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Another 5.7 swap Question

Dreamcatcher

Dreamcatcher

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Ok, I have read about all the Hemi swap threads I can find (here and else where) I haven't seen an answer to my question. I too am about to install a 5.7 in my 68 Charger. And for the puritans here it is a 68 base Charger that at one time was a 6 Cylinder car that was changed into a 440 car. (Weren't they all changed into a 440) I bought a rolled 03 Hemi 2WD truck complete. I wanted to use the auto overdrive transmission. But I do not want to cut the new 500.00 AMD floor pan I just installed. I understand I can use the 727 and keep things engine back stock. Question 1. What mileage can I expect using the EFI and my older transmission? Question 2. I understand this truck had two computers, will the engine work with just the engine computer? I want to use the stock truck computer and sensors. Thank you for any and all help.
 
Dreamcatcher said:
Ok, I have read about all the Hemi swap threads I can find (here and else where) I haven't seen an answer to my question. I too am about to install a 5.7 in my 68 Charger. And for the puritans here it is a 68 base Charger that at one time was a 6 Cylinder car that was changed into a 440 car. (Weren't they all changed into a 440) I bought a rolled 03 Hemi 2WD truck complete. I wanted to use the auto overdrive transmission. But I do not want to cut the new 500.00 AMD floor pan I just installed. I understand I can use the 727 and keep things engine back stock. Question 1. What mileage can I expect using the EFI and my older transmission? Question 2. I understand this truck had two computers, will the engine work with just the engine computer? I want to use the stock truck computer and sensors. Thank you for any and all help.
Click to expand...

Well I can't tell you milage with a 727 but with a 5 speed manual with od in my coronet I ger 21 mpg.

You need to send the computer to hotwire auto and have the ma ual trans tune put in the computer if you want to run the 727. That second computer is a transmission controller.

Also the 03 computers and wiring only uses one oxygen sensor. If you plan to run dual exhaust you will have problems with running very rich and poor fuel economy unless you y pipe the exhaust into one pipe past the sensor....or run an 04-08 computer...preferably 05.

If you want to keep an auto bite the bullet and cut the floor....its worth having the 5 speed auto...
 
Gotta ditch the 03 computer. it cannot be tuned. Easy swap is a 6 speed, but as you said the floor must be cut.
 
According to what I have read the '05 manual trans computer is the only one that works in a classic chassis swap. I'm not saying that the others won't work, but the 05 is the simplest of the factory systems to use. The best thing you could do is call Dave Weber at modern muscle (site sponsor) and hear what he has to say about your particular needs. Or mega squirt makes a $1300 ECM with harness that several folks have been using successfully.

On the trans, I would seriously consider bolting on a gear vendors overdrive unit. No floor mods required but you will have to shorten the drive shaft.

I know of a 71 sat with a cammed 5.7, 727, and 3.55 that gets 14-15 mpg. But he drives it very conservatively most of the time. As far as I k ow, all other auto overdrive trans options require trans tunnel and crossmember mods.

Hope this helps.
 
If I have to cut the floor I just as well use this auto in the truck and use both computers. If I transfer everything over it should work right? I have done a mustang cobra into a 79 truck and a TPI into a 71 chevelle and never had issues. The only issue I see is I might have to use the cluster in the car as well. I have the entire truck. As for the single O2 sensor , how about running an x pipe and putting the sensor in the center?
 
Don't use the 03' computers!!!! No tuning availability compared to the 05' computer.
 
probably just ditch the whole project. Hardly seems worth the trouble for that kind of mileage to me. I have a 440 hp that is in my RR that will do 12 to 13 MPG. I was after better mileage. When we did the 350 TPI in the Chevelle it gets 20+ MPG.
 
Why not put a Gear Vendors od on the 440/727 combo and and get 17-20 mpg? I mean, if you're just looking for better mileage, to me, that seems like the simplest solution. That's what we're Fixin' to do on dads 67 383 charger. I've thought it out and a GV OD is just the best option with the fewest potential problems and lowest cost for us. We considered a 5.7 swap and decided we'd be thousands ahead with the 383 and GV.

Now my 69 coronet is a different story. I'm going 5.7 Eagle because that's just what I want to do. Period.

Did the Chevelle have an OD trans? I'm thinking it did. even a cammed and modified 5.7 can get 20 with an od trans.
 
