I have an 87 formula w/ a 700R4.When I bought the car the guy said the tranny was rebuilt.I can see evidence of tranny work so I don't doubt him,maybe not rebuilt but replaced.Anyways I drove the car for about 1 1/2 years with no problems,real strong w/ nasy 2nd gear scratch.I pulled the worn 305 LG4 out and dropped in a very mild 400sbc tpi.I had gotten into a fist fight w/ my brother and decided not to live with the low life.This just happens after I pulled the 305.Then the car had to sit at my grandma's house for 4 months.Now the 400 is in and my tranny is slipping bad.My fluid level is good but shows some discoloration.Probaly due to old fluid on need of change.I can read fluid fairly good.My t/v cable is adjusted correctly .My tranny slips bad but if I manualy shift it then it has no slip at all.I guess the tranny is just going south and can't handle the torque of my 400.But I would love to know why it works fine manually shifting?

 

In the Man1 and 2 posotions you have max line so that could be masking a problem. Best bet now ouwld be to get a pressure gauge on it and see what is going on. It sounds like either the TV isn't responding properly leading to a slip or as you stated the 400 may have pushed it over the edge. Do you have the proper induction setup so that the TV geometry is correct? This is critical.

 

Yes I have all the right stuff for tpi,I got everything from the j yard.If I get the tranny guage what to look for?Its feels like when I go more than 20% throttle from Idle It goes out of gear mid way through 1st.Would the clutchpack be the cause?

 

If you get a gauge on it record readings in all positions at these speeds: Idle, Fast Idle and Fast Idle W/TV pulled to max. Also if possible resord readins as problem is occuring.