replaced transmission and now no acceleration or downshifts

[ryan78]

I have a 78 scout2 with 345 and 727 and rochester 4bl , I had the trans rebuilt due to a cracked tailshaft housing that caused a massive leak and damaged trans. I reinstalled trans and it runs and drives but when I first tried to star it I noticed I had pushed the kickdown linkage up and jammed the throttle linkage. I had to take apart the linkages and re install them the way I saw to be correct, now it seems like the throttle pedal doesent have enough throw to it and when u drive the truck and floor it it only accelerates slowly, but does upshift but at low rpms it doesnt downshift when u floor it either. I am not sure if its a throttle linkage prob or kickdown issue. If I put the pedal to the floor and grab the throttle linkage by hand I can pull it back another inch or so it seem like the 4bl arent even gonna open at all. Any info would be greatly appreciated thanks

 

[Michael Mayben]

I have a 78 scout2 with 345 and 727 and rochester 4bl , I had the trans rebuilt due to a cracked tailshaft housing that caused a massive leak and damaged trans. I reinstalled trans and it runs and drives but when I first tried to star it I noticed I had pushed the kickdown linkage up and jammed the throttle linkage. I had to take apart the linkages and re install them the way I saw to be correct, now it seems like the throttle pedal doesent have enough throw to it and when u drive the truck and floor it it only accelerates slowly, but does upshift but at low rpms it doesnt downshift when u floor it either. I am not sure if its a throttle linkage prob or kickdown issue. If I put the pedal to the floor and grab the throttle linkage by hand I can pull it back another inch or so it seem like the 4bl arent even gonna open at all. Any info would be greatly appreciated thanks

Your description tells me that the throttle pressure control function of the valve body is crapped due to some sort of mechanical damage which occurred when you messed with the linkage. The valve body is going to have to be removed so that it can re-assembled/repaired correctly. At the same time, both seals used with the shift tower need to replaced. I've covered the process in detail in other threads in this same sub-forum.

Once the valve body is repaired and re-installed, the throttle cable travel/adjustment must be corrected first so that the carb throttle lever returns to a solid idle position and opens the throttle lever completely at wot. Once that is done, then the "kickdown" adjustment/verification is performed, that is two separate operations!

Since you stated you have a rochester 4v carb, it must be a quadrajet which is an "air valve secondary" carburetor. It's near impossible for the secondaries to actually actuate unless the vehicle is in motion and under enough load to operate the vacuum pulloff to allow the secondaries to actuate, that can't be down with the vehicle stationary in most cases. You May be able to see secondary actuation slightly when not moving but you will have to open and hold the throttle to allow a low manifold vacuum condition and high air flow through the carb air horn.