1971 Charger Gen 3 Hemi Swap/Build Plan

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  1. RockyPat

    RockyPat Well-Known Member

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    Hello everyone,

    I would like to start by saying that I am new to the muscle car world and not very mechanically sound. I am young and would like to learn! I would not mind taking a lot of time to finish this project. I am trying to be sensible with the money I spend on the car. I am trying to be frugal with the understanding that spending more for a better setup can be worth it.

    I plan to keep the patina of the car and make it a ratty, mechanically sound build with either some steel wheels with hub cabs or 17 inch magnums.

    I recently purchased a 1971 Charger with a 318/904, front bench seat, and other base model attributes.

    I will most likely need to rebuild the 318 and 904 unfortunately. While I was adding up the costs of rebuilding both items, a thought popped up into my head: Why not a G3 Hemi swap?

    I know it is a lot of work and there are many parts modifications that need to be purchased and addressed.

    I also do realize that it would cost more to do the hemi swap than rebuilding the 318/904 combo. BUT, would it cost way more to a point where the swap is not worth it?

    A 5.7, 6.1, or 6.4 hemi with an overdrive automatic transmission or a 5/6 speed with fuel injection would be more fun, reliable, and powerful.

    I am in the process of taking off the grill, front clip, fenders, and hood to fix some frame damage. I have also taken out the carpet and have no interior left in the car besides the dash (if I needed to cut the transmission tunnel there would be nothing in the way).

    My original bench seats are all torn up and would need to be redone, and the non-R/T instrument cluster is broken and needs to be replaced. Meaning that I would need to replace most of these parts regardless of the type of engine, so I could cater replacement parts to work the hemi swap.

    I really like some of the seats in the newer Charger/Challenger RTs SRTs.

    My thinking is to try to buy a wrecked car on Copart with a low mileage hemi and transmission and nice seats to use in my 71 since original bucket seats are EXPENSIVE. GOOD/BAD idea??

    Then, I would have a complete donor car to work with and I could potentially sell unneeded parts to recoup some of my costs.

    Has anyone done anything similar to my plan?

    Anyone see any problems with my ideas?

    Should I just stick with the 318/904? Any other engine upgrade would cost a lot of money besides a 360 probably, so I am either thinking G3 hemi or the original 318.

    Here are pictures of my 71 Charger:

    IMG_5828 (2).JPG IMG_5834 (2).JPG

    Some potential seats I would like to put in my car (2009 Charger RT) (also, I would like to use the back seats if possible):
    Charger RT SEATS.jpg
     
  2. Purepony

    Purepony Well-Known Member

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    I have those seats in my challenger and they work for me

    I used the rear original seat off the challenger (1970) and had the seat cover removed from the newer one to fit and looks good
    I’ll post pics

    I also saw this
    Maybe it ll give you some ideas 3AA84186-F28C-429D-90AF-D641CA14C5AF.jpeg
     
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    • mschoo92

      mschoo92 Well-Known Member

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      When you say you aren’t very mechanically inclined, do you mean you haven’t done anything on this level (engine swap), or are you a newbie to automotive work altogether? Nothing wrong with either case at all, but it may affect which is the better route for now.

      An engine/trans swap is a pretty big project, you may be better off keeping the car as-is for now and learning with the current configuration - once you gain confidence, learn the car inside and out etc a cool “stage 2” for your build would be the swap.

      that’s my recommendation, unless you have friends/family who are mechanically inclined and willing and able to help! Whichever route you go, best of luck and be sure to ask questions & share your progress along the way! :thumbsup:
       
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      • Polara426

        Polara426 Well-Known Member

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        I am building a 71 Charger Gen 3 now. I would first decide what drive train and whose controller you would use. Then decide if you are keeping the torsion bars or converting to a coil over or some other suspension. Keeping the 318 would be your least costly choice. A 5.7 and A518 or 727 would be the next level keeping the torsion bars. There seems to be more stuff available for this every day. Good luck.
         
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        • Purepony

          Purepony Well-Known Member

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          At least a 518 seems kind of pointless to gain fuel injection on a whooping three speed automatic
           
        • 70chall440

          70chall440 Well-Known Member

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          Your plan is a good one (buying a donor), I've done it many times. So long as you have the space to be able to store, disassemble, etc. the donor you are good. If you look, G3 hemi powered vehicles are cheap, a buddy just bought a Chrysler 300 with a 5.7 for $2500.

          What concerns me is this, you admitted that you don't have much if any experience and are not overly mechanically inclined. Putting a G3 hemi with a modern AT into the 71 is not rocket science but it does require some skill as you will have to clearance the trans tunnel, do some significant wiring (in fact I would probably replace the entire harness). There are quite a few moving parts in this effort and as essentially a "first project" it is a bit much.

          I am not trying to discourage you but this has all the makings of so many similar projects that were started with good intentions and somewhat of a plan only to be abandoned because the owner got in way over his head. It definitely can be done, but it is going to be a pretty steep learning curve.

