Engine harness 3.8 to 5.0 swap

Topic: Engine harness 3.8 to 5.0 swap (Read 1713 times) previous topic - next topic

Engine harness 3.8 to 5.0 swap

May 20, 2018, 09:10:35 AM

Hey all, well after sitting on this for awhile, I think im going to do a 5.0 swap into my 84 3.8 car. I have a source for motor and tranny from either 84 or 85 burd, and hardware but unfortunately hes not selling the engine harness. How difficult will it be to get an ecm and harness? I was thinking of refresheninf the motor and asking you folks about what upgrades should be added. Will the 7.5" diff be ok?

Thanks
Russ

Engine harness 3.8 to 5.0 swap

Reply #1 – May 20, 2018, 09:27:34 AM

Check out CoolCats site. Lots of info on swaps, and more. Lots of knowledge here as well. Good luck with it and keep us up to date on how it goes.

Engine harness 3.8 to 5.0 swap

Reply #2 – May 20, 2018, 04:17:47 PM

Thanks will do. So what do u all suggest to make 250-275 hp from a 5.0? Easier to do carbed or efi?

Engine harness 3.8 to 5.0 swap

Reply #3 – May 22, 2018, 09:32:21 AM

So when I gutted my '83 for a carbed motor the EEC harness was not that integrated into the body harness. If that is the case on an '84 then I would highly suggest you gut the EEC harness out of the car and then use a Painless wiring harness for a Mustang 5.0 more specifically a 94-95 5.0 car (harness is a little longer). The Painless harness will be about $600 but it is brand new and stand alone so it would work really well. If I ever move over to injection on my '83 this is the route I will go.

Engine harness 3.8 to 5.0 swap

Reply #4 – May 22, 2018, 09:50:19 AM

Yep, have to agree. There's nothing like a new harness to work with. The cost is more but you get what you pay for.

Engine harness 3.8 to 5.0 swap

Reply #5 – May 27, 2018, 11:18:58 PM

Hey, if I use my 3 speed auto for now will it be difficult to hook up a kick down linkage??

Engine harness 3.8 to 5.0 swap

Reply #6 – May 30, 2018, 02:23:06 PM

Does the Painless harness come with a wiring diagram? Their instruction manual doesn't have one. From what I've read, the harness puts the SPOUT in the cab by the ECU and the TFI on the distributor instead of on the radiator (or maybe it's vice versa).

Are there any other plug-n-play EEC EFI harnesses? I like the idea of not having to use a 30 year old harness.

Engine harness 3.8 to 5.0 swap

Reply #7 – May 30, 2018, 02:37:49 PM

Also might want to check out Ron Francis for a wiring harness. Wiring and drawings are better than Painless if you decide to go with a new harness.

Engine harness 3.8 to 5.0 swap

Reply #8 – May 30, 2018, 03:43:22 PM

The Painless harness is labeled. I would describe it this way, if you have ever pulled the engine harness of a 5.0 EFI motor you can handle installing the Painless harness. The Ron Francis harness (awesome product) will be more OEM but I don’t think he builds one for a 5.0 Bird/Cougar. His are geared towards the Mustang OEM crowd. The Mustang harness is integrated into the dash harness as well as the separate O2, headlight, and alternator harnesses.

Definitely call them and see if he can do something for your car as he may very well build a stand alone harness. I’ve used the Painless harness a couple of times and it’s what you hear about the most on Cobra kit cars and the like or at least that is what I see.