727 converter question

This is in a D150 with a /6 and 727. Lockup version.
I'm replacing the engine, with a fresher one, just rebuilt, reground cam, block and crank milled 0.100" between them, oversized valves, ported head etc.
I'm having to stab another converter in there while engine is out/ only because of a bad ring gear courtesy of the prior owner. Trans works fine, fluid as red as it would be if off the shelf etc. I drove it enough to evaluate the trans on the original engine. (Still runs alright, just want more power/ I'm staying with a /6 for a replacement at least for now.

When it comes to 727 converters why does nobody offer a performance converter for the lockup version? No matter what engine might be in front of it?
Also, they show a low stall and a hi stall from the factory. How high is high, how low is low on the factory converters.
I got a deal on a Dacco 558 that is supposed to be a reman to factory hi stall specs. I settled for that since B&M, TCI, etc show nothing for a 727 Lock up. I was wanting maybe a Tork master or the next one up, nothing crazy

I know we have to talk non Lock up for a minute but how does the Tork master compare to a factory hi stall? All else being equal except let's say for a minute I found a non Lock up 727 to fit my engine. Is a hi stall for non lockup (factory converter) the same stall as a factory hi stall for a lockup trans?

I can't directly help, but the FSM usually lists the stall speeds. I don't have a 77 truck FSM so I can't help.

Huh my last reply I added isn't showing up now.
Doesn't have to be a 77 particularly, my truck is actually an 85. But I wouldn't have thought that they would have changed what I asked about much thru the years other than maybe pre lockup and post lockup?

Who knows what Chrysler did in that era of smog. Not sure why I thought you had a 77.

I have an 87 Pass car manual somewhere in a box, not that it would help, no /6 in pass cars of that era and I am pretty sure the slant was gone in trucks then.

As I understand it, and I'm not a transmission guy. The concept of a higher stall on a lock up converter pretty much defeat the purpose of the lock up converter.

A higher stall allows the converter to slip until it reaches the stall speed, that allows the motor to get up into the power band more quickly. A lock up converter locks up any slip in the converter at a specific rpm, typically at a pretty low rpm, the purpose was to increase gas mileage. Typically, the lock up converters made the vehicle feel like you had a standard transmission that you shifted into high gear at 30 mph, would still go, but not very fast. A slipping converter builds more heat, and poorer gas mileage, but gets the motor into the power range faster (sort of like staying in 3rd gear at 30 instead of shifting into 4th).

Depending on the rear gear ratio, and the the highway rpm the motor is turning at a specific mph, you want the converter to lock up below the cruising rpm. With a 2:76 rear gear at 65 mph, that rpm cruising range is pretty low. A typical early lock up would lock the converter in around 25 mph, not too bad in town, but a killer as you were leaving town or wanted more power.

Back in the early days of the lock up converter, you could slightly adjust the rpm range the converter would lock up. Often they would lock up a little too soon most the time (some as soon as the transmission shifted into drive), really killing the power level of the already weakened motors. By adjusting the lock up rpm range up 200 to 300 more rpm really made a difference on how the car/truck ran. Unfortunately, I don't remember that process, the mid 80s was a long time ago.

What should be the stall rpm, and what should be the lockup rpm? See the problem with a high stall lock up converter? Gene

hopefully this is what op is looking for. 1st pic is from 1986 fsm and 2nd pic is from 1984 fam. both trucks. i have an 1985 but it is in garage. not going out in the rain to get pic. both 904 and 727 used 10 3/4 conv per fsm.

Lockup or not has no affect on stall speed; in the FSM's after '78, when lockup was introduced, the stall speed charts make no distinction between lockup and non-lockup. '78 shown below.

According to wikipedia the slant 6 was used till 1987 , V6 88/89 ???

A lockup converter for a gas engine A518/46RH or RE should be the same. I've seen performance converters for them.

in trucks. 83 was the last year for a /6 in a car.
and that last pic of a factory service manual shows a 904 and a 904 HD (whats the difference between these?) Anyway this /6 has a lockup 727 behind it.

I’m pretty sure they will make a performance lockup converter for a 727, but it would cost more than the rest of the drivetrain. Think bolt together converter. I very briefly toyed with the idea. BRIEFLY!

I'll answer this ... no , I'm 99% sure the spline count is different so you can't put in the wrong convertor.

I drove one of those early lockup convertor cars and my god do it suck.

You should be able to switch your lockup trans over to a non lockup by changing the front pump, assembly and input shaft assembly along with the non lockup valvebody .. The transmission case is the same between the 2.

The 998 and 999 are HD versions of the 904.

998 had 4 disc front and rear clutches, 999 had 5 discs in the front clutch.

yeah i know you cant interchange converters between lockup and non in a given trans..... and I know I could scrounge parts and build this trans into a non lockup.
That's why I said "non" lockup for a minute". how much difference between the B&M converter I asked about and a factory hi stall non lockup converter for a 727?

for whatever it's worth, [and coming from me, probably nothing ! ] my 78 factory hi-stall 727 converter behind an E78 cop 360 stalled at 2700rpm.
this was a new engine/transmission assembly [carb-to-pan, not a re-man unit] direct from chrysler, i won [] at the street rod east coast nationals in timonium, maryland [baltimore] by entering the "mopar country" mini event held there that year. [a year or so later, the east coast street rod nationals was moved to york, pa. and has been there ever since]

Sorry I can't answer that .

i would say it's one of those "it depends" kind of answers.
B&M has many choices when it comes to converters, so if a guy wanted to compare one of theirs to a factory one, a specific B&M model would need to be mentioned, or what rpm converter a guy was thinking about obtaining.

Back when they were available new, B & M bought brand new 10-3/4” converters from Chrysler then some were just repackaged, some were cut and modified.

No way to know what you are getting unless you can find a BOM from B & M from back in the day.

I gonna bet anything from them today doesn’t use the original design impeller and internals unless they found a stash of the old converters.