Ls swap ???

[b00sted]

Thinking of an ls swap but am wondering what trans to use and will it connect to the transfer case in my 1987 Grand Wagoneer that has the 727 currently in it.

[sierrablue]

I'd just go with a 4, 6, or 8l60e and swap in an np241
with it. You've got to watch gas tank clearance a little but the 4 will fit.

I think there's an adapter to run the np228/229 behind it but it's not cheap. If your stock np229 has a bad viscus coupling then I'd definitely just swap it. If nothing else I'd go to a mechanical shifter rather than the vacuum one. Simplifies things a bit and it's a lot more reliable.

Just my .02. Obv not my truck tho

[dodgerammit]

What shape is the 727 in? Mileage on it? Mine was freshly rebuilt with a trans go kit and Hughes low stall convertor, so I kept it and only put in the motor via an adapter from Advance. If going this route, your motor needs to be DBC so you can control the 727 line pressure via a kickdown cable. Everyone who said I'd regret keeping the 727 couldn't have been more wrong. I can adjust the shift points via a simple cable adjustment, and I don't have to worry about speedo control adapters, multiple neutrals from the 4L60s, etc. I now am approaching 15K miles on the swap with no issues. Initially, I kept the 229, but later swapped to a 242 since the viscous was showing early signs of failure.

My thread is in my signature if you want to read up more on it. Swap starts about page 5.

[sierrablue]

What shape is the 727 in? Mileage on it? Mine was freshly rebuilt with a trans go kit and Hughes low stall convertor, so I kept it and only put in the motor via an adapter from Advance. If going this route, your motor needs to be DBC so you can control the 727 line pressure via a kickdown cable. Everyone who said I'd regret keeping the 727 couldn't have been more wrong. I can adjust the shift points via a simple cable adjustment, and I don't have to worry about speedo control adapters, multiple neutrals from the 4L60s, etc. I now am approaching 15K miles on the swap with no issues. Initially, I kept the 229, but later swapped to a 242 since the viscous was showing early signs of failure.

My thread is in my signature if you want to read up more on it. Swap starts about page 5.

My 2 issues with keeping the 727 are/would be number one, with an LS you already have all the computer stuff you need to have it talk to the electronic transmission, and number two, one of the biggest issues with the stock SJ drivetrains is that they never bothered to put an OD in it. Mileage killer right there, and it wears out your engine faster because it's spinning millions more times per couple thousand miles.

The guys keeping the stock powerplants want to go TO the electronic transmission (or at least overdrive) because they're really good when they're dialed in, and they have the O/D. If you're swapping the engine anyway to something that communicates to the transmission, it seems to me like that would be the way to go.

I've read your thread dodgerammit, and I understand why you did it, with a brand new tranny and all. But for most LS swaps...

[dodgerammit]

What shape is the 727 in? Mileage on it? Mine was freshly rebuilt with a trans go kit and Hughes low stall convertor, so I kept it and only put in the motor via an adapter from Advance. If going this route, your motor needs to be DBC so you can control the 727 line pressure via a kickdown cable. Everyone who said I'd regret keeping the 727 couldn't have been more wrong. I can adjust the shift points via a simple cable adjustment, and I don't have to worry about speedo control adapters, multiple neutrals from the 4L60s, etc. I now am approaching 15K miles on the swap with no issues. Initially, I kept the 229, but later swapped to a 242 since the viscous was showing early signs of failure.

My thread is in my signature if you want to read up more on it. Swap starts about page 5.

My 2 issues with keeping the 727 are/would be number one, with an LS you already have all the computer stuff you need to have it talk to the electronic transmission, and number two, one of the biggest issues with the stock SJ drivetrains is that they never bothered to put an OD in it. Mileage killer right there, and it wears out your engine faster because it's spinning millions more times per couple thousand miles.

The guys keeping the stock powerplants want to go TO the electronic transmission (or at least overdrive) because they're really good when they're dialed in, and they have the O/D. If you're swapping the engine anyway to something that communicates to the transmission, it seems to me like that would be the way to go.

I've read your thread dodgerammit, and I understand why you did it, with a brand new tranny and all. But for most LS swaps...

Depends on the tune. In my case, the LS engine guy had a non-electronic trans/manual trans tune. Yeah, you can tune for whatever, but tuning costs $$$. If you want a 4L80 behind a motor that had a 4L60, you gotta buy the minimum 2 credits (at $50 each) and reflash the PCM to accept it. It's not as plug and play as people think it is. You can easily end up spending several hundred on just tuning.

The best bet is finding a 4wd donor and using everything. Still gonna spend 2 credits to flash the PCM to do the rear O2 delete and Vats delete. (It's minimum 2 credits per tune).

Mine is getting the same mileage as the guys who did the OD trans. The big issue everyone misses is; to truly take advantage of the OD you MUST regear. Otherwise OD is useless, even with the 3.31 ratio. I've even tested the mileage on ethanol fuels with no drawbacks. Knocking down 16-18mpg average right now.

As far as wearing out my engine faster, my engine doesn't spin any faster than someone who has the OD trans and has regeared. Basically, the 2.72 ratio IS the OD. I'm turning about 2000rpm at 55-60mph. Right where the LS is happy.

[sierrablue]

Isn't that the mileage with 33"s and 4" of lift? I mean I'm averaging 15 pretty consistently with no air dam, no lockup converter, a less efficient tranny, a carb V-8 of a similar size, with 3.54s. What I've been reading indicates like 20-22 with an LS and decent gears and OD, on an otherwise stock rig. I can't run E15 or anything but I run standard ethanol 87.

