Lock up converter - not feeling the love

[gwcrim]

The ride:

1980 C10, mild roller 400, 200-4R, 2-2200 converter, 3.73 gears, 27.5" tires. Nothing fancy or unusual.

I thought when I had the trans built that it would be nice for fuel economy to use a lock up. It's wired through the brake switch, then to a toggle switch, then to the vacuum switch. When I drive the truck around w/out the converter on, it feels decent enough. When I let the converter lock up, it acts in a way I don't like. From very low speed, it shifts into drive pretty quickly, then the converter locks up, then it downshifts. From a 35-45 mph cruising speed, if i accelerate up a small hill, the converter locks up and the RPMs fall badly.

Is this what I should expect from this set up?

Any tuning tips or other words of wisdom?

-Crim

 

[4WDKC]

I don't have a 200-4r or a vacuum switch but my 700r4 does not act like this.

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[74 Shortbed]

I ran my 700r straight off a toggle switch, lock/unlock whenever I wanted, just had to remember to unlock before coming to a stop, lol..

 

[yevgenievich]

It might need an adjustable vacuum switch and also wire it to come on only in 4th gear.

 

[gwcrim]

I'll explore the idea of an adjustable switch. How can I have it only engage in overdrive?