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85 GT convertible
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Discussion Starter #1
I have searched for days and found very little info on my car. I have a 1985 Mustang GT convertible AOD car. I found out 85 was the first year for roller cam. Good news, but I have an auto car. In 85 manual cars got the Holley 4180 series carbs, but the auto cars got the CFI injection. I need all the info on how to convert the CFI to carb. Of course I know that I need a carb intake, I'm choosing the Edelbrock Performer RPM Air Gap. I will also get a 600CFMish Quick Fuel technologies carb.

My questions are what is the factory fuel pressure for the CFI? Do I have to switch fuel pumps or just put a regulator on it? I noticed the fuel hoses at the intake are different. What do I need? Also, do I have to do anything about the engine EEC? How much does the CFI EEC have control over?

I also plan to pull the smog pump and put a smog delete pulley on it. How much can I get rid of after that? Can I delete the EGR and smog tubes etc? Will that effect the air tube going to the catalytic converter in a bad way? I kknow I have a lot of question but I want to learn fast. I'm excited about my car. I just got it a few days ago. Please hurry with info. I have to feed my addiction....lol Thanks.

Jerry
 

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Exhaust fume addict
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1,526 Posts
If you are going carb I think all the emissions and engine wiring harness can go. I think you may need a different distributor though. I haven't done a carb swap on one of those so maybe someone will chime in that has
 

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85 GT convertible
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660 Posts
Discussion Starter #3
Thanks for the quick reply. Keep em coming folks. I don't mind changing the distributor. I was thinking an MSD billet and a 6AL box at least, if not a Digital 6 box. I wonder how many sensors have to be put back in the carb intake. I just bought a Chilton book but haven't found 85 specific info for the CFI. I want to learn this in depth, and parts collection so I can tackle this in a weekend. It's still my daily driver.

Jerry
 

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I'm almost positive that the only 85 mustangs that received the roller motor was the carbed ones and not the CFI ones.
 

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The 84-85 CFI motors were flat tappet cam engines. Professional Products makes a return style fuel pressure regulator to knock the fuel pressure of the EFI pump down to 7psi or so for carb use. You will also need a carb type distributor & box along with a intake & carb.
 

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85 GT convertible
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660 Posts
Discussion Starter #6
Thanks for the replies. Bad news on the cam. I guess I'll be changing that too. I'll check into the regulator.

Jerry
 

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I yanked my "computer" along with all the wiring, mine was carbureted though.
For mine all it controlled was the emissions stuff, I heard it would run with it unplugged.
most likely controls everything on yours. Fuel, idle, emissions, maybe timing

Id do the digital 6AL box for the easily adjustable rev limiter. I love mine
Only sensor youll need in the intake is water temp
 

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85 GT convertible
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660 Posts
Discussion Starter #8
Oh, you also said I need a carb distributor andbox. Does that mean an EEC for carb engine? Can I run a stand alone MSD box and distributor? Would I get rid of most othe wiring? Trying to get a good mental image of the project, and collect parts.

Jerry
 

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Oh, you also said I need a carb distributor andbox. Does that mean an EEC for carb engine? Can I run a stand alone MSD box and distributor? Would I get rid of most othe wiring? Trying to get a good mental image of the project, and collect parts.

Jerry
It was called the ECA for the carb engines.
No need for it

Just get an msd box and plug it into the dizzy, wire the keyed 12 volts, + and - , tach, and coil wires.

Taking out the wiring will take more than a weekend. But once you get it running you can slowly knock that out.
 

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My old 85 gt ,carbed ,5 speed would run with the computer unpluged... so yes mab, you heard right
 

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85 GT convertible
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660 Posts
Discussion Starter #12
Sounds good guys. I'll start with the RPM intake and QFT carb. Then I'll get the MSD billet distributor and the Digital 6AL box. I'll pipe plug any outlet in the new intake that I don't need and get the gaskets. I'll get it running and start looking at a plan of attack for the wiring harness removal stuff. It should be fun.

Jerry
 

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You should upgrade multi port fuel injection. And get the wiring harness from an 86 gt then covert it to mass air
 

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85 GT convertible
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660 Posts
Discussion Starter #14
I would love to ranw, exactly what would I need? Could I buy a brand new harness from a company or have to salvage one, and where would I salvage one? I would rather buy new.

Jerry
 

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upper intake, lower intake, throttle body, maf, wiring harness, injectors, computer, new fuel lines and pump to support efi. Too much money imo. For all that money you could make it faster with a carb
 

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85 GT convertible
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Discussion Starter #17
I wrote down a parts list for both carb and EFI. Then I compared prices from Summit, Jegs, and a couple others. I even found the plug and play wiring harness. The prie came to around $2,305 for the EFI conversion and $1,150 for carb conversion. I think I will go the carb route. If I go the blower route in the future maybe I'll do a single carb 177 roots under a 4 inch cowl hood.....lol

Jerry
 

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You can buy parts used. And the wiring harness id get straight from an 86 stang. Yes, a carb swap will be cheaper no matter how you add it up. But i still say EFI
 

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what are the plans for the car anyway lol?
 

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If you are considering efi, if boost is in your future I would be, you might consider just buying a donor car. Around here you can find them for a couple grand, with no title, or bad body. Upgrading to a roller motor, and a 8.8 rear, could make it worth it in the long run. With the automatic , even with bolt on upgrades, carb or efi, you would be lucky to hit 200 rwhp with your current motor, imo.
 
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