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  1. #1

    Default 87 TFI to 1985 distributor wiring

    hi guys. Im confused. the more I read the less Im certain about how to take a 1985 5.0 5 speed dura spark set up and install it into a 1987 GT cv that I am retrofitting to carbed. Can anyone tell me which wires in the TFI set up I connect to the distributor, the duraspark module and do I leave the box coil alone? Also, what wires do I splice, or re-wire to get the electric fuel pump to run? Im going to use a pressure regulator with a return line.

  2. #2
    FEP Power Member Syco Stang's Avatar
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    You need an actual carb distributor. Not one with a TFI module, it won't work.
    1986 GT T-Top 5.0, waiting on trans and IRS swap.
    1988 GT Ragtop, 5.0, T5, 3.73, 03 Cobras with Nittos
    1989 LX Ragtop, 5.0, AOD, shift kit, Pony wheels, baby cam, X pipe and Flowbasterds.
    1984 SVO needs TLC

  3. #3

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    yea I know, Im using a 1985 5.0 5 speed distributor along with the duraspark module to replace the TFI, my problem is there is so much contradictory info on how to do this that I hoped that someone who actually did this can tell me the correct way. There is also the question of keeping the tach working.

  4. #4
    FEP Power Member Syco Stang's Avatar
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    Well, there is some cutting and splicing necessary if you want to use the Duraspark box or you could do the easy thing and get an MSD 6AL box. Easiest way to make this swap as painless as possible. I've done the duraspark bit before, and I don't remember specifics, but it took some work and a wiring schematic to get it sorted. If you're dead set on a Duraspark, you should get yourself the underhood wiring schematic for an 85 and also for an 87 and start splicing. With the MSD it will also be a one wire connection for the tach. Trust me, do an MSD and all will be well, it comes with straightforward instructions too.
    1986 GT T-Top 5.0, waiting on trans and IRS swap.
    1988 GT Ragtop, 5.0, T5, 3.73, 03 Cobras with Nittos
    1989 LX Ragtop, 5.0, AOD, shift kit, Pony wheels, baby cam, X pipe and Flowbasterds.
    1984 SVO needs TLC

  5. #5

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    Thanks for the input. I know some guys swear by the MSD's but at almost $500.00 for the set up the '85 distributor and duraspark module is the most cost effective way to go plus it's vertually bullit-proof and I have then in-hand. There has to be a way to do this

  6. #6

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    well I went to the MSD site. guess I can use my '85 distributor and just the MSD module. You're correct, pretty straight forward. 1 question? how do you hook the tach up? Do I need a tach apaptor or is there a way to wire it up?

  7. #7
    FEP Power Member Syco Stang's Avatar
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    You just need an MSD box which is no more than a couple hundred bucks. I think they're like $170 IIRC. You can use the Duraspark distributor with it. There is a one wire output on the side of the MSD box that you splice into the tach wire from the stock coil wire.
    1986 GT T-Top 5.0, waiting on trans and IRS swap.
    1988 GT Ragtop, 5.0, T5, 3.73, 03 Cobras with Nittos
    1989 LX Ragtop, 5.0, AOD, shift kit, Pony wheels, baby cam, X pipe and Flowbasterds.
    1984 SVO needs TLC

  8. #8
    FEP Super Member TWR2003's Avatar
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    Personally I think the MSD box would be a waste of your money. But its YOUR money. You can buy a brand new Motorcraft Duraspark module for $75. You will go thru 2 or 3 MSD boxes before that thing ever dies.

    To wire up a Duraspark system you only need two wires from the ignition switch - hot in START and hot in RUN:



    You will need a factory type resistance wire or a external ballast resistor.

    Be sure to get a Duraspark distributor with a STEEL gear. Theoretically you can buy a reman one with the correct gear or put the correct gear on one you have.

    I would recommend that you remove the EFI harness(s) and computer from the 87 and splice into the connectors at the underdash harness for the START and RUN wires. Id look for a good used Duraspark harness to minimize wiring.

    I do NOT recommend using the EFI high pressure pump on a carbd setup regardless of the regulator BS. You can also splice into the underdash harness/fuel pump relay for the fuel pump. You will need to make it a 'dumb' system in that the pump will run anytime the ignition switch is ON. Leave the inertia (crash) sensor in the system. I would also recommend an oil pressure safety switch.

