The P.O. said the 700R4 was "built". I know nothing other than that. 350 TBI w/ 3.42 gears. The thing is so mushy under 2000 RPM it drives me nuts. I cant even keep it under 1500 RPM if I'm trying to drive, it shoots right on past with any decent amount of throttle. RPM drops by several hundred, sometimes up to a 500 RPM drop, when the TCC engages.

My 3.1 does more between idle and 1500 than my LO5 does. I do have 1-3/4" headers, but do they really kill that much torque?

 

If you know the brand and can get a serial number off it, you can contact the manufacturer and ask for information about it. Chances are it's an off the self model.

There's little to nothing you can tell about a converter just by looking a it.

 

Does my description sound like that of a car that has a higher-than-stock converter? Perhaps too much converter for such a low-RPM based engine? I simply lack the experience to be able to tell. I figure I should be able to put around a parking lot 1000 - 1100 RPM no problem, but It's just not so.

PS - My stock tach has been fixed, calibrated, tested, and is accurate.

 

Sounds like a cheapish large-diameter converter with slightly higher stall than stock.

 

A lot of performance can be found in a converter. The torque converter should be matched to the camshaft for best performance however many people want that high performance engine but don't like the high rpm required with a higher stall converter. A "stock" camshaft should have a converter with less than 2000 stall. The idea of stall speed is to get the engine into it's best operating range quickly. A converter that stalls too low will lug the engine down as it tries to build up to it's operating range. Too high and the engine revs above it's useful powerband. Driving around at low rpm with a high stall converter builds a lot of tranny heat because the converter needs to slip at those lower rpms.

The only way to know the true stall speed of a converter is with a transbrake however a flash stall can give a rough idea of what it is. From a dead stop, mash the throttle and watch the tach. The tach will jump up to an rpm before the car really starts to move. You can also try a brake torque stall test but the vehicle's brakes won't hold the car back before the converter reaches it's stall speed. My converter stalls at 6000 and I can barely hold the car with the brakes at 4500.