The Chevelle is old school 4 speed with 391 gears and 18 inch rubber. The Tuned Port Injection motor is out of an IROC Camaro. I am not a lover of GM I did this car for my wife. But it runs good and gets very good mileage. Was in high hopes the Charger would be close. I have several big block cars Mopar and Ford as well and well lets face it their days are numbered as for drivability. More alcohol added to the fuel and that isn't good on them. Plus they just don't get any mileage with it. I have a 300C that is a big heavy car and with its 5.7 Hemi I get around 22 to 23. So figured the charger might be close.
 
Another question would then be has anyone cut the transmission hump and still been able to use their console and have it look right? Even if I did go through with the project I wouldn't want to loose the look of the interior of the car as it is a big part of how cool these chargers were.
 
Dreamcatcher said:
probably just ditch the whole project. Hardly seems worth the trouble for that kind of mileage to me. I have a 440 hp that is in my RR that will do 12 to 13 MPG. I was after better mileage. When we did the 350 TPI in the Chevelle it gets 20+ MPG.
Click to expand...

If you stick with an OD trans or keep the engine speed down you will get 20+ mpg. I have heard of 6.1's getting 23-25 mpg hwy. I have been consistent with 21 and think that could be improved if I change rear end ratio's from 2.94 to 3.23. I actually need it to spin a little faster at 60 mph.

I would probably ditch the 03 computer and harness setup unless you want to run that transmission though..

There is one benefit with the 03 harness in that you can remove one wire and remove the torque management for firmer shifts and better throttle response without a tuner...

- - - Updated - - -

Dreamcatcher said:
If I have to cut the floor I just as well use this auto in the truck and use both computers. If I transfer everything over it should work right? I have done a mustang cobra into a 79 truck and a TPI into a 71 chevelle and never had issues. The only issue I see is I might have to use the cluster in the car as well. I have the entire truck. As for the single O2 sensor , how about running an x pipe and putting the sensor in the center?
Click to expand...

The x-pipe would actually make it worse...you need it to see all of the exhaust flow from both banks to get an accurate fuel mixture reading or it will keep adding fuel. If you run a hotwire system I'd say find an 05 computer...doesn't need to be a manual trans truck either...it can be an auto..you just don't use one of the connectors on the ECM (if you run a 727 or manual trans)
 
Well after looking at some or the mods I have seen I think if I do this swap I will for now use a 727. No offence to anyone here but I just cant get with cutting and welding on structural components of a 40+ year old car. So I will be looking into what is needed for the hemi and the 727. My 727 wont work so 1. I have to find a used SB 727 That shouldn't be too hard or too expensive. Then a flexplate? Not sure where to buy this. And if I cant use the 03 ECM then I probably cant use the 03 harness. So 3. Different ECU and harness. 4. Oil pan and pickup. These summit have. Engine mounts for my K-frame. I have seen several offered but some if not all require special headers. I have heard the 03 truck manifolds will work but need to find out. The 03 engine is not drive by wire so that shouldn't be an issue. but transmission kick down might be an issue. Anyone out there feel free please to tell me where to get the best deal on these items and also anything else I might need. Lastly I want to get rid of the AC compressor as I don't have or want AC. And the way the belts run it looks like this could be another issue.
THanks
 
The flexplate is ATI part# 915685. Summit and Jegs both have them, no big deal. The only consideration is that it's drilled for a converter that uses 3/8" bolts, so keep that in mind if you haven't bought a converter yet.

My low stall JW converter uses the smaller 5/16" bolts, so I needed bushings to adapt the smaller bolts to the holes. I was going to have a set made up on a lathe, but it turns out that Modern Muscle sells the same flexplate, with the bushings as part# MM5761FP, and had it to my door in a few days. Problem solved.

The only other thing to consider is that the end of the crank on the new motor has a bushing in it that needs to be removed so that the pilot "nose" on the converter can seat all the way. I had to cut mine out with a die grinder; took about 15 minutes. Some have been able to weld a bolt to it and yank it out with a slide hammer, but I didn't have any joy that way.
 
if the starter is on the drivers side TTI headers have some that will fit. STREET PERFORMANCE has the pulley to get rid of the a/c and they have the kit for the kickdown for the 727. like a few here said already 05 ram computer and MODERN MUSCLE has the pedal and wiring harness. the harness is from HOTWIRE and it is nice, all labeled had everything plugged in about 20 min. i got the 6.1 with the 6 speed with a 3:55 sure grip and got 24mph on the interstate. good luck with the build, usarr
 
Thank you all for very helpful information! I think just for the sake of making my Charger drivable and enjoyable I might take the plunge here and for now go with the hemi and just use the 727. And may later on try an over drive on it. Anyone reading these posts please feel free to chime in with more input and more vendors to supply the needed parts as well as any parts not mentioned. Merry Christmas and again thanks!
 
