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    Author Topic: Engine harness question  (Read 2192 times)

    Offline Husker Cuda

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    Engine harness question
    « on: May 05, 2015 - 02:38:14 PM »
    Hey guys, I installed a new M&H engine wiring harness for my 1970 GTX on Saturday. I know it's not an ebody but the wiring should be the same.  This is the one that is modified for electronic ignition. I removed the old harness which worked fine but had some questionalble wires & hacks on it. I then installed the new harness which looks wonderful. When I fired the car up it ran but it ran like the distributor was retarded a bunch, no power. The car was already setup for electronic ignition and had the ECU and the correct 2 connector field alternator. I added the new 4 pin ballast resistor and made sure I had the wires connected correctly on the ballast for the correct resistance. I got frustrated and put the old harness back on and it ran perfect once again. I ohmed out the new harness and it appears to be correct? Any ideas?  :2thumbs:
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    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed


    Offline Chryco Psycho

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    Re: Engine harness question
    « Reply #1 on: May 05, 2015 - 10:06:43 PM »
    dist pick up wires reversed maybe
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    Challenger - You`ll wish You Hadn`t

    Offline Husker Cuda

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    Re: Engine harness question
    « Reply #2 on: May 05, 2015 - 10:39:20 PM »
    Hey Chryco, I checked both harnesses and the positive and negative going to the distributor were the same. Not sure what else could cause this. I sent back the harness and the are sending me a new one so I'll see if the problem goes away with the new one.   Thanks. Good to hear from you again!
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    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed

    Offline Bullitt-

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    Re: Engine harness question
    « Reply #3 on: May 05, 2015 - 11:25:56 PM »
    continuity only tells part or the story, a poorly crimped terminal will not allow full voltage through. Check the voltage to the coil & ballast resistor with the old harness & see what you get with the new.
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!

    Offline Husker Cuda

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    Re: Engine harness question
    « Reply #4 on: May 06, 2015 - 09:48:46 AM »
    Good point Bullitt, I will check it out once my new harness arrives.  I did have a bad connection on the new harness on the wire that goes from the #2 pin on the ECU to the tach conn and back to the coil.  I had continuity from the #2 pin to the tach connector but nothing from the tach connector back to the negative side of the coil.  I made a jumper wire to go from this connector back to the coil to get it to run.  So if there is one bad connection, there could have been more.  The tech from M&H said these harnesses are usually bullet proof and had very few issues with them.  Leave it to me to get the one bad one!  Thanks Bullitt
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    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed

    Offline Blasterb

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    Re: Engine harness question
    « Reply #5 on: May 06, 2015 - 12:06:35 PM »
    I had some issues with my car wiring. Called M&H and they were very helpful. Have you tried asking them?
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    Offline moparman82

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    Re: Engine harness question
    « Reply #6 on: May 06, 2015 - 12:11:43 PM »
    Hey husker, you coming to the mopar show in papillion next weekend?
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    Scott in Omaha
    Searching for the right 70 Cuda driver
    1973 challenger in go-mango, on it's way to a 70 T/A clone SOLD
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    2019 Ram Laramie
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    24 mopars past and 2 present

    Offline Husker Cuda

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    Re: Engine harness question
    « Reply #7 on: May 06, 2015 - 01:11:58 PM »
    I'm sure going to try, never been but I will give it a shot.  Have to fire up the Cuda and head your direction!
    Logged
    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed

    Offline Husker Cuda

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    • Posts: 422
    Re: Engine harness question
    « Reply #8 on: May 06, 2015 - 01:15:49 PM »
    Quote from: moparman82 on May 06, 2015 - 12:11:43 PM
    Hey husker, you coming to the mopar show in papillion next weekend?

    Yes, I talked to I think Ken.  He was able to help me with where the negative coil wire came from but he had no idea what could cause the car to run right with the old harness but not the new one.  I'm hoping it was just a bad harness.  Should have a new one next week sometime.

    Mike
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    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed

    Offline Husker Cuda

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    • Posts: 422
    Re: Engine harness question
    « Reply #9 on: May 23, 2015 - 09:22:23 PM »
    Chryco was right once again!  I got my replacement harness and it ran the same with the engine running like the timing was retarded a bunch. I switched the two wires around in the dist and it runs perfectly. So someone must have switched them sometime in the past.  :cheers:
    Logged
    1974 'Cuda 512 stroker 650HP Indy heads, Hemi 4 speed, pistol grip - restored to new.
    1970 GTX 440/727 Y4 Gold w/ black interior
    1969 Camaro SS 396 4-speed X22
    1970 Chevelle SS 396 - 375HP M22 4 speed

    Offline Chryco Psycho

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    • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
    Re: Engine harness question
    « Reply #10 on: May 24, 2015 - 07:40:49 AM »
    Cool , I am glad it solved the issue  :2thumbs:
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    Challenger - You`ll wish You Hadn`t
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