Swapping 1994 4.o motor into a 1991 4.o, and need advice on problems or how to's

[denebutant]

I jsut got a used motor in very good shape (1994) the motor is a long block with intake, but the emmisions and other things are different. Im looking for some insight on problems or things to look for to make the swap easier. My original motor has 250,000 on it and is very tired. Thanks!!

 

[jimbo74]

it should be straight forward...they are the same engine

 

[denebutant]

I have the motor on a stand and did a side by side comparison on the emmision/intake and they are different. The used motor is a low milage "crate" motor out of a totalled truck. My motor is a stock 1991 with 250,000 on it and the emissions and said items are old, wiring is dried and brittle, so its not a direct swap. Im just not sure what to do ??

 

[BExplorer]

Check wirering

The wirering of the 94 will be different thus the emission component, maybe the computer need to be change too, but I'm not sure. Mechanicaly they are the same but electrically you would have to make mods or add thing to get up to 94 emission control. Maybe somone else here can hope in to help more!!!

 

[denebutant]

The motors long block is the same I think also. but does the 1994 distributor plug into the 1991 wiring??? The 1994 has an EGR in a different spot. The emissions are not a direct plugin though and I know that once I disconnect the 1991 stuff the plugs may crack or break since its old. Is there anyway to make the 1994 stuff work on the 1991??

 

[rpenner54]

You might as well get all the engine wiring for the 1994. Trying to hash together the 91 and 94 stuff is going to take up more of your time then just purchasing it. Especially if your current equipment is as bad as you say it is. Otherwise the blocks should be the same I would think. If thats the case then you should be able to re-use the upper portion of the engine again, but at 250k it would be smart to replace all that stuff. That way it will be like a whole new engine!