1986 monte carlo ecu wiring question! HELP!!!

ThomasH90

ThomasH90

n00b
Jun 24, 2020
3
1
Alright so i have a 1986 monte carlo. The person before me swapped a 350 from a 1975 c10 into it. During this swap they just flush cut the wire harness going through the fire wall. How screwed am I? the car runs as is now but how much of that do i still need? Or how much of it can i get rid of? its a carbed motor at this time.
 
M

mc1984ss

Not-quite-so-new-guy
May 18, 2020
29
3
When I first replaced the factory 305 input in a 350 with. Holley carb. I ditched the factory carb and computer. I removed all the uneccesary wires going to the ECU. I cut the ECU harness at the firewall just to make removing it easier. If it's not the factory computer controlled carb you will not need it. All the necessary wires needed are left behind. Mostly out of the bulkhead on the firewall. On the other hand if you wanted to return it to stock and run the factory carb and ECU then you have a major project.
 
ThomasH90

ThomasH90

n00b
Jun 24, 2020
3
1
It won’t ever go back to stock 305. And this was tbi was it not? Either or I’m using edlebrock 1405. I just didn’t know how much goes to rpm, dash crap or if I can pull the computer out all together
 
UC645

UC645

Master Mechanic
Apr 20, 2020
268
93
Kittanning, Pa
It won’t ever go back to stock 305. And this was tbi was it not? Either or I’m using edlebrock 1405. I just didn’t know how much goes to rpm, dash crap or if I can pull the computer out all together
The computer can be tossed if you’re not running a TBI unit or feedback carb. You’ll also need to grab a different distributor if the one you have is a computer controlled type.
If you’ve got the pockets, grab a do it yourself harness from Painless Performance, and rewire the car. That’ll run about $210 to $270, IIRC, more expensive harnesses just have more provisions for accessories.
 
M

mc1984ss

Not-quite-so-new-guy
May 18, 2020
29
3
If I remember correctly almost if not all the wires that go through that huge grommet on the passenger side do not get used if ECU is discarded. There may have been some wires that passed through the same grommet that didn't go to the ECU but none that I can remember. All of my power wires and ignition wires come out of the factory bulkhead connector under the booster. The tach wire has that little cylindrical filter inline. I can't remember where the tach wire passes through the firewall but I do know there is a connector behind the radio. Follow one wire at a time. If you ever doubt it unhook it and see if the car still runs and everything functions. Check out there are heat factory wiring schematics over at Malibu racing.
 

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