70 Challenger RT - EFI 6 Pack Conversion

[70chall440]

Finally got back to work on the car, had to remove all of the temp wiring and am now in the process of routing and mounting everything. I was able to get the ECU mounted which is nice... 

I purchased a SA book on EFI conversions and hit upon a section on the charging system, the author seems to think/believe that you should have a 100amp or better alternator which I do not. So, I am not looking at the entire charging system; yes I still have the dreaded amp gauge and for the time being I am keeping it. That said, I am looking at my overall options.

[70chall440]

For anyone considering this conversion or one like it, I have discovered that the charging and general wiring system needs to be upgraded. Evidentially the factory 60A will not cut it, therefore I spent the day researching a new alternator and associated components. What I settled on was the following

1. 120 Amp Alternator from O'Reillys; 91 Dakota NippoDenso w/dual V groove pulley = $100
2. 4 gauge wire (run from the alternator to the starter relay to relieve the strain on the amp gauge)
3. various fuse/distribution blocks to feed the "switched" requirement of the ECU, MSD6AL and Tach adapter

Now I am in the process of trying to fit, align and install all of the above. Still need a 100 Amp ANL fuse for the alternator feed wire.

[crash340]

I have a Tuff Stuff 100A alternator to fit to mine so hope it's big enough, I don't have electric fans, stereo, AC, spot lights or anything other than the basics so it 'should' be ok, Mike, can you document the install of your Denso alternator please including the wiring

[crash340]

I'm guessing the Denso alternator will charge better at idle as well?

[70chall440]

After a lot of reading I determined that I needed at least 100A and like you I do not have electric fans or a big stereo, etc. I chose this alternator for several reasons;

- first is that I can get it locally at any parts store
- it is relatively inexpensive ($96.00)
- it comes with a V groove pulley
- it is relatively small in size
- has a limited life time warranty
- accepts an external regulator (comes with a sticker saying "alternator is regulated by the ECU" because in 87 and up Dodge trucks, some had the regulator in the ECU, however you can use a normal Mopar Electronic regulator with it)
- it will definitely charge better at idle

This is the same alternator that I am using on my Cuda so from a physical size standpoint I was confident it would work. The other thing is that it does not look like a GM alternator (small issue but IMO one worth mentioning).

This alternator has essentially 2 mounting points; on one end there are 2 castings between which you would expect a spacer (in its original mount there is a mounting plate with a "ear" which fits between these castings). On the other end is just a single casting with a hole (this would be where the adjustment would normally be). In my application, I intend to use the single casting as the top hinge point and the forward ear of the dual casting as the adjustment lock point. The reason is that this puts the wiring terminals on the top where you can see and get to them. As I work this this, I may change my mind but we will see. I intend to make some weather pack disconnects for the field wires and perhaps something for the 10 gauge wire I have going there from my lights so that I can easily connect and disconnect everything.

I will document what I am doing.

[crash340]

Thanks Mike, so provided one purchases one of that model alternator, it's basically a drop in replacement from an electrical connection point of view right?
What is the part number please

[70chall440]

From an electrical standpoint, yes it is a direct replacement. The details are;

Brand - Ultima
PN - R110666A
Application - 1990 Dakota 5.2 w/AC
Amperage - 120

[ShelbyDogg]

From an electrical standpoint, yes it is a direct replacement. The details are;

Brand - Ultima
PN - R110666A
Application - 1990 Dakota 5.2 w/AC
Amperage - 120

I'm pretty sure the charge lug hits the head on a dual belt AC big block.

[70chall440]

I mocked it up last night and it didn't, in fact I think I need to space it out (towards the radiator) about 1/16 or so for good alignment which gives me even more space. I will get a picture and post it here later.

[74BlueFish]

I'm using the powermaster  #79091 from Bouchillon Performance.  sticker says 75/66 amp   (75/50 amp   at speed and idle)   The testing slip says 66 amps at 2400 rpm and 95 amps at 7500 rpm  (alt rpm  not the engine)

I know this isn't as powerful as what you are looking at but,

Seems to be working fine, never shows a discharge.  Stereo with amp and woofer, A/C,  Headlights on relays, Megasquirt fuel and ignition.

But, I would put the biggest I could find that fit if I had to it over again.

Dan

[70chall440]

Today I began the installation of the new alternator. To the previous point, the charging wire stud will not hit the head if you mount it with the twin prongs of the new alternator on the bottom. After looking it all over, I knew I could make it work using the factory mounts, however since I despise the "pull and tighten" method of belt tensioning, I decided to make new mounts and incorporate an adjustment rod.

Still very much a work in progress, however this is the beauty of retirement... Here are some pictures. I am going to be using a Littelfuse Mega fuse system and will be running a 120A fuse.

[70chall440]

Greg - here is the wiring diagram I intend on using.

[74BlueFish]

Very nice fab work there.

[70chall440]

thanks, it took awhile but I am happy with the results. Still have the upper end to do (hopefully today) for the rod end adjustment rod (tensioning rod).

[crash340]

Nice bracket Mike