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I'm thinking about stroking a 440 with a 4.15 crank instead of the 3.75
Do you know what kind of a cam would be a good kombination?
I'm thinking baout something more radical than stock but I don't want a converter with more stall than about 2000 rpm.
Do you know about enything else to consider with a 440 with this stroke.
(that would make about 496")

[dave-r]

A name - any name or nickname would have been nice. Where are your manners boy?

The extra long stroke will give you more power and torque over the whole rpm range of your engine due to the increased capacity. How much power depends on how well the heads flow. They will need to flow well because of the increased piston speed.

How much do you know about stall speed?

My 440 uses a 2800 stall convertor. When I put it in gear the revs are pulled down to 600 rpm and I have to hold it hard on the brake as it tries to drive away. Do you understand why? To cure it I will need a 10" 3000-3500 convertor to make it drive like a normal car.

Let me know if you want to learn more about it and I will give you more information.

But in a nutshell. The extra capacity and torque of your engine will make a 'hot' cam seem more docile and with your standard cam it might make your existing convertor feel like it has a higher stall.

[frank]

can i make another suggestion? just call up any of the cam companies tell them what you have,how you want the engine to perform,and your price range,they deal w/these kind of questions all the time and are very good at getting the right combo for you,then if your not convinced you can check it out w/computer software you can figure what kind of hp,torque,ect...before you get started

[Christer]

I am beginning to realize that I need to know more about stall speed and converters....
Please, explain to me.

[dave-r]

Big topic. No time. but I will do my best.

Stall speed ratings for convetors assume your engine is putting out 'this much' power. Say about as much as a warmed over small block chev as that is the bench mark most manufacturers use.

But the actual stall speed of the convertor depends on the torque output of the engine you have.

The more torque you have - the more stall speed you will have from the same convertor.

Think about it this way. If you were trying to stop an engine from turning (stall it) it will be easier if the engine does not have much torque. A small engine with a big, high rpm, cam will stop easily if you suddenly stuck a screwdriver in the flywheel or something. (don't try it!)
Where as a stroked big block will not only bend the screwdriver it will tear your arm off as well without even slowing down.

So. An example would be a 340 with a 727 trans.
If you use a standard convertor from a 440 the 340 would stall at a very low speed. This is because that convertor is built for a big torque - big block.

If you took a 440 and fitted a small block convertor it will stall higher than stock because the convertor was designed for a smaller torque output. (cheap way of doing it)

So if you fit a cam that robs you of torque from the low rpms you will need a higher stall convertor just to get you back to normal.

So with my big cammed 440 I use a 10" unit and it stalls only slightly higher than stock.

[Tore]

Torque converters seem to rank right up there with black holes and UFOs on the Mysterious Objects List. But once you know the basic, choosing the right converter isn't mysterious at all.
BUILDING THE PROPER ENGINE: A torque converter reacts to engine torque; the more torque you feed a converter, the better it will perform. For a converter to operate properly, you need to build your engine to make as much low and midrange torque as possible in the same rpm range the converter is rated for. For street engines, this means limiting camshaft to no more than 230 degrees at .050" lift, advancing the cam 2-4 degrees, and using a small cfm carb. when possible.
STALL SPEED: Nothing about torque converters is more misunderstood than stall speed. Stall speed is directly related to the amount of torque your engine produces - the more torque, the higher stall speed. For example, a converter with a 2800 to 3200 rpm rating might provide approximatley 2800 rpm of stall speed behind a mild small block V8, but about 5000 rpm behind a big block making 800-plus ft.-lbs of torque. Without knowing how much torque your engine makes, you cannot know how much stall speed a converter is capable of.
That leads to perhaps the biggest problem people have when buying a converter: stall speed ratings. While most converter manufacturers list stall speed ranges, those numbers are very, very general guidelines; true stall speed is impossible to measure due to vehicle variables. The time-honored method of testing a converter's stall speed-holding the brake and revving the engine while in gear-doesn't work, primarily because the tires will spin before you reach the converter's stall rpm.
Most complaints about converters center on a stall speed that is too low. The problem is usally a lack of low-end torque, but there are other variables that can contribute to lower stall speed, including the following: *Low vehicle weight *Small cubic inch engine *Very low compression ratio *Tunnel ram-type manifold *Large carburetor thtottle bores *Mechanical secundary carburetor linkages *Multiple carburetion *Long duration camshaft *Retard cam timing

[Christer]

Thanks! I think I need to study this subject more closely. I will be back with more silly questions.

[Christer N (Christer)]

If I say that the converter works as a
1) clutch
2) hydraulic gear with rates that varies from 2:1 to 1:1.
Do you agree with me or not? Are they the two main functions of a converter?
(I have got this facts from a book)

[Daver (Daver)]

Well yes. Of course it works as a clutch but I could never get my head around stuff like torque multiplication. I know enough to use the right one but I don't need to know how to design one!

[Christer N (Christer)]

Maybe it is unnecessary knowledge...but it is intresting to test new ideas and see what comes up,
on this superb discussion board.

[Daver (Daver)]

Nothing wrong with understanding the basic physics involved. It is just too much for my thick head!

[Christer N (Christer)]

I think you underestimate yourself!