5.8 vs 3.8 T-Bird

[charliecrowe]

I have been in the process of changing my 1990 T-Bird from a nice comfortable 3.8 ,to a nice more compatible 5.8. However, as we all know there are always problems that we don't see until after things get , well almost all together. It seems that even though the origional 5.8 flex-plate fit the 1990 AOD torque convertor there is a problem with the extra 5mm that it sits back from the block ,which just happens to push the tranny pump back into the pump housing, which just happens to ruin the pump in a very short time, like about the time it takes to run in a new engine. Then when you put it in gear "the same tranny that you drove into the garage with" dosen't work any more.

This is when you are told that there is no way that this will work together,an old style 351 and a newer 1990 AOD transmission.

My question is: are there flex plates out there that will work in this combination?
1979-5.8 motor to a 1990 AOD transmission.

 

[tb9050lx]

I have been in the process of changing my 1990 T-Bird from a nice comfortable 3.8 ,to a nice more compatible 5.8. However, as we all know there are always problems that we don't see until after things get , well almost all together. It seems that even though the origional 5.8 flex-plate fit the 1990 AOD torque convertor there is a problem with the extra 5mm that it sits back from the block ,which just happens to push the tranny pump back into the pump housing, which just happens to ruin the pump in a very short time, like about the time it takes to run in a new engine. Then when you put it in gear "the same tranny that you drove into the garage with" dosen't work any more.

This is when you are told that there is no way that this will work together,an old style 351 and a newer 1990 AOD transmission.

My question is: are there flex plates out there that will work in this combination?
1979-5.8 motor to a 1990 AOD transmission.

basicaly it should fit fine sounds like u didnt seat the tourque converter right the bellhousings on the 5.8 and 3.8 are the same ,what year 351 are you using
?

 

[5.0ina66]

basicaly it should fit fine sounds like u didnt seat the tourque converter right the bellhousings on the 5.8 and 3.8 are the same ,what year 351 are you using
?

Agreed, there's no reason it shouldn't have worked. Unfortunately, I've done the same thing, almost fried a $3500 Nissan transmission before I noticed.

 

[squeak93]

I agree with above. I have a 74 351 with a 92 aod behind it. Runs just fine....


TC is not seated properly. Has to click 4 times before its in. At least mine did.

 

[squeak93]

Oh and in case ur wondering. I believe the last click is the one that drives the pump. Would very well explain why ur burned it up before leaving the garage.


Was it hard to install, I mean did u have to use the bolts to pull the trans the rest of the way to the block. Mine slid right up to the block obviously and the bolts were able to be threaded the whole way by hand then torqued at the very end.