I'm starting to wonder why we decide to go with these High stall converters. I dont drag race at the track. I do some spirited driving on the street and I DO intend to run the car on a few road race courses just for fun.
Here is the combo: 440 based 493. 10.8 squeeze, MP '509 cam, 2" TTI headers, Edelbrock heads, 850 carb. 727 with 9 3/4" converter, Gear Vendors overdrive. 3.91 gears. The car will move off of idle, but it slips more than I like. If I lean on the throttle, the rpms go up but the car doesn't respond in direct proportion. In short, it slips too much before the stall rating. It feels like I'm leaving from a standing start in a manual trans car. The engine idles nice at 900 rpms.
My 2007 Ram truck pulls nicely right from idle. The fairly stock 360/904 in my bro-in-laws 72 Duster also responds quickly right off of idle. I know... stock cams are designed for that. I just wonder if a stock converter might work for me. I am not as experienced as others in terms of torque converter science. My engine makes great torque and HP even at low rpms, so do I really need such a high stall unit?
Freeway driving feels lazy too. If I'm rolling along at 65 mph and try to floor it, there is a noticeable lag before the car really responds. At 65, the car is going too fast to downshift to 2nd automatically, and for some reason, the GV will not unlock from OD until it slows below 45 mph. Yeah, I know... 65-70 is the speed limit and I shouldn't exceed it....Still, with the car rolling along in OD with a final drive of about 3.05, it feels sloppy. It feels loose from the standing start and sloppy at cruise speeds. I talked to the builder of the converter. He said that he could cut it open and change a few parts to lower the stall, but the question is... how much? 200 rpms isn't going to do it. I'd like the stall to be somewhere around 2000.
Would it make more sense to look for a 11" converter? As is, the car will boil the tires if I just stab it from the start. I can fry the tires halfway through 2nd gear. I have no complaint about the performance at full throttle. My issue is part throttle starts and any other situation where the car is running "under the stall" rating.
Thanks, Greg

Who made your converter? A good quality one will minimize the issues you're experiencing. Also, the overdrive will place your engine and converter lower in the rpm range, where your high stall converter is naturally going to be less efficient.

The 509 is known to be a lazy, old school cam. Not helping your combo either.

Yep.. The 509 is a very lazy camshaft.

I should have mentioned that before I installed this converter, I had a 11" TCI converter in the car. The car felt great but a Dyno operator suggested a looser converter for better dragstrip performance. I went with a local company in Sacramento, D and P converters.
I had a Comp Cams XE 285 flat tappet in the car with this converter. The car felt about the same.
My question though is maybe a little hard to answer: With an engine nearly 500 cubic inches with over 500 ft/lbs or torque, how low of a stall can I go and not end up with an engine that bogs out of the hole?
Maybe I should have stayed with that 11" TCI converter. Oh... I'm not married to the '509 cam. I may switch back to a Comp since they now offer a better hardening process.

I've got a PTC converter behind my 440 (.474" cam) with a stall rating of about 2800 rpm. Feels a little mushy for my tastes too under the driving conditions you describe. I'm going back to a stock 12" soon. It should stall at around 2200 (according to Pat Blais).

I'm no expert, but experienced something similar: The car felt like a manual transmission with the clutch pushed in part way until the stall speed was reached. Anything below that and my throttle felt "spongy". In cases where I spent some time below the stall and then mashed the throttle, the engine would rev and then it would feel like I "Popped the clutch" when the torque converter decided to catch.

I went to several tranny shops who suggested swapping to a lower stall converter.

A random person at a car show explained to me that the converter was "draining" faster than the pump was filling it when below stall. The "Laziness" was a result of the torque converter filling first and then doing what its intended to do. I took my car to a knowledgeable shop and mentioned this. They installed some sort of "Block-off plate" in the valve body. (This is what I was told).

Now the car acts like it was supposed to: No more hesitation, No more spongy throttle.