    The stock tach in the 87 will work fine with your Duraspark system. Need to run a single wire from the neg (dist) side of the ignition coil to the proper connector/pin on the underdash harness that goes to the tach.
    Last edited by TWR2003; 05-16-2011 at 12:43 PM.
    MF: Shoot pool Fast Eddie.
    EF: Im shootin' pool Fats. When I miss you can shoot.

  9. #9
    FEP Power Member Syco Stang's Avatar
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    I've never ever had an MSD box die on me. Have they died on people? Sure! But so have the Duraspark boxes, so that's a redundant point. Why anyone would want to run a stock Duraspark, or why anyone would recommend it, in any sort of performance oriented setup/swap is beyond me. I am no parts pusher, but the MSD has multiple spark discharge, a rev limiter, and puts out a lot more power. Spend the money, don't buy a reman'd Duraspark box for $75 (or worse, jobber) and for the record a new old stock unit recently sold here for $110....... Buy an MSD.
    SS
    1986 GT T-Top 5.0, waiting on trans and IRS swap.
    1988 GT Ragtop, 5.0, T5, 3.73, 03 Cobras with Nittos
    1989 LX Ragtop, 5.0, AOD, shift kit, Pony wheels, baby cam, X pipe and Flowbasterds.
    1984 SVO needs TLC

  10. #10
    FEP Super Member TWR2003's Avatar
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    Quote Originally Posted by Syco Stang View Post
    I've never ever had an MSD box die on me. Have they died on people? Sure! But so have the Duraspark boxes, so that's a redundant point. Why anyone would want to run a stock Duraspark, or why anyone would recommend it, in any sort of performance oriented setup/swap is beyond me. I am no parts pusher, but the MSD has multiple spark discharge, a rev limiter, and puts out a lot more power. Spend the money, don't buy a reman'd Duraspark box for $75 (or worse, jobber) and for the record a new old stock unit recently sold here for $110....... Buy an MSD.
    SS
    What the hell are you talking about. Re-read my post!

    Who said anything about a 'reman' Duraspark box. They dont reman Duraspark ignition modules (boxes). I am talking about a BRAND NEW MOTORCRAFT DY893 Duraspark ignition module. $72.99 plus ship from Rockauto.com. And WHO says MSDs make 'more power'. Only MSD salesmen say that. You work for MSD? ADVERTISING HYPE. And MSDs crap out ALL the time. Ive got two dead units - a 6A and a 6AL. Ive NEVER had a MOTORCRAFT Duraspark unit die on me - ever. Maybe brand X Duraspark is crap but Im not talking about brand X.
    Last edited by TWR2003; 05-16-2011 at 07:53 PM.
    MF: Shoot pool Fast Eddie.
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  11. #11
    FEP Power Member Syco Stang's Avatar
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    Jesus Christ dude, relax. I never said they give you more power, they put out more power. I meant as in voltage. Fine, new Duraspark box at $72.99 vs a Jacobs, a Crane Hi6, an MSD..... I'd still pick the aftermarket unit.
    1986 GT T-Top 5.0, waiting on trans and IRS swap.
    1988 GT Ragtop, 5.0, T5, 3.73, 03 Cobras with Nittos
    1989 LX Ragtop, 5.0, AOD, shift kit, Pony wheels, baby cam, X pipe and Flowbasterds.
    1984 SVO needs TLC

  12. #12

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    Quote Originally Posted by Syco Stang View Post
    Why anyone would want to run a stock Duraspark, or why anyone would recommend it, in any sort of performance oriented setup/swap is beyond me. I am no parts pusher, but the MSD has multiple spark discharge, a rev limiter, and puts out a lot more power.
    It's a simple matter of whether or not you're solving a problem that doesn't exist. You're
    seriously underestimating the capability of the stock Duraspark system. And that's fine if
    you wanna spend the money. But for most of us here, the only thing a 6AL will get you is
    a rev limiter. "Hotter spark" is marketing BS, plain and simple. That's not a slam against
    the MSD ignition box, just the twits that write the ad copy, and the magazines that push
    that drivel on the rest of us.

    I really can't say whether DS or MSD are more or less reliable than the other, but I can say,
    there have been an awful lot of factory Duraspark modules that outlasted the car or truck
    they came with, and are ready for more if anyone cares to rescue them from the boneyard.