Fyi your 03 engine IS drive by wire. I have an 03 in my car and run the drive by wire throttle which was factory.
 
Thanks

kb67mopar said:
Fyi your 03 engine IS drive by wire. I have an 03 in my car and run the drive by wire throttle which was factory.
Click to expand...

Thanks, So far everything is still in the truck. And it will stay that way till I figure out which way to go. At least I have the whole truck so I can use what ever will work. I want to leave it intact till I have all the information needed. This way if I don't go with the swap I can sell it all and it runs just as it is. So easier to sell :>)
 
JHCain said:
The flexplate is ATI part# 915685. Summit and Jegs both have them, no big deal. The only consideration is that it's drilled for a converter that uses 3/8" bolts, so keep that in mind if you haven't bought a converter yet.

My low stall JW converter uses the smaller 5/16" bolts, so I needed bushings to adapt the smaller bolts to the holes. I was going to have a set made up on a lathe, but it turns out that Modern Muscle sells the same flexplate, with the bushings as part# MM5761FP, and had it to my door in a few days. Problem solved.

The only other thing to consider is that the end of the crank on the new motor has a bushing in it that needs to be removed so that the pilot "nose" on the converter can seat all the way. I had to cut mine out with a die grinder; took about 15 minutes. Some have been able to weld a bolt to it and yank it out with a slide hammer, but I didn't have any joy that way.
Click to expand...

Cool so I am thinking of going with the 727 SB trans. What engine mounts should I get and from what supplier? If there is no ECU for the transmission what ECU would work for just the engine? And what harness? Would I need to have it flashed to work? Going this way I could use my original dash so would help it be more simple.

- - - Updated - - -

Also can someone tell me where to get another idler pulley to get rid of the AC compressor? If I cant use the ECU out of the 03 truck Any chance I could use the harness out of the 03 truck?
 
I had thought about using the 03 harness and you probably can but will have to strip it down. It has been done but you will want a factory manual to find out what wires do what. Also I'd stay away from the 03 ECM as previously stated and pick up an 04-05 ECM. Now that being said not sure the 03 harness has the same pinouts or connectors as the 04-05. I had mine re-flashed to run the manual transmission tune...if you tried to run anything but the stock trans with the automatic tune you would only get 3k rpm before the limiter. So yes, a reflash is inorder. You can pick up an ecm off of www.car-part.com pretty reasonably and find one local.

For the engine mounts the only good ones I have heard of are TTI's and are only $133 for the set. I think I heard you need the stock rubber mounts to add to that and my have to trim one...but somebody chime in here since I made my own.

As for the AC pulley...I just went to the local salvage yard and pulled a couple pulleys from a 4.7 in the yard....moved one up to a threaded spot on the timing cover and found a belt that worked with my new arrangement...didn't cost me anything but the belt.

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I found the belt by cutting an old belt and taping it together (as in pic) and then went to the store and had them measure...I got one slightly shorter and then tried it...first try worked great. (I can probably get you the part number if you want) If you do this all you need to do is add about 3 washers behind the pulley to get it spaced properly from the timing cover.
 
Ok guess I am taking the plunge. Heaven help me (and some of you guys that have gone before me) I bought a 727 SB transmission today. Step 1. Now I ask about the torque convertor. The one with the transmission I bought came from a 360 (1974). It has a couple weights on it. Do these need to be taken off? Or will this convertor even work? I don't really care too much about putting a performance convertor or anything else that is an increase in performance part in my charger. I just want a nice drivable car in the end. I think at 345 HP that is plenty as the 440 in it now is only 375HP. I know I need motor mounts , different pan and pickup , and an adaptor for the flex plate. I have the truck exhaust manifolds and I think with a little modifying they will work from what I have seen. Not worried about kick down at this time just the basics. And from what I have read here I cant use my 03 computer or harness. So please jump in with anything else I need on my shopping list. I want it as simple as I can get it and of coarse as reasonable as possible but I want a dependable car in the end as I plan on using it as a long distance cruiser.
 
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