Hello everone. I don't post much I am usually a lurker ,but I can't seem to find an answer here by searching. My computer is also running slow or somethings up with the site. So I figured I would ask. I did a T.P.I swap on my 52 truck with a 700 r4. I switched the motor from mass air to speed density and bought a rebuilt trans from GM. I ordered for a 1990 if that makes a difference. I am running an s10 4x4 rear I believe 3.25 gears not positive. I am having a problem with the convertor seems like it's locking up early. It seems to bog down at abou 40 mph (my speedo is broke right now) . I figure it's the convertor cause if I just tap the brake the problem goes away or if I even just keep light pressure on the brake pedal it will be fine. I am thinking I have the wrong speedo gears in ther and the computer is getting the wrong speed of the vehicle and locking it up to early. The speedo cable broke . It did work for a little while and I noticed that the gauge (dolphin gauges) would be reading way faster than I was going. I appreciate the help
Dave

 

my 86 305 tpi with a 700r4 tranny did this, turned out there was a tsb on it i found through work. Said there was an updated prom to prevent the converter from locking up too early, so i got the new prom and it fixed it....dont know if thats your problem, but maybe. I am not sure how many years were affected.

 

I will have to check. I actually have a piggy back prom on there that I bought from tpi parts. I will call them and see if they ever had this problem. Thanks.