I have a 1989 F150 4x4 with the 5.8L 351w EFI and c6 tranny. I recently picked up another 351w EFI out of a 1993 Bronco that had already been built; Comp cam, roller rockers, gt40p heads, shorty headers, MSD 6a ignition, etc and I'm running into a few issues with the swap.

The first has to do with the wiring harness. The motor came with a wiring harness, but the plug for the main harness is completely different (one large plug as opposed to four smaller plugs on the truck). I figured I'd just use the harness from my truck and the stock motor, but the electrical plugs for the distributors are different. I've found one other person that ran into a similar issue, but it was reversed (trying to put an old style distributor in a newer truck), and he was told to exchange the distributor he just bought. Are there any harness adapters to adapt the stock harness for the new distributor? If not, is there a way to splice the plug from the harness that came with the motor to the stock harness? I would prefer not to have to change the distributor unless absolutely necessary...

Also, the smog equipment on the stock motor screws into the exhaust manifold, which poses a problem with the aftermarket shorty headers since they don't have the same hole to screw it into. Will not hooking the smog equipment up cause any issues (outside of the illegal emissions...), or is there some other way to hook this up other than to the headers? The guy had this engine running in the Bronco the way I have it, so he didn't have it hooked up to the headers...

I'm still somewhat of a noob when it comes to serious mechanical work, I've always been more on the body/paint side of things. Is there anything else I'm going to run into a problem with that stands out to you guys? Thanks in advance, any help is greatly appreciated!

 

You can't use any of the wiring from the donor motor.. as you have already figured out, but the distributor from your old motor will plug right into the '93 block so that is what you should do. The smog system connected to the exhaust manifolds indicates this motor was originally from a heavy duty truck, but that's of no consequence really and the whole system can be eliminated without upsetting the computer. Remove all the plumbing and valves around the back and on top of then motor that is connected to the air pump, and plug the vacuum lines attached to the TAB and TAD solenoids beside the coil. You can remove the air pump as well but you'll need a shorter serpentine belt, alternatively you could leave the pump there as an idler and attach the exhaust muffler directly to the pump output to dampen the noise it makes, that way you don't need another belt.

 

So there's no way to splice the plugs I guess? Since I still have both motors still complete sitting beside each other, is eyeballing the position of the current distributor going to get my timing somewhat close? This is all new territory for me, I've never swapped distributors or had to mess with the timing on a vehicle. I know the guy I got the motor from said that it has timing gears in it, not sure how/if that affects anything...

That's what I wanted to hear about the smog equipment! I was afraid it would mess with the ecu and cause it to run too rich or too lean if it wasn't hooked up.