          My recommendation to you is to stick with the 318 and 904 for now, try and get that engine running decent in its present condition. I would not completely disassemble the car are you are doing, I know all the tv shows do that but you are asking for some pain in lost parts and things not going back together. Get the car cleaned up and running if possible and then start small; get the interior sorted out (you can do a simple cover for the seat or replace the seats as you mentioned). You need to keep the car somewhat viable/running until you are absolutely ready (and able) to pull the drive train and repair/replace it. By keeping it relatively together and if possible running you will stay excited about it, disassembling it and then trying to figure out how to get it back together is probably not going to end well.
           
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          • SSmoothie

            SSmoothie Well-Known Member

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            Cost wise you are looking at triple or quadruple the if you do a Hemi swap. Depending if you purchase an engine new or used. Aftermarket wiring harness alone is 3k. You will need to make sure the front suspension can hold the weight of which engine you use. Research other sites and ask a lot of questions.
             
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            • 70chall440

              70chall440 Well-Known Member

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              I disagree with those who say the hemi swap is tremendously more expensive than rebuilding what you have, it all depends on what you have what you can get a hemi/trans for. If you get a donor car for sub $5K that is in decent condition you get the engine and trans. I would not use the donor ECU because it needs to get reflashed and you can't do much with it. I would opt for a Holley Terminator X system ($1700) that can be tuned with a lap top.

              I am not saying it is cheaper to do the Hemi swap but it just depends on what you have now, what you can get a donor for and what your goals are. You can spend a lot of money rebuilding a stock LA engine (318/340/360 etc.) but if the engine isn't real bad you could perhaps just get away with new bearings/rings and a hone.

              You probably don't need an entire new wiring harness but you will most likely need to repair what you have and probably modify it to take more power if you are going to upgrade the alternator.
               
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              • nstyle73

                nstyle73 Well-Known Member

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                I agree that the Gen III swap is much simpler these days but it is still not just drop in and go. Holley has come through for controlling the engine and the Nag1 and there is a stand alone controller for the 8spd now as well. However, there are still electrical interface issues with the stock wiring to figure out, pinion angle/drivetrain angle and accessory details among other things that will take up hours and hours or $$$ I’m a huge supporter of this swap, I bought a running, driving donor vehicle for $4500 with a 6.1 based 426, by all means don’t take this as discouragement. That 600 ish hp that fires up immediately and never sputters or misses is awesome, but like many, I haven’t actually gotten it into the vehicle yet. If your timeframe and workspace/storage area allows, I say go that route and learn along the way.

                Also, the Charger back seat will fit right in, you will have to make a way to fasten it in, the front seats, like mentioned previously, will be too tall to work right. There are other modern options that work well though
                 
                Last edited: Jul 14, 2021
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                • 451Mopar

                  451Mopar Well-Known Member

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                  • Polara426

                    Polara426 Well-Known Member

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                    A518 has overdrive once your in high gear what's the difference he asked for inexpensive options. 8 speed takes major floor and crossmember work and is very expensive. Some of the fastest drag cars have poweglides.
                     
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                    • nstyle73

                      nstyle73 Well-Known Member

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                      Nag1 are an easier alternative but 8hp70 are $500-$750 from parts wholesalers, not including a controller but yes they do require floor cutting, which he said he was comfortable with and a prefab tunnel reinforcement and crossmember are now available.
                       
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                      • 451Mopar

                        451Mopar Well-Known Member

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                        I haven't seen a 8HP70, but the NAG1 is not a huge transmission.
                        Not a big deal if you don't mind modifying the floor and crossmember, but I don't think it is a bolt-in type swap with the overdrive transmissions.
                        I have a 6.1L with Nag1 for a swap. Bought a factory type shifter, and throttle pedal (drive by wire). Have too many other projects before getting to the '69 Coronet Hardtop
                         
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                        • RockyPat

                          RockyPat Well-Known Member

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                          Hello everyone. Thanks for all of the input.

                          After some careful consideration, I think I am going to try to find an inexpensive 440/727 to swap into my car because it will probably end up being cheaper and easier to do.

                          From what I have read, a 440 can make some really good performance numbers, and I think it would be an easier platform to learn on than a modern engine/trans that was never meant to go into my car.

                          If I was better mechanically, then I might consider the HEMI swap.

                          Maybe on another project down the line if I can ever afford another!
                           
                        • 70-74 Cuda

                          70-74 Cuda Well-Known Member

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                          Gen 3 hemi swap are pretty easy to do. The wiring is not hard to do if you got the wiring diagram. It would be cheaper to get ur original engine running tho.
                           
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                          • 70chall440

                            70chall440 Well-Known Member

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                            Modern hemi is basically "plug and play" when it comes to the wiring side. Its no more difficult (and perhaps even less so) than a conventional engine assuming you are using a reputable harness. That said wiring a conventional engine isn't very hard either but its the rest of the wiring that gets most people.
                             
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                            • 70-74 Cuda

                              70-74 Cuda Well-Known Member

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                              I made a video showing where every wire goes and how to wire it to you're car.
                               
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                              • Purepony

                                Purepony Well-Known Member

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                                Hi where’s this video ?
                                 
                              • 70-74 Cuda

                                70-74 Cuda Well-Known Member

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                                • 70chall440

                                  70chall440 Well-Known Member

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                                  Good video, there is a lot going on there. Congrats on getting the car running.
                                   
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