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  1. #1

    Default 84 CFI to Carb Duraspark and Fuel Questions

    Hello,

    I swapped my 84 GT from CFI/Auto to Carb/t5. I have done a lot of research on the following questions but found too many conflicting answers. Hoping a few that have done the CFI conversion as well as Duraspark with an E Coil will chime in.

    I downloaded both wiring diagrams from AllData for an 83 5.0 Carb car and 84 5.0 CFI for references. I purchased a Duraspark American Autowire Harness, aftermarket blue grommet box, 85 distributor (for my 94 block), and have the factory 84 E Coil.

    My questions include:

    1. Ballast Resistor Wire - I understand the reason for this wire or adding in a ballast resistor block BUT my questions are - If I use the blue grommet module that is supplied with full 12v power (which is shown in my 83 diagram), why are others stating they are cutting down the power with a resistor? My diagrams only show the resistor in the coil circuit.

    2. My 84 CFI car had a E Coil that shows in the diagram to use full 12v power(No resistor is shown in the diagram). Instead of using the resistor and fluid filled coil, why not leave the wiring alone and still use the factory 84 E Coil. This would leave the factory wiring in tact and have a better coil. How can this effect the module if it is on a different circuit? The only wire going from the module to coil is on the ground side.

    3. If I disconnect the high pressure frame pump, will the factory in tank lift pump have enough pressure to the carb? I have seen some say it works fine and holds pressure, others stated it is only a lift pump and will not work. If the answer is yes, will the high pressure pump allow fuel to pass if I disconnect power or does the actual fuel line need to be bypassed as well.


    I know this is a lot and appreciate any assistance in advance.

  2. #2
    FEP Super Member xctasy's Avatar
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    Follow EXPOfoo85LTD_LX's two posts #19 & #20.

    quickshift, never and WalkinTall covered the rest.

    http://vb.foureyedpride.com/showthre...arb-conversion


    On page 5 of WalkinTalls 86 Convertable CFi to Carb conversion you get some of the best info on using the primary lift pump.

  3. #3

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    Quote Originally Posted by xctasy View Post
    Follow EXPOfoo85LTD_LX's two posts #19 & #20.

    quickshift, never and WalkinTall covered the rest.

    http://vb.foureyedpride.com/showthre...arb-conversion


    On page 5 of WalkinTalls 86 Convertable CFi to Carb conversion you get some of the best info on using the primary lift pump.

    Thanks. I guess the only questions I still have is if there is a reason to not use the stock 84 E coil with a duraspark distributor/box and if that is ok, why a resistor would be needed?

  4. #4

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    Quote Originally Posted by moddedstang View Post



    3. If I disconnect the high pressure frame pump, will the factory in tank lift pump have enough pressure to the carb? I have seen some say it works fine and holds pressure, others stated it is only a lift pump and will not work. If the answer is yes, will the high pressure pump allow fuel to pass if I disconnect power or does the actual fuel line need to be bypassed as well.


    I know this is a lot and appreciate any assistance in advance.
    I heard this as well and tried it prior to running both pumps. It did NOT work as said. Later I found out why. There is a resistance wire feeding the in tank pump to lower the output and be used as a lift pump for the frame rail pump. This will only produce about 2-3 lbs pressure. Apparently, if you replace this wire, you will get about 6lbs. Never tried it. Like the return system I have better.
    84 Cougar, 90 HO with 700DP, Edelbrock RPM intake, 1.7 RRs, shorty's and SS exh, T-5, KC clutch, Hurst pro billet, line loc, 8.8, 4.10s, suspension mods....blah, blah,blah.

    71 Comet, 289, Liberty TL, 9", 6.00s, 11.9x @ 112.... blah, blah, blah.

  5. #5

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    The resistor is used when the module is in the run position as to not overheat the system unnecessarily. Without the resistor, there is full voltage to the coil in the start position to ensure better starting......supposedly.


    84 Cougar, 90 HO with 700DP, Edelbrock RPM intake, 1.7 RRs, shorty's and SS exh, T-5, KC clutch, Hurst pro billet, line loc, 8.8, 4.10s, suspension mods....blah, blah,blah.

    71 Comet, 289, Liberty TL, 9", 6.00s, 11.9x @ 112.... blah, blah, blah.

  6. #6

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    Different perspective and YES you can use the E coil.