My

Very interesting post. I have only put about 300 miles on my car since finishing it and I am wondering if a stock converter would'nt be more fun to drive. I have a 540 ci hemi with 10.8 compression, 248/254 @ .050 roller cam, 3.54 Dana and 3500 stall converter. I used the converter after much discussion with one of the top trans builders for the 727. Part throttle is just "mushy". Full throttle is not even possible on street tires so what is the point of all of that stall? I will wait until I get a chance to run it at the track on slicks to decide to go to all the trouble to change it. No doubt the et will be better with the converter I have, but I drive much more on the street.

Thanks Joey, I do too! LOL

Lynn

if you want a snappy response driving around town, an 11' would work well for you if you don't have to idle too high because of your cam. also keep in mind with an 11' running a 1/4 mile you will be hard pressed to get the car into its power band. that's the problem i have with my 440-6 RR. i tried a 3500 converter and on the street it was a big slop box. i went to an 11' and while it is snappy on the line it seems in the 1/4 mile i'm leaving alot behind as the race is over before before i'm actually making full power. also due to my cam, i have a world of trouble getting a decent idle sitting at a light because the converter is locked on. i just got a PTC 2800 that was built for my car factoring in engine size, 6-pac, gear ratio and ridiculously wide Mickey Thompson tires. it will be a bit before i get everything back together again but should be in the next month or so. i'll let you know

The best verts to me are fairly tight feeling stall (I call that "responsive" to throttle input) but can flash right into the meatiest point of the torque curve in high gear. I have always hated a part throttle 'slipping clutch' feel in a daily driver, won't ever have one that way. That's why I drove sticks all the time before converter science technology caught up.

what's the part of all that juicy stroker "dyno" torque if you can't feel it until 4500-5000 RPM? That's why I don't chase top end HP with the cam, build the short block for torque and let the head flow put the HP where you want it. On the street you really want more of a road-race wide powerband, not a Drag Motor type torque curve....unless it's a really light car that can't hook what you have. The smaller diameter verts are more efficient and obviously less rotating inertia at high RPM. you've got to find the right balance for your combo but for strokers you're almost always better with a custom built unit.

What stall is this converter rated at?
From what you've written, it appears that for street use, far too much stall speed.
Properly applied, a higher stall converter is great, improperly applied, the worst performance investment you can do.
Graham

We just took the 72 Runner for one stop on the power tour. Its powered by Bobby's (Wize's) old 508 stroker, six pack intake, HP manifolds, 9 1/2" UCC converter......currently there are 2.94 suregrip center in the 8 3/4 and a 255/50R16 tire.

Off the line the car honks and screams. The converter in this car does not slip at highway speeds (atleast to the point that I notice it) I will be checking slippage later today when I get out of work to calculate a true % of slip.

This converter currently feels to me that its tight when Im cruising or loafing around. Apply light to moderate throttle at any speed in any gear and it accelerates, (I dont feel rpm slippage and then the car going) and when I mash it it will flash and go.

Kinda like the way Bobby described how he wants the converter to work.

The cam in the car is from Scott Brown and I had him spec out the UCC converter as well. If you call him tell him I said Hey!

Why did you not install the cam as it was before ? First thing I would do is put it back advanced, it will cost you a gasket or 3 and time .

as stated, you have to decide what your looking for when selecting a converter. i heard alot of good things about this PTC unit i bought, and although they were clearly more Chebbie directed i was impressed with the guy that took my order. he asked the right questions, followed up with a call when he needed more info and the fact it took 2 weeks from time of order to when i got leads me to believe it was custom built for my car and driving. hopefully that isn't just 'smoke and mirrors'!

I've got a similar set-up in a B-body...

484;shift-kitted Torqueflite;street-hemi converter;3:91's...

Am experiencing nothing like what you're describing...

What did you have, trans-wise, in front of the 4:10's???

Watch out with dropping your converter too low. Too low of stall is going to give you one hell of an rpm drop from neutral to drive if you have too big of a cam.

Quote:

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I've got a similar set-up in a B-body...

484;shift-kitted Torqueflite;street-hemi converter;3:91's...

Am experiencing nothing like what you're describing...

What did you have, trans-wise, in front of the 4:10's???

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Your "street-hemi" converter is likely nowhere near as much stall as his.

He says 3-grand...

Mine's 2800...

Moot point...