is there any difference in stall speeds when choosing a torque convertor for a big block? i heard somewhere that a 3000 stall is different in SB's and BB's. i have a cam with an RPM range of 2500-6500, and was looking for one somewhere around 3600-3800. can anybody clear this up for me?

 

Converter stall speed depends on the amount of torque put out by the engine. Because of the longer stroke, a BBC will produce more torque at lower rpms than a SBC.

The rated speed given on a torque converter is only a rough estimate. A converter that's rated for 3000 stall may only stall at 2500 behind a SBC but could stall at 3500 behind a BBC. It all depends on the amount of torque going into the converter. A hopped up SBC could also stall higher than a stock BBC using the same converter.

The only way to know the true stall speed of a converter is with a transbrake. The vehicles brakes can't hold the car enough to let the converter come up to full stall.

My 8" converter is rated at 5700 stall. Before I did a cam change it would only stall at 5000 rpm. The tranny was slipping so I haven't been able to recheck the stall speed with the new cam.

Altitude will also affect stall speed. A vehicle at a higher altitude will stall lower than the same vehicle at a low altitude. If you live or constantly use your vehicle at higher altitudes, such as Denver, you would want a converter that stalls a bit higher than what you would normally use.