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Discussion Starter · #1 ·
I'm in the final stages of my EFI swap and need to figure out the wiring of the Rally Pac. The RJM harness has a tach out wire but it is for common voltage triggered tachs that connect to the negative side of the coil. Stock, the Rally Pac tach, including the repop one I have, is wired in series with the hot lead to the coil.

I'm guessing that I can just wire in the tach to in-line with the hot lead to the tach for the EFI swap and I should be good to go. Has anybody done this or know of any reason why it won't work?

Thanks,
Jeff
 

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Discussion Starter · #2 ·
I guess I'll be the pioneer with this swap. :eek: I'll let you guys know if it works so somebody using the search function in the future will either be able to wire theirs properly ... or avoid frying it. :shocked:
 

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Discussion Starter · #4 ·
Yeah, I just pulled the MSD and tach adaptor and am going with the EEC-IV system alone without the MSD.
 

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gothand said:
Yeah, I just pulled the MSD and tach adaptor and am going with the EEC-IV system alone without the MSD.
But you still need a tach adapter as the vintage tachs look for a different type of signal than a 5.0L tach. MSD has the adapters.
 

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gotstang said:
gothand said:
Yeah, I just pulled the MSD and tach adaptor and am going with the EEC-IV system alone without the MSD.
But you still need a tach adapter as the vintage tachs look for a different type of signal than a 5.0L tach. MSD has the adapters.
Well now you have me curious. Will the regular MSD tach adaptor work?

Phil
 

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Discussion Starter · #7 ·
Just to update this thread for the archives and those considering a Rally Pac with the EFI, it works like a charm by wiring it in series with the hot lead to the coil. This will work for a current triggered tach like the original RP or the Oval Industries repop units. I believe the Scott Drake tach is wired by connecting to the negative side of the coil. In this case, you would just wire it to the tach output from the EFI ECU.

Jeff
 

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Since you recently used the RJM harness (me too), what did you do with the single green wire ALT run lead?

Dave
 

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I have the MassFlo kit, it uses the RJM harness. The green wire labeled ALT is tied up under my dash, never had a problem charging or with the EFI. I used the original charging system for one year and last year switched to a one wire Powermaster unit.
 

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Discussion Starter · #10 ·
I'm not using the alternator connection either. Prior to the swap, I already had the serpentine setup on this car and an internally regulated distributor. My 'activating wire' for the alternator runs through the 'ALT' light like the original.

Jeff
 

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I am using the RMJ harness and used the G2 alternator first. When I converted to a G3 alternator the alternator harness I purchased from RMJ had a plug that plugs into the main EFI harness. I don't think you need the connector if you have a G2 alternator. Leaving it disconneted did not seem to matter for me.
 

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Well now I'm glad I asked...

I'm using this Ron Morris ALT harness.

Ron Morris 2G ALT harness

The "eyelet" terminal hooks up to the battery/starter solenoid. The other (green wire) connection states that it is required to "turn on" the ALT. The Ron Morris instructions are very weak. The instructions state to "hook up the harness to the factory connections".

The RJM harness instructions state that the lone Green wire should attach to the ALT....

If you guys are saying that you left these wires disconnected on both ends and are having no problems, I need to disconnect/seperate these two wires....

Thanks,
Dave
 

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Dave,

I used the exact same Ron Morris harness when I had the G2 alternator. I had to do the conversion to G3 after I purchased a polished g2 alternator that had a slightly different connector on the alternator. I took apart the donor car alternator and swapped over the connector to the polished one. I must have done something wrong because when I hooked up the battery the wiring started to smoke and I fried the Ron Morris harness. :shocked: At least the car didn't catch fire. The wires were welded together and the insulation burned off in about 2 seconds.

I then read about some fire issues with the G2 alternators and decided to go with G3. I have a stereo with 2 amps so the extra juice a G3 puts out was needed. If you plan on running a lot of accessories and stereo like me you may want to consider the upgrade at this time.

I have to give you the disclaimer that I never ran the engine for extended periods of time so I don't know if it actually charged the system. The gauge read normal though. I suggest if you run into charging problems hook up the wire at that time.

Darreld
 
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