hotcoupe

I have TH400 hooked up to a slightly modified 350 small block. When i'm cruising down the road the engine r.p.m. is 3000 and the car speed is 45 m.p.h. The rear axle ratio is a 4.10 in a 12 bolt. The rear tires are 25 1/2" in diameter. The torque converter was a B&M 2000 stall (unknown model). In an attempt to fix my problem I changed over to a TCI Saturday Night Special. The torque converters are not the lockup variety. I've checked the axle ratio 3 times now and it definitely is a 4.10. I checked the car speed twice by running the car past a radar detector on the side of the road and it indicated 45 and 46 miles per hour respectively. I'm certain that the engine is turning 3000 r.p.m. because it is both screaming and at the same time everyone is passing me. I've run the calculations manually and thru the calcs on the internet and both come up with a slippage rate of about 20% to 24%. It positively hooks up in first gear and appears to have no slippage in third gear when I hammer it. I checked all the gears relative to the actual car speed and they all seem to be proportional to their ratio. Now that were in the warmer weather I had to add an auxiliary fan to keep the whole system under 200 degrees. I've contacted B&M, TCI, several other torque converter manufacturers and numerous transmission shops in the area and no one has come up with a logical reason why the engine is turning so many r.p.m.s. Does anyone have any thoughts or ideas as to why this is occurring.