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Discussion Starter #1
Been trying to search this issue, but have not came accross the info I need, so here goes.
Am in the process of removing my computer controlled 1986 305, with the gauge package,ac, etc. After I get the 350 in, what electrical changes must I make? Totally eliminate the factory engine harness or rewire the engine? Sure need the experience of the members who have already solved this/these issues.
Thanks for your help and direction!
 

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I desmogged & decomputered my 86 305 . used same wiring , removed wires to carb & distributer & installed a EB carb & manifold & procomp vacuum distrib. On the temp gauge sending unit , the one on intake manifold is for the computer so you don't need it , use the SU near left front spark plug , I cut out all wires to computer , everything still works , lockup torque converter may need to be grounded but a/c & gauges all work .
 

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I desmogged & decomputered my 86 305 . used same wiring , removed wires to carb & distributer & installed a EB carb & manifold & procomp vacuum distrib. On the temp gauge sending unit , the one on intake manifold is for the computer so you don't need it , use the SU near left front spark plug , I cut out all wires to computer , everything still works , lockup torque converter may need to be grounded but a/c & gauges all work .
Yep then you will have an engine bay that looks like mine just a smaller motor.:alc:

 

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Discussion Starter #4
Thanks Chris Nelson. What about the tach hook-up? I thought it hooked up to the cc distributor? How would it be re-connected?
I assume you removed the computer box completely?
Sounds easy enough, just remove the wires not needed and re-loom the harness.
What about the SU on the steering box? Eliminate that also?
Yes, would love to have it looking like HKDUP87's! Maybe down the road some semblance.
Thanks
 

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The tech will hook up to your new dist. The one on the steering box stays. All the computer wires or harness are going to come out the passenger side firewall.
 

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The computer is one harness. The essentials to run the engine is another harness. Computer wiring all on the passenger side. Essentials on the drivers side.
There are wires that run from the fuse box/cruise control/ speed sensor across under the dash if you are wanting to completely remove the ecm wiring. You can just cut them over by the ecm and terminate them so they don't short out.
The tach will hook back to the tach terminal on the new distributor.
 

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Discussion Starter #7
Thanks, both replys significantly clarify my issues in the wiring. Can't be rocket science! It is great to be able to have access to the knowledge of the members.
 

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New B

:Welcome!: Wayne, Glad you found us. Have fun and enjoy NECOA. Nick's has a Jegs 350 and the computer is not hooked up, its a stand alone setup.
From Nick & Don
Grove City, Ohio. bowtie smile:newbie:
 

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To those of you who have yanked the ECM and harness, what are your plans for these parts? If you are tossing them out, I'd be interested in them. I have begun to dabble in modifying these ECMs by de-soldering and removing the old 24-pin socket and installing a 28-pin EPROM socket. This modification allows use of readily-available, erasable EPROMs in preparation of doing more tuning.

Let me know...thanks.
 

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I have begun to dabble in modifying these ECMs by de-soldering and removing the old 24-pin socket and installing a 28-pin EPROM socket.
Just a thought. I've been doing this tuning for over 14 years, and I use the ZIF socket and G1 adapter from Moates.net. If you do a DIY replace your socket, the ZIF socket still is a good idea, as it allows for quick change without damage. I usually swap in a chip maybe 10-12 times easily before I'm comfortable with a tune.
 

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Mike, I was wondering if that is what you had done. I have a Moates Auto Prom and installing a ZIF kind of makes sense. Also, a 28-pin ZIF enables data logging and zeroing in on the BEST tune for any particular engine setup.

My main use for another ECM and harness is to devise an old-to-new adapter. The adapter will enable me to use my 87 as I figure out any mysteries that may/will definitely crop-up.

Have you considered upgrading to a PCM, i.e., 8625 or 7427?
 

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Thanks pops for posting question.

I had some of my questions answered here and undergoing the same job that I should have done when the car was stripped of front clip and entire interior.

Being cautious because I don’t know the entire purpose of the ecm. Piecing together several wiring prints . I did find some wires that run down the passenger side not going to ecm. Concentrating on getting mine running again then continue with removing wires.
Dave
 

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Converter Lock-Up is simple. +12V Ignition on to brake light normally closed terminals to Oil Pressure Switch installed in 4th gear test port on side of transmission, to Solenoid Control wire in transmission case. Requirements for TC Lock Up are: +12V to Solenoid Control wire. Brake pedal NOT depressed, Trans in 4th gear. Pressing Brake pedal releases solenoid, other than 4th gear releases solenoid. This is standard set up for 700R4,2004R and 200C (except 200C is for 3rd gear).
 

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Pin D on the Case Connector is connected to ground. Since it needs to be added, I forgot. Pin D is not used in the computer control. Pin A is +12V conditioned.
 

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:Welcome!: Wayne, Glad you found us. Have fun and enjoy NECOA. Nick's has a Jegs 350 and the computer is not hooked up, its a stand alone setup.
From Nick & Don
Grove City, Ohio. bowtie smile:newbie:
So if I Dcomputerized, will my newly rebuilt Rochester still work? Or will I need a different carb and distributor?
 
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