johnnyjaws

what is a stock stall speed on a 1970 th350 trans

GEARMAN69

Generally the stock stall in most TH350 applications with good back brakes holding it is about 1800 rpm.

BlackGold

Of course, it also depends on engine torque. That same converter behind a stout 455 will stall higher.

johnnyjaws

well guys I bought a big block .going to hook it up to a rebuild th350 with b&m shift kit a lot of people say go 2000 stall should I go a little larger rear has 252,s but not for long going to a 343 rear and is be running c heads 1970 engine rebuilt at 33000 miles on a 1973, 88 block has a rpm performer intake on it and am putting a compcams 274 in it and a 870 4150 carb on it has a 600 or 650 on it now. I was thinking a 2200 stall.? I want an all around car wont be raceing it light to light couple smoke outs and highway driving what do u think

don71

I would put your number one priority on changing the rear ratio. Let the higher stall converter swap to be later on.

Changing the rear ratio, will feel like a lot of "new" horsepower now, that you all ready have.

Changing the stall, will feel like power too, but you'll burn through twice as much gas=mileage.

Your choice depending on your goals.

Another good discussion about this is, just how "tight" or "loose" is this converter going to be in any given application.

Grumbler

New gears first for sure. I have a 2500 stall with a 455 and 3:42's, perfect for the street IMO. I have the 200-4R, 1950 RPM at 60, your TH350 would be higher but still cruise nicely

gs72

Read this before you decide on a stall speed.
http://www.racewithjw.com/Torque_Con...tion_Guide.pdf

gs72

Here is a little better explanation of the K factor:

" Claiming a converter has a specific stall point without making reference to the motor it’s behind is misleading, as there are too many variables. The factory converter, which may stall at 1500rpm behind a stock motor, may well stall at 3000rpm or more behind a blown big block. Technically stall speed is not just a function of the converter. It is also a function of engine torque.

This can perhaps be easily described by defining the ‘K’ factor. ‘K’ is simply the constant in the equation K = rpm/sqrt {torque}. The equation describes the observed behaviour of the converter behind a specific engine. What this allows us to do is determine what the stall speed of a given converter will be if put behind a different engine.

For example, if a motor has 400lb/ft (542Nm) of torque and stalls a particular converter at 3000rpm, K = 3000/sqrt {torque} = 150. Since we know K = 150, we can predict the new stall speed if the torque is say 500lb/ft (677Nm) by changing the equation to rpm = K*sqrt {torque}. In this instance the new stall would be rpm = 150*sqrt {500} = 3350"

You can download a square root excel spreadsheet to figure out the square root calculation. You can use a desktop Dyno app. To figure out your engines torque numbers. I think summit or comp cams has a free one on their sites.