    And dude. Relax. It's just an ignition system, not yer manhood...
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  13. #13

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    WHOA!! Geez, sorry I asked. Ive been building cars, mostly 50 and 60's stuff since the 70's. This electronic crap is all new to me, that's why I want to go back to a carb and basic non-computor stuff for my '87. My 85 has no computor and it runs just fine. I decided to go with the duraspark set up because its no different then a pertronix etc and is cheaper and very reliable. I want to rip as much of the computer as I can out of the car so I can tune it and do what I want to it. My problem is, the computor itself. If I go carbed will that change, including removing all the sensors etc screw up the tfi distributor? I think it will, hence the need to change to the '85 5 speed distributor. As for the module, ford built the duraspark very well, its the cheap aftermarket modules that fail. Any help would be appreciated in helping me get this done right.

  14. #14
    FEP Super Member TWR2003's Avatar
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    If you are going to convert to the Duraspark ignition system you need the Duraspark distributor (with a STEEL gear for your application for a roller cam'd engine), the Duraspark ignition module (aka ignition 'box'), and all the interconnecting wiring. You can find a wiring harness or make your own - its entirely up to you.

    I dont see why you would still retain any part of the EEC system for a carbureted setup. The TFI distributor will only work with the EEC system. On the EEC system the computer controls or monitors/takes input from several ancillary systems (ie AC and crusie control) but you are deleteing the computer and these system will need to be set up as they are on a non-EEC (ie carb) application. You cant leave the computer with all of the inputs removed and expect it to control anything. Either all of the system or none. It should be quite straight forward - set it up pretty much like an carbd 85 5-speed.
    Last edited by TWR2003; 05-17-2011 at 07:16 PM.
    MF: Shoot pool Fast Eddie.
    EF: Im shootin' pool Fats. When I miss you can shoot.

  15. #15

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    Quote Originally Posted by Syco Stang View Post
    Sure! But so have the Duraspark boxes...
    You forgot the 200k miles and 25 years of service they usually put out before they die.

    -Mike

  16. #16

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    If i copied this correctly, this is the diagram I used. Bought my car with a tfi dizzy running a carbed 302. Dont know how they got it to work, but didn't work well. I am not an electrictian, and was intimitated to attemt the switch. I took my time and eliminated the comp harness. I then changed it to a mechanical fuel pump, the electric one in the tank wasn't getting the signal anymore. I actual used part of it to make the pickup in the tank. It is easier than it looks, I just went one step at a time and had no prob.
    Hope this helps. I used the dura spark box in mine. I did just hard wired it in because i didnt have theplugs on the cars harness. Good luck

  17. #17

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    It didnt copy, I was trying to copy TWR2003 diagram. that is the one I used. I found that switch from tfi to carb easier that this stupid computor stuff. Good luck..... again

  18. #18

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    Quote Originally Posted by kramerdad1 View Post
    hi guys. Im confused. the more I read the less Im certain about how to take a 1985 5.0 5 speed dura spark set up and install it into a 1987 GT cv that I am retrofitting to carbed. Can anyone tell me which wires in the TFI set up I connect to the distributor, the duraspark module and do I leave the box coil alone? Also, what wires do I splice, or re-wire to get the electric fuel pump to run? Im going to use a pressure regulator with a return line.

    I'm curious as to why you would remove efi for a carb? What's the point??

  19. #19

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    I'm old school. I want to be able to work on my car without a Phd in electronics and a room full of computors. I can fix my 65 mustang with a 1/2" wrench and a screwdriver, can't do that with a soleless computor. I read the steps needed to fix a loping idle with the computor controlled cars, all 12 pages of it, throttle sensors, this input, that output, phooey, I'm way too old to screw around with all this electrical crap, give me a set of points and a carb and Ill get home every time.

  20. #20

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    MEGA Necro on this thread If anyone reads this: TWR2003 is absolutely right in my opinion. Duraspark, for those who are savvy, is a go-to hotrod ignition because its cheap and effective. Go read the HAMB and you will see the Duraspark references. MSD 6AL has a place - I run one in a MOPAR because the OEM ignition harness has problems and MSD allows me to bypass the ballast, bulkhead harness and dreaded ammeter that's causing the problems. But the MSD units DO die. I shipped one off for repair a few months back which costs about $100 these days. Ironically, my MSD's sit cozy under the glove box in the interior so there is really no excuse for the failures. But fail they do so I have a spare box in the car at all times. Long story short, Duraspark just works and even if you have to build custom harnesses for the distributor to box its super simple. Find that red wire coming off the ignition switch and you are good to go. /NECRO
    65 Fastback 302/T5
    82 Mustang GT
    84 Mustang Predator GT302H 4S-119

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