torque converter question

this is not an A body Q, as it pertains to a D150 w/a slant in it. and 3.21s in the back.
and a 727. (yes I know how to tell the difference) the 727 stays.
IDK yet, if mine is a L/U version or not, seen them both ways in the mid 80s. if mine winds up as being a L/U, then this thread will be moot/ as the converter I have in mind, is for a non L/U version. If my truck is supposed to be a L/U version, the L/U function ain't working.

I will know as soon as I get the engine out, existing converter out, and see the input shaft.

the whole reason I ask, (and I don't yet have the old engine out, so I can see what I think is behind that shield) is that I believe my ring gear may have issues/ as sometimes I have weird noise while cranking, that sounds like bad teeth on ring gear. I have swapped starters so far, to try and eliminate that possibility. it still does the same, with the other starter I put in place. if it weren't for that possible problem I would not be worrying about doing anything with the existing converter. except to "run it". I think whether it is noisey or not on any given start, is where the converter stops when last shut off, and the starter has to take off from along the gear, on the next startup.

truck seems to drive OK, but is a dog off the line. (engine currently being built, will help solve that problem) 1st Q, anyone know what stall would have most likely come stock in the truck? FYI it's an '85.
I have come across a B&M "Tork Master" for what seems a fair price, not much more than what a stock "rebuilder's" converter would cost (I think anyway, I haven't bought a converter for a 727 in a few years) Certainly not $4-600, like most aftermarket 727 converters I see, tend to go for. They are advertising it as being 1900-2100 stall, and "not for big block/supercharged application". B&M's catalog number is 10416, that I am considering.
How would this converter be, for that application? I don't want a 12" like many 727 converters were. What would determine whether this would stall at 1900, or whether it would stall at 2100? I know there are a few determining factors here but do not remember what they would be.
If my fears do come true, and I have to replace the converter while the engine's out, I want to go with an 11" or maybe a 10" if there is such a thing, for a 727. but that is one thing that I have not been able to find, is the converter diam. for this unit. Anyone know?
as far as the standard transmission shop "rebuilder's special" converters go, I remember from past experience, that for most body/engine/trans combos there was a "low stall" and a "Hi-stall" version. How low is "low stall", and how high would "hi-stall" be, if I go that route?
Any quality issues to be aware of with B&M?

Engine torque determines the stall speed of a given converter. Example:
My Valiant with a 9 1/2 inch converter will stall at about 3200 with the 170 engine, and about 3800-3900 with the 225 engine (same converter).
You can determine whether the trans is a LU or not, by getting the numbers off the edge of the trans pan rail. My Mopar.com has a trans decoder chart.
As for the B&M converter it will probably stall less then 1900, as most stated stall speeds for converters are rated for V-8 engines, and the slant six will have less input torque, so therefore a lower stall speed.

It's a half ton truck with prairie gears and a slant 6. A converter isn't going to make a world of difference. A gear change, a supercharger kit or another engine would be more effective.

roccodart440 said:

It's a half ton truck with prairie gears and a slant 6. A converter isn't going to make a world of difference. A gear change, a supercharger kit or another engine would be more effective.

Click to expand...

Well it's getting another engine. Though this other engine is also a slant 6. But a slightly improved version.
Like I'd said I wouldn't even be thinking about doing anything with the existing one if I didn't think that the ring gear had an issue.if I thought that I could replace the ring gear without replacing the converter I would. But if there were any improvement to be had while going down that road, I figured now would be the time to kill that bird with the same stone, so to speak.

How would this one that I am looking at, compare to the original stock one? (Assuming again that what is in there now is a non lockup version) I'll have to either wait till I have it apart to see, or get that PK number from it and see what I can decipher from that.
If I find out that it is a lockup then I'll be looking into a "rebuilder's special". It drives like the one in it now, is a non lockup.
And I have never heard the term "prairie gears"
What is meant by that?
Can anyone answer me on whether the converter I am considering is a 11 or a 12" unit?

To undogify your combo, your slanty needs;
a true 2800TC and
an Effective starter gear of at least 9.5/1 corrected to a 24" tire. and
at the very least ,145 psi cranking cylinder pressure at whatever elevation you are at.
Do not consider the Wide-ratio 2.74-1.54-1.00 trans. Yes it will blast -off better but will lay over worse when it hits second.

With 225/75-15 tires for instance (28.3tall), you will need a starter gear of 9.5/(28.3/24 x2.45) =3.29s, rounds to 3.21. Your engine will still lay over when it hits Second Gear. The cure for that is more; or less..
More shorter tires, or more rear gear, or more cylinder pressure.
Or Less weight.
Yes the damaged ring gear on the current TC can be replaced. I knew a guy once who could weld pretty good too..... but if the engine is already out, just replace it.

A big cam or low cylinder pressure will want a bigger number second gear, especially with tall tires.

Some of what I am about to add has nothing to do with what I asked in this thread but since it was brought up here goes.

