mating a 81 3b motor to a 78 bj40 transmission (2 Viewers)

[mike]

I trying to replace a bad motor in a 78bj40 with a good motor from a 81 bj42.
Will a 81 3b motor mount directly to a 78 bj40 transmission? If so, which year clutch, pressure plate, throw bearing and slave clutch cylinder would I use? Would any modifications be required?
Thx Inadvance

 

[lowenbrau]

The tranny will bolt right up. Use the clutch, T/0 bearing etc from the '81

The throttle body is different and will require some monkeying with the throttle cable. It might help to turn the 3b throttle body 90 degrees or swap the one off the B as long as it seems to be as big.

I think there is something else but I can't think of it.

 

[mike]

I should re-use the 81 clutch, 81 cover & pressure plate, 81 release bearing, and the 81 slave clutch cylinder. Everything should bolt right up and the clutch should function properly. Is there anything else I should be concerned about before I go ahead and swap the motors? Thx

 

[crushers]

the exhaust manifolds are different so you will need to use the 3B manifold and a new exhaust is a good idea, i recommend a 2 1/2" aluminized with a quiet free flowing muffler.

 

[mike]

Should I be concerned about the motor mounts positions? Thx

 

[crushers]

if memory serves me right it is a straight bolt in...

 

[mike]

Which bell housing and slave clutch cylinder should I use? Is there any difference between 81 and 77 parts? Thx

 

[lowenbrau]

Use all from one or all from the other. I'm pretty sure the parts are interchangeble anyway.

 

[crushers]

as Bruce said, all of one or the other but i suggest going with the newer parts since you will probably be able to source parts longer...