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Higher stall - yes or no?
https://slantsix.org/forum/viewtopic.php?t=24334		 Page 1 of 2
Author:  63Dart170 [ Sat Aug 04, 2007 7:06 pm ]
Post subject:  Higher stall - yes or no?
My 63 Dart 170, with the pushbutton auto is finally not leaking oil courtesy of another new rear main seal, and now it seems that there was a tranny fluid leak from out of the bellhousing. They're obviously going to have to drop the tranny to fix the leaks.

My question is this - if the torque converter is leaking and needs replacing for any reason, would it be a good idea to get a higher stall tc for my street driving needs since the tranny will be out of the car?

I have the 170 engine, CompCams 252 camshaft, 2-BBL, 2 1/4" exhaust, head shaved is shaved .020" and ported and polished. With all of this, I'm inclined to think a slightly higher stall speed might be ok because it really seems to come alive a bit higher in the rev range than stock, but I don't want to put too much stress on the rearend or make it too jerky for just regular driving with harder launches. I will never race this car, I just like to keep my right foot happy once in a while.
Author:  SlantSixDan [ Sat Aug 04, 2007 8:05 pm ]
Post subject: 
Torque converters don't leak. Transmission front seals and bushings can leak, but not torque converters. Putting a higher-stall converter behind your engine as described will tend to reduce your fuel economy and low-RPM acceleration.
Author:  argentina-slantsixer [ Sat Aug 04, 2007 9:00 pm ]
Post subject: 
not to mention the need of increasing the cooling capacity of the lower rad tank (in regards of trans oil heat interchanger) and probably upgrade with a B&M or other trans radiator.... How much "higher" seems to come? that might be an improperly set timing curve... I bet you're below 10°BTDC of initial timing
Author:  63Dart170 [ Sun Aug 05, 2007 6:52 pm ]
Post subject: 
Thanks for the replies - I don't need this to turn into another expensive project with the extra cooling capacity (let alone the cost of a new torque converter), and I don't want to lose any fuel economy or low RPM acceleration.

And Dan, I'm not sure if my transmission guy actually said the torque converter would be leaking, but he did say he could pressure-test it, and he did mention the bushings and the pump seal.

My initial timing is set at 2.5 degrees BTDC as per the owner's manual, but I can probably get away with changing that a bit with the changes made to the engine.

Since I don't have a tach, I'd guestimate that probably around 1/4 to 1/3 throttle it's noticibly more powerful, but probably like stock or so from idle to there. Using my butt dyno, it's about the same or even a bit better from a dead stop than stock (can maybe chirp the tire if I turn the wheel all the way to one side), and it can usually chirp the tire when it shifts into 2nd gear under hard acceleration - and I know this might be a dumb way to measure power, but the tires it has aren't the greatest anyway. At 50 or above, if I step it down, it accelerates much better than stock.
Author:  slantzilla [ Sun Aug 05, 2007 6:58 pm ]
Post subject: 
A converter can leak. 904 is notorious for cracking the ears that drive the pump. Replacement is the only option.

Higher stall speed helps low speed acceleration, not hurts it. You can easily increase stall speed 500 rpm or so with no need for an extra cooler.
Author:  63Dart170 [ Sun Aug 05, 2007 7:05 pm ]
Post subject: 
If I increase the stall speed by 500 RPM, how would that affect low-speed drivability? Would each start be more jerky, or is that really a small change in the grand scheme of things?

I wasn't really planning on a new TC to begin with, but if it's going to be taken apart, I thought this would be the time to do it if it's worth it.
Author:  SlantSixDan [ Sun Aug 05, 2007 8:15 pm ]
Post subject: 
Quote:
A converter can leak. 904 is notorious for cracking the ears that drive the pump. Replacement is the only option.
Haven't seen much of this failure behind 170s! :twisted: I suppose it's possible.
Quote:
Higher stall speed helps low speed acceleration, not hurts it.
That is entirely dependent on the characteristics of the engine.
Author:  slantzilla [ Sun Aug 05, 2007 10:28 pm ]
Post subject: 
Quote:
If I increase the stall speed by 500 RPM, how would that affect low-speed drivability? Would each start be more jerky, or is that really a small change in the grand scheme of things?

I wasn't really planning on a new TC to begin with, but if it's going to be taken apart, I thought this would be the time to do it if it's worth it.
You won't even notice it until you stand on it. :shock:
Author:  1974duster kev [ Sun Aug 05, 2007 10:54 pm ]
Post subject: 
I haven't gotten or installed a 3000rpm converter i'm getting but from driving my dads dart 360 theres no real noticable difference from stock and his is if i recall a 2500 possibly 2800. if that helps any there ya go.

Kevin
Author:  Charrlie_S [ Mon Aug 06, 2007 4:52 am ]
Post subject: 
Quote:
Quote:
A converter can leak. 904 is notorious for cracking the ears that drive the pump. Replacement is the only option.
Haven't seen much of this failure behind 170s! :twisted: I suppose it's possible.
I used to have that problem, on a regular basis on my 170. I cured it by puting a radius in the corners of the slot. From what I understand, most newer good quality converters, use a better meterial for the pump drive, and already have the radius in the corners. It was many years ago that I had the problem.
Author:  slantzilla [ Mon Aug 06, 2007 7:00 am ]
Post subject: 
http://board.moparts.org/ubbthreads/sho ... ost3684250
Author:  63Dart170 [ Mon Aug 06, 2007 12:59 pm ]
Post subject: 
So basically, if I would get a TC with a slightly higher stall speed, I wouldn't really notice a difference unless my foot is heavy. Would this be putting too much strain on the rearend? I'm quite sure I'm still under what a stock 225 would be putting there anyway, so that's probably nothing I have to worry about.

Well thanks for all the advice - I now just have to decide if I think it's worthwhile to get a new one - if the stock one is ok, I'm not going to change it, but it might be more fun around town in the summers - when school's back in session, I drive mostly highway miles and a higher stall TC won't do me any good anyway.
Author:  slantvaliant [ Tue Aug 07, 2007 6:35 am ]
Post subject: 
Quote:
Torque converters don't leak.
Anything that is supposed to hold a fluid can leak. Converters can leak from the neck, as mentioned, but they can also develop cracks in the body, at any welds, stress points, etc. It's rare, but it happens.
Author:  Dart270 [ Tue Aug 07, 2007 11:01 am ]
Post subject: 
I would definitely get a higher stall converter, by about 5-700 rpm as you suggest. This will make your low speed takeoff faster, but will not be noticeable unless you stand on it, as Slantzilla mentions.

I noticed only a 1mpg drop when running 2800 rpm and 3000 rpm converters compared to stock, so that will be negligible with a 2300-2500 converter that you are aiming for. Midwest Converter makes excellent units and knows how to build them strong and to suit the Slant 6. They use the strong alloy pump drive hub.

Lou
Author:  Rick Covalt [ Tue Aug 07, 2007 12:39 pm ]
Post subject:  Your all wrong.
Come on guys, Dan said they don't leak so you must all be wrong. I expect you all to edit your posts. :lol: :lol:
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