Trans takes a lot of RPM to move

[Schmucker]

I just swapped a 200-4R in my '77 Corvette and I tried to drive it today. It rolls fine in reverse. When I **** into and forward gear it takes about 1700-2000rpm to get the car to start moving forward, and it barely wants to move then. According to the trans code it originally came out of an early 80's Monte Carlo, but it was resting in a Grand National when I got it. It doesn't appear to be a D5 converter. It was rebuilt at some point.
Fluid level appears okay. What I'd like to do is get a pressure guage (any links to a cheap one?) and check the TV linkage pressure. I adjusted it according to the directions with the level just on the pushrod with the throttle closed and with it fully open at WOT.

So, too much RPM to get the trans to drive in drive.
What I think to be possible problems
1. TV linkage/pressure
2. Something interal in the trans
3. Torque converter

The first one seems to be the most likely. I tried all the forward gears so it can't be the shifter linkage.

 

[chris718]

lets check convertor stall speed with the brakes applied.what is it?does smoke come out of the filler tube when you do this?

 

[Schmucker]

Well, I added another quart of fluid (it was low, but it did read correct before, no idea what happened that it showed low, but whatever) and it rolls fine forward with no throttle and just in gear. I backed up the hill and it went okay and didn't sound like it was slipping at all in reverse. I put it in 3rd and drove around the block. It seemed to drive fine. It shifted at a normal rate. It was sort of soft, but it seemed fine. Probably how it should be for the Monte Carlo it came out of. I applied about half throttle and it seemed like it increased in RPMs but didn't pull proportionly. So I assume some slippage occurred. It was only turning about 1200rpm in the 25-30mph range. This is the stock L48 in the car making about 200hp/300ft-lbs with the opened exhaust. I'm going to check the pressures tomorrow. I need a couple more fittings to get the gauge set up. So, if the pressures check out okay at minimum TV and maximum TV (and I'm confident I have my TV linkage set where it can reach maximum TV through the carb as I set it with the pan off so I could see the plunger position and everything. So if the pressures are okay, we can assume the torque converter is okay (no smoke, seemed to want to start moving more at around 1300rpm) but if the slippage continues when decent throttle is applied, would it be time for a rebuild, or should I pour a bottle of seal rejuvnation stuff and drive it for the rest of the year? The trans has been sitting 1-2 years without use.

 

[Schmucker]

I didn't drive it because it's raining, but I added yet more fluid (it's a BOP dipstick tube in a Chevy engine, that might be why I screwed up) but anyways I checked my TV pressures. They seemed to be all okay. Maybe just a hair on the high side at full TV, but I don't think that that is a bad thing. It reads in the higher part of the range at minimum TV, but still within the range. I think I'll be okay.