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1981 5.7 Hemi RC Complete

15K views 14 replies 9 participants last post by  Clem 
#1 ·
Just finished installing a 2007 fuel injected 5.7 hemi into my 1981 RC.  She runs awesome now with the fresh power and fuel injection.  I haven't gotten a whole lot of highway time on her yet because of winter, but the miles I have on it so far showed me just how fast that speedo climbs now.  Especially when you get the motor wound up a bit, that speedo just shoots up from 40 to 65.  The swap did take time to do and a list of parts, but not impossible or even that hard.  I chose to do this swap because rebuilding an old 360, and putting an injection system on it would have cost about the same price as dropping in the hemi.  Feel free to ask any questions about this swap.     
 
#2 ·
Nice! How'd you handle the wiring? Use OEM stuff and a modified factory harness?
 
#4 ·
Garonimus said:
Does your Hemi have MDS? I'd be interested in seeing if your mileage improves significantly with it.
X2
 
#5 ·
Did you use the 07' tranny and transfer case? I would imagine that you could swap the entire drive train with the harness with out too much trouble other than the mounts. Did you keep the obd 2 connector? It would be kinda cool to identify the rc as an 07 ram. Also you could run programmers they make for that truck. Cool swap cant wait to here details and see some pics!
 
#7 ·
#8 ·
Yeah we're all sitting here waiting for the DETAILS!!!
This is next on my list... 
Build thread?
Josh
 
#10 ·
Sorry for the delay, my internet has been on the blink lately. 

First off I ordererd a new wiring harness, I didn't use the stock one.  I used an 05 computer and had it programed.  the harness was an easy install.  It comes with everything your need, just have to wire in a few wires, ignition, hot, ground,  run switch wire, and your set.  The harness does come with the obll port, so you can hook up an aftermarket programmer or diag tool.  All I had to do was alter the position where ithe harness entered the firewall because of the heater box.  It looks so much better then all those ignitions boxes that were screwed to the firewall/fender.  Really cleaned up the engine bay.  You can run the dialbo programmer to tune it more if you want, like for a cam and such.  I will most likely do this at a later date after I get some more base line tests done on performance.

I use a 518 tranny with the standard 241 t case.  Bolts right up using a spacer plate from S&P.  I also had to use a mini starter that can be sound on the 90's dodge motors.  The old big bertha starter is too big to fit.

Engine mounts were ordered from S&P also.

The MDS will be disabled with the "Hotrod" harness/program.

Like I mentioned I used the stock fuel injection which works great.  Installed an in tank pump and ran new lines.  Pretty straight forward.  You can also put an aftermarket FI system on it from FAST or Eldelbrock.  Additionally you could run a carb system on it too. 

Pictures to come.  Sorry no mpg yet, Im waiting for winter to pass.  I will get them posted as soon as I get some good highway miles.

Keep shooting questions, I will get to them as quick as I can. 



 
#11 ·
The way you did it is as cheap as it gets for best results. There's not really much inherently "wrong" with the stock injection for the most part. The wiring harness and overdrive are the biggest deviations you made from cheap. You could use a 727, but since this motor has more headflow and will have the power higher up than a mild 350hp SB, the OD and steeper gears will help it a lot.

I'm not aware of a good t-case with the proper drop that the (5)45RFE gets along with well, and the trans is expensive to fix, also has to run on a computer itself, where most of that trans' issues lie. For whatever reason after '93 they started using a lot more t-cases and trannys that shouldn't be in a full size. Honestly, I'm not a fan on that trans at all. At best it's sketchy. Since 4.7s and 5.7s use the SB bolt pattern, can't see much reason to run anything other than a good hydraulic 727/518.



 
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