Hello. One of my 87 Irocs has a delay of about 3 seconds when shifting wide open on the 1-2 shift. Car was originally a 305 tpi. has a 350 tpi now. When full throttle on the car it hangs in top of first for about 2 to 3 seconds and then shifts. Can this be a modulator problem or vacuum or... Trans shifts great otherwise. Thanks for any help. Car has untouched prom, mass air. Only mods are headers on this one.

 

I'm assuming this has the stock 700r4. First thing to check since you've had the engine out is whether the TV cable is adjusted properly. Have someone sit in the car and hold the throttle wide-open, then depress the button on the end of the cable and push the cable in away from the throttle body until it is tight, then release the button while still holding the cable tight. Did it show the behavior before the swap?

 

In my experience, stock 700R4's behave like this when up-shifted manually.

 

The cable is adjusted right. It wasn't when I got it. I got the car after the 350 swap was done.