    NOTE: These colours DO NOT necessarily relate to what you have or are doing. I posted this for illustration purposes only!
    Last edited by quickshift; 10-26-2019 at 07:05 PM.
    84 Cougar, 90 HO with 700DP, Edelbrock RPM intake, 1.7 RRs, shorty's and SS exh, T-5, KC clutch, Hurst pro billet, line loc, 8.8, 4.10s, suspension mods....blah, blah,blah.

    71 Comet, 289, Liberty TL, 9", 6.00s, 11.9x @ 112.... blah, blah, blah.

  7. #7

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    Quote Originally Posted by quickshift View Post
    I heard this as well and tried it prior to running both pumps. It did NOT work as said. Later I found out why. There is a resistance wire feeding the in tank pump to lower the output and be used as a lift pump for the frame rail pump. This will only produce about 2-3 lbs pressure. Apparently, if you replace this wire, you will get about 6lbs. Never tried it. Like the return system I have better.

    I didn't notice the resistance wire to the pumps until you sent this. Then I looked at my print out and bam there it is. I appreciate the heads up. I may just wire in a new pump. Name:  1984CFI-FUEL.png
Views: 119
Size:  75.7 KB

  8. #8

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    Quote Originally Posted by quickshift View Post
    Different perspective and YES you can use the E coil.


    NOTE: These colours DO NOT necessarily relate to what you have or are doing. I posted this for illustration purposes only!
    I have always been weak with electrical circuits. I appreciate you clearing up that I can use the E coil and I understand why the use of the resistor in certain applications but what I am trying to understand is if the 84 has managed to run without it for all these years, why does it need to be added now by adding duraspark? Unless, the 84 does indeed have the resistance wire and it doesn't show on diagram below OR the E coil doesn't need it.

    I may just add it so I don't have to worry about it but the reason for these questions is to not add an ugly part that may or may not be needed for a coil that seems to be already running on 12v for the CFI.

    Thanks again everyone.Name:  1984CFI-IGNITION.png
Views: 121
Size:  123.1 KB

  9. #9

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    That resistor is to be used when you convert to the Duraspark from the TFI. I run a resistor with my setup and have no issues. It could be that my coil puts out 65,000 volts. I did this back in 04 so my brain is a little foggy.
    84 Cougar, 90 HO with 700DP, Edelbrock RPM intake, 1.7 RRs, shorty's and SS exh, T-5, KC clutch, Hurst pro billet, line loc, 8.8, 4.10s, suspension mods....blah, blah,blah.

    71 Comet, 289, Liberty TL, 9", 6.00s, 11.9x @ 112.... blah, blah, blah.

  10. #10

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    Quote Originally Posted by quickshift View Post
    That resistor is to be used when you convert to the Duraspark from the TFI. I run a resistor with my setup and have no issues. It could be that my coil puts out 65,000 volts. I did this back in 04 so my brain is a little foggy.
    After looking at my ignition wiring diagram, instead of adding in the ballast resistor, what about disconnecting the run wire and running a new ballast resistor wire such as the Standard Motor Products RW34 which is rated at 1.35 ohms. If I did this, I would could cut the old run (red/light green) wire a few inches from the fusible link and splice it in, should work as factory when turning ignition. Thoughts?Name:  1984CFI-IGNITION.png
Views: 100
Size:  123.1 KB

  11. #11

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    " Thoughts? "

    .....stick with what works.

    Why? You posted this in post #8......."I have always been weak with electrical circuits."
    84 Cougar, 90 HO with 700DP, Edelbrock RPM intake, 1.7 RRs, shorty's and SS exh, T-5, KC clutch, Hurst pro billet, line loc, 8.8, 4.10s, suspension mods....blah, blah,blah.

    71 Comet, 289, Liberty TL, 9", 6.00s, 11.9x @ 112.... blah, blah, blah.

  12. #12
    FEP Senior Member
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    The Duraspark module will apply full 12 volts to a stock oil coil when cranking, then it will drop to @ 9 volts when running. If you use an E coil, it will only get @ 9 volts during run mode from the Duraspark. You can wire the E coil to a keyed 12 volt source and not use the coil wire from the Duraspark. You can also get an oil coil with or without an internal resistor.

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