i've got a f700 - i put in a 460 engine and took out a 370 engine. new engine works great but can't get going any faster than 50 km/hr. seems my automatic transmission is not working right. i have to rev it to 35rpm to make it shift. anybody have any ideas on what's going on? i was thinking maybe low transmission fluidbut turns out that's not the case. i do also have a low and high axle gear on this. i have no idea where to look. any advice would be greatly appreciated! thanks.

 

Well, I don't know what transmission you have, but I'll assume something like a C6.
2 things come to mind affecting shifting.
1. Missing or disconnected vacuum modulator line
2. Throttle Kick down linkage disconnected/binding/mis-adjusted

 

Thanks Dailtone that was it!!! disconnected vacuum modulator line

 

Any time. Glad to help.