1991 F-150 XLT Lariat 4X4 Engine Change
 

I have a 1991 F-150 XLT Lariat 4X4 that I got out of North Carolina and it currently has the 5.0L engine. It has never really had much power and has also had a piston replaced before. I got a 1990 F-150 pickup, (not a 4X4) and it has the 5.8L engine. I was told it is a windsor. Both are automatics, and I am wanting to rebuild the 5.8 and place it in my truck. If I am not mistaen, the transmission bolt pattern is the same, and everything else is same except piston size. Is this possible to swap these engines and use the 5.8? I have the complete truck, and now would be a good time to keep what ever else I may need. Any thoughts or suggestions are GREATLY appreciated! :-drink

These two engines share very little in common actually, the 5.8 block is taller and wider and much more durable but the good news is it uses the same engine mounts and trans bolt pattern so it will physically bolt in where the 5.0 was. You will need the complete 5.8 motor and you will have to determine exactly what transmissions both trucks have because there are 4 different automatics that could have been used, the trans code on the drivers door calibration decal is what you need to find and then compare it to the codes here.. Ford Axle Code Chart .: Articles
Now if you're real lucky both trucks will have the same trans but even if they don't you can make the engine swap work with the correct flexplate, and if you have the worst case scenario where the 5.0 truck has the 4R70w the job is still possible but you're gonna have to use the trans attached to the 5.8, and that's because the 4R70w is computer controlled and it was never factory installed behind a 5.8 so there are no compatible PCMs for it. In any event I have had both of these motors in my '90 so I can help you out with the details, just figure out what transmissions you're working with and we'll go from there.

Ok on my 1991 XLT Lariat 4x4, the trans code shows a T and on the regualar longbed pickup, its a 1990 and it has an E. I don't see a T in that chart, but i do know its a 4 speed automatic with overdrive. This is on the 1990 truck.
http://www.dawghowse.com/images/stic...F150pickup.JPG

And the 1991 F150 XLT Lariat 4x4 has this one

http://www.dawghowse.com/images/stic...991f1504x4.JPG

OK you're in luck, the '91 has the all mechanical AOD trans so installing the 5.8 is as simple as buying a 28oz AOD flexplate for it, you cannot under any circumstances use the E4OD flexplate that is currently on the 5.8, the front-back offset is different and using it will immediately destroy the AOD transmission. With that done you then need to source a 5.8 PCM for a truck with a C6 auto(3-speed) or manual transmission, you cannot use the 5.8 PCM in the '90 because it will throw a mountain of codes without that E4OD trans connected, and moving that trans into the '91 is a big job since it will involve a lot of wiring.

Ok so the motor will work. Can't I just use the 5.0L flywheel because if memory serves me corrctly, at least in older models, everything interchanges. Meaning it would bolt to the 5.8 motor. And on this, you lost me. If mine is all mechanical, I won't have any electrical to plug up. Only thing I am interested in is changing the motor. Will I also need the computer from the 1990? Or will everything be the same? The motor in the 4x4 is the 5.0 and is VERY week to say the least. And by the way THANK YOU for all of the help on this. I really appreciate it. :-drink

NO everything does not interchange, Ford changed the 302 engine balance to 50oz after 1981 and the 5.8 is 28oz, and as I already explained the front-back offset of the flexplate is different for different transmissions so you cannot under any circumstances use the flexplate currently on the 5.8.


No you can't use the computer from the '90, it expects to see all kinds of sensor data from the E4OD trans and it won't see that in the '91 with the AOD, so it will throw a ton of codes and cripple the engine which is not what you want, so you need to find a different PCM like I described above.

Ok so to do this i need a 28oz flywheel for the 5.8 and also a PCM for the 5.8 with an AOD tranny. Is that what you mean? And any idea where I can find this stuff? I am gonna rebuild the 5.8 over the winter, then drop it in my truck in the spring so I have time to do it all.

The AOD was found behind the 351 in the mid '80s crown vic so you could order one of those from a parts supply house, and for a computer you'll have to search the junkyards and used classifieds for one from a truck with a manual or C6 trans since the AOD was never installed behind the 5.8EFI in trucks, but that doesn't matter since all 3 of these transmissions are not computer controlled.

Ok found the flywhhel at Autozone for 49.99 and its 28.2oz so it should be the one. http://www.dawghowse.com/images/stickers/flywheel.jpg

Also I can by the ECC (Engine Control Computer) for 99.99 and up for a 1991 f150 truck, but nothing lists for a PCM. Is this the same thing?

Found several on Ebay for 85.00 and up

<center> <table width=""> <tbody><tr> <td style="text-align:center" width="100%"> 1989 1990 FORD TRUCK 351W C6 ECU ECM PCM E9TF-12A650-AF1A E9C 5.8L AT COMPUTER</td></tr></tbody></table></center>

Is that flywheel listed specifically for an AOD?

I can't follow the link for the ECC but the description looks correct.

It doesn't say on the site, but I looked up a 1986 LTD Crown Victoria and that's the one it showed me. And the ECC and the PCM are the same thing right? And also. do I have to use the wiring that's on the 5.8 as well? I left it all connected when I removed the engine this morning, and its all on the motor.

I tried to send you a PM, I couldn't find a PM box. I have a ECC for a '90 F250 w/ a 5.8 and a C6 auto trans, it's just sitting on a shelf collecting dust. $50 shipped and it's yours. I'll guarantee it to be good. :-X22

Should be the right one then.

Yes.. different terms for the same thing.

No, remove the upper intake and disconnect all of it, do the same with the 5.0 when you pull it out and then reconnect the 5.8 to the stock 5.0 wiring when you put it in. The reason for this is there is no guarantee the harness portions are pinned the same or that they even use the same connectors.

Sounds good to me!