter leaves the area to figure out how the car now runs. I rebuilt the carburetor in late December just before the snow hit with only a short test drive before putting her up. Now I'm about to install over sized valves, and a mild port & clean-up if not presently equipped. From my notes, with a 3.55 rear 60 mph = around 3000 rpm, and I would have to say she starts to pull around 2800 rpm. Would enlarging of the valves change the torque curve much? I have a 68' block & 76'-77' 904. What spline count would the torque converter need? |
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| Author: | Dart270 [ Thu Feb 19, 2009 6:27 am ] |
| Post subject: | |
Your guy is out of date. A 2800 stall converter will REALLY wake your car up. The newer converters (1990-up) are quite efficient, so that it will feel almost like a stock converter until you romp on it, then it will stall up. Call Midwest Converters or PTC or Continental or there are a few other good ones out there. DO NOT buy a GER converter (may have changed names). Lou |
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| Author: | Doc [ Thu Feb 19, 2009 9:55 am ] |
| Post subject: | |
Quote: ... I have a 68' block & 76'-77' 904. What spline count would the torque converter need?
That trans should have the 7/8 diameter input shaft with 27 splines. (a "big hub" converter)If you get a converter custom built, stress that you want it efficient. Smooth fluid flow inside the unit makes less heat and that means more power to the wheels. DD |
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