I recently bought a 98 12v with and automatic tranny. It has #5 fule plate and 370 injectors and a new rebuild on the tranny with an upgraded torque converter. It also has the waste gate blocked off. It is a goes through the gears ok but when it drops into overdrive it just takes off. Would like that power through all the gears. What is making it act this way. I know it is overfueling and i need to do some more upgrades and increase the timming. can any one tell me what might be going on?

 

Most likely your tranny is slipping until it hits overdrive, turning HP into heat rather than forward motion.

 

That kick that you are feeling is the Torque Converter locking.

 

Put a lockup switch in it for the TC.

 

how hard is it to put a torque converter switch. and how does it work? It is suppose to have a after market turque converter with 40% more lock up. Is there an adjustment to the tranny i can do?

 

Very easy. Instructions here http://www.tstproducts.com/Torque%20...p%20Switch.pdf

 

how will the truck run with the switch turned off?

 

It will run the same as always. You'll just able to lock the converter in second gear. Is there an upgraded valvebody in also?? If not I'd be looking into doing something soon to keep your tranny intact.