hey , im 16 and i know a bit about cars. i just bought my car its a 350 with stock heads an aggresive cam, edelbrock performer rpm intake and a holley 600 vs carb. the rear end is a 10 bolt with 3.42's and he said there was a stall coverter. what exactly do they do and how can i tell what rpm it is???



thx for all the help

 

all converters are stall converters just like all engine are cubic inch engines or gear sets are ratio gears. you can tell what or close to what stall you have by mashing the brake and the loud pedal at the same time ,your stall speed is the rpm where the car either has to move or die

 

OK, here's a crash course in stall converters (magic box seen by most of us ;-)).

A manual has the clutch to engage at stops to keep the motor from transfering the power threw the transmission to the rear end and to the wheels.... without it 2 things can happen... 1.) motor is overcomed by the brakes and will stall (die) or 2.) motor will overcome the brake and won't stop.... either one isn't good

For automatics the stall works in the same way. When you come to a stop it magically starts to spin without putting all the power to the transmission. Thus letting the motor sit and idle with the transmission in gear. The stalls will eventually start transfering close to full power to the transmission at the a certain speed (stall). They will still slip and move a little bit below the stall rate. Which is an important fact most people think if they have a 3k stall they can't get off the line without turning the motor to 3k to move (that is wrong).

We can all discuss the OEM ones all day long and not come up with one rate... lets just say it's a 1000 rpm stall. Ok so when you stomp on the gas (all the way to the floor) it doesn't transfer power till it hits 1000 rpms motor rate. Then the power goes transmission then to rear end then to the ground.

Aftermarket ones come with much higher rates anything from like 1600 all the up to 5k+ stalls. I have a 2400 stall in my stock 350. I mash the gas and it's like I just dropped the clutch on a manual at 2400 rpms and I take off.

Another factor the stall plays is it's a multiplier for the tq produced (more tq will help you move, if you get traction). The factory ones are around 12" diameter aftermarket ones are 10 to 9" you can find a lot of different sizes... the smaller the better. The less stress you will put on the transmission (cause of the less weight the motor has to fling and hit the transmission input shaft with). Also the smaller diameter the more of a multiplier you will have.... say a stock converter 12" has a (1.5-1.75) while the new 9.5" converter has a (2.2-2.5). This gives you a little more tq off the line.

So if you're motor tq at the launch speed would be mulitpled by the factor.

Also another topic all together is how the stall rates are figured by the manufactures... I'll leave that up to you to use the search function and figure that out... since it will probably just confuse you and me more.