I have new 235/75-15s coming for it. Not much different in height than 225s. I originally wanted 275/60s in back and something like 235/70s in front but it has 235s on it now, and I ran across a set of 235s for a too good to pass up price. The ones on it now are from like 2005.
Plans are for a fresh 20-over short block, (Hey that's what the machine shop came back with) possible slightly shaved deck. Oregon 819 regrind of stock solid cam. Ported peanut head with oversized valves and definitely a shave of the head. Opened the exhaust manifold outlet to a true 2-1/4" with a die grinder. Super 6 with a brand new genuine NOS BBD at least for now, may eventually go to a small 4 barrei if I find the one I want for it (400 cfm Carter AFB) 3.21 gears and 727 will stay.
Given that, what do you guys think of the converter I am considering?

Prairie gears are tall gears. 3.23 through 2.xx gears.

Trucks usually have 3.73 - 4.11

I don't necessarily agree a converter will not help. Modern converters are marvels of engineering and they can make a huge difference if you communicate honestly with your converter manufacturer. Also, you can quickly identify a lockup transmission if it has a hole in the input shaft of the transmission. Hole in the input shaft = lockup, solid input shaft = non lockup. Getting more grunt from a slant six I like to look at as a challenge. I don't like to call it difficult. I pretty much echo all of the advice so far. More cylinder pressure, bigger exhaust, (you'll want to see what I did here Exhaust Manifold Mod) very careful camshaft choice. I say careful , because with a heavier vehicle like a truck, over camming a slant is even easier to do. They are easy to over cam in the first place, so watch it. You also want a good hot ignition curve. Unless you really raise compression a lot, you can probably get by with having it all in by 2500 RPM. If you end up with say 160 PSI or more, you'll want to limit that to all in by 3000 or 3500 to ward off any possible spark knock. I would say maybe 12-15 initial and 32-34 total in by "somewhere" around 2500-3500 all dependent on what it likes. Contact Ken Heard at Oregon Cams and he can suggest a good grind for you. Send him your core and 89 bucks later you have a cam.

Yup already talked to Ken, and a couple of/6 truck guys at the/6 forum, for what has worked for them and what hasn't.
The exhaust manifold that is going onto that engine I've already opened up to match the flange gasket. I was surprised at how off center the outlet was before I did so. I talked to you about the manifold mod around the same time you originally put it up here, we must have been reading minds as I was working on doing just that to 2 of them, at the same time, as you put it out here on the forum//the 1st of which went onto my son's slant 6 truck when I super 6'd that one, and the one that will wind up on my own slanted truck engine.
As far as knowing if mine is a lockup or not, I have never had the engine or trans out yet. I know about the end of the input shaft differences but thanks. I just haven't crossed that bridge on my truck yet, is all. Never know what someone else knows until you say something. As far as most trucks having 3.73-4.10, all of my 70s and 80s 1/2 tons have been in your "prairie gears" category my 3/4 and my dually were 3.55-4.10. my 90s trucks (mostly Dakotas with 1 ram 1500 in the mix) were all 3.55 except for my 1, 4wd dakota/ that one is 3.91.
I'm not planning on an OD swap anytime soon so the 3.21 stays in my d150. I'd like to find a 3.21 gear set for the 8-1/4 in my B body Sport Fury.

Thanks for all the info but seems like everyone is skirting my original questions from my OP.
Still looking for some answers to what I put in up there.
More so on a 904-998-999 than 727s that I have had, but among stock and "rebuilder's special" converters, I knew when a car had a factory hi stall because in 1st gear "parking lot speed" the hi stall versions were always "whinier" than the factory low stall versions. How much difference was there in stall speed between low and hi stall from the factory?
I haven't had a Mopar performance catalog in some years now but the last couple I had listed converters according to a k factor.
Stall speed has always been about as much of a black art to me as trying to decipher camshaft specs and what a change here or there would do for me, as it was even before they came up with that idea. The k factor seemed to confuse things even more.

And Rusty I thought I'd sent you a pm a couple weeks ago, you had posted to someone looking for a stock slant cam that you had a spare or more that you could help them out with. I'd asked if you had more than one, and how much you'd wanted for one. I'm stuck between 2 ideas for my engine build. I plan to send my stocker off to Ken at oregon cams to be ground into that #819 for my "plan A build" and was thinking of sending in a 2nd one to be turned in to a cam more suitable for my plan b idea (which is a home brew junkyard turbo slant) maybe it didn't come thru?
But now that I think about it, Ken wants something like $130-some for the 819 on a brand new blank.... Maybe better to keep my original for plan b, and just order a brand new 819 vs paying you for your spare plus paying shipping 2x, once from you to me then from here to Oregon?

well, I guess the specifics of that particular converter I was looking at, go out the window. wont work. I just found out by PK number that mine IS a lockup version. but most of the rest is interesting, for different reasons.....

So what exactly do different stalls eg a 3500 do differently compared to a 1800 stall?.
You often see a Hi stall in a high Hp car and often wondered how they work differently.
Cheers

FLoor it and it goes to 3500 before taking off. AKA flash stall.

Drive normally, it acts pretty normal.

roccodart440 said:

FLoor it and it goes to 3500 before taking off. AKA flash stall.

Drive normally, it acts pretty normal.

Click to expand...

Hi Roccodart
Ok mate thanks for that!, that explains it pretty simply.
Thanks