I mean if it's stock, why wouldn't you get the harnesses and/or computers from the right truck to start with? And @b00st was talking about a turbo which is going to need a different tune anyway, right?

I realize the LS likes to sit there, but at 55-60 you're already pulling 2k rpms. Mine with the 3.54s is sitting at like 2400 at that speed. Vs. a 30% overdrive which would drop it from 2400 on mine to 1.690 (plus a lockup converter so it'd be lower yet). Not the same RPM at all.

I'm not trying to brag about mine; I'm just using it as an example because it doesn't have like anything going for it in this regard, and it's still pretty much keeping up.

Why would you HAVE to regear? It has a lower first gear than the stock ones so taking off wouldn't be an issue, and it won't go into overdrive if it can't use it. It may be nicer than not regearing, but it's not required...

And when you go on a road trip at 70+ all day long, the overdrive is a MUCH nicer option. If you're not doing that not an issue but if you are...also with the turbo it may be able to hold OD longer.

I realize it has shorter tires, but my dad's '69 Cougar has 2.73s and no overdrive, and you can hear that it'd take an overdrive if it were availible.

[b00sted]

My trans is fresh with a shift kit and about 300 miles on it now. After reading all of this I think I will stick with my hemi I have in the shop and be a bit different. Yes way more expensive for a harness and tune but different. As far as fuel mileage goes this will not be my daily driver as I have the mighty Cummins for that...

[dodgerammit]

Isn't that the mileage with 33"s and 4" of lift? I mean I'm averaging 15 pretty consistently with no air dam, no lockup converter, a less efficient tranny, a carb V-8 of a similar size, with 3.54s. What I've been reading indicates like 20-22 with an LS and decent gears and OD, on an otherwise stock rig. I can't run E15 or anything but I run standard ethanol 87.

I mean if it's stock, why wouldn't you get the harnesses and/or computers from the right truck to start with? And @b00st was talking about a turbo which is going to need a different tune anyway, right?

I realize the LS likes to sit there, but at 55-60 you're already pulling 2k rpms. Mine with the 3.54s is sitting at like 2400 at that speed. Vs. a 30% overdrive which would drop it from 2400 on mine to 1.690 (plus a lockup converter so it'd be lower yet). Not the same RPM at all.

I'm not trying to brag about mine; I'm just using it as an example because it doesn't have like anything going for it in this regard, and it's still pretty much keeping up.

Why would you HAVE to regear? It has a lower first gear than the stock ones so taking off wouldn't be an issue, and it won't go into overdrive if it can't use it. It may be nicer than not regearing, but it's not required...

And when you go on a road trip at 70+ all day long, the overdrive is a MUCH nicer option. If you're not doing that not an issue but if you are...also with the turbo it may be able to hold OD longer.

I realize it has shorter tires, but my dad's '69 Cougar has 2.73s and no overdrive, and you can hear that it'd take an overdrive if it were availible.

No. A lifted vehicle with heavier tires will get poorer mpg than stock. The only way you'll get more than 20 mpg in a brick shaped FSJ is to diesel swap it. Every one on the LS swap group is getting 15-18mpg with the OD.

My T/A with the Ls1 and 6 speed cruised at 2K rpms at 55-60 as well. So, I'm going with GM knew where the LS needed to be. It's all about the torque curve.

Regearing makes it able to utilize the OD. Otherwise it's worthless. Plenty of threads out there of people who kept stock gearing and th OD only comes into play at 70mph, then will drop a gear on the slightest of grades. This is why I'm still using the 2.72s. My transmission doesn't even hit 3rd gear till 45mph. Then it's turning 1500rpm. It'll down shift at 40 mph if it's under load. Again, this is to take advantage of the torque curve of the motor. If you're rocking an OD, the same thing will happen under load at those low revs. It's not where it needs to be. It'll downshift. 1500rpms isn't where most engines run at cruise anyway. It's basically a fast idle and not enough to move the vehicle except on very flat ground or down hill.

I can road trip at 70 all day long with no issues. In fact, 65-70 is where I get the best fuel economy. I've broken 20mpg when consistently at those speeds.

I get it, you feel like you have to chime in on every thread and stir the pot.

You want the last word.

Knock it off.

Quit mucking up other's threads and questions with your opinions. I've actually done it. I've owned LS powered vehicles for going on 15 years.

I chimed in to give the OP something to read and think about based off of my ACTUAL experience. They may choose to go a different route anyway, and that's okay. If they do, I'm not going to argue with them every freaking step of the way.

[dodgerammit]

My trans is fresh with a shift kit and about 300 miles on it now. After reading all of this I think I will stick with my hemi I have in the shop and be a bit different. Yes way more expensive for a harness and tune but different. As far as fuel mileage goes this will not be my daily driver as I have the mighty Cummins for that...

Check out Termite off road's youtube channel. They are Hemi swapping their Wag. Lots of good info there. They go through dang near everything involved. I'd wager you'll get about the same mileage as a LS swapped rig. Really, it's modern tech, better timing/fueling control that allow the mileage gains. That and getting parts ANYWHERE by simply walking into the parts store. Anything for the AMC takes longer. As time goes on, parts get more scarce/expensive/take longer to get.

As far as the transmission, I'm not sure if they make an adapter to mate the AMC specific 727 to the hemi. (different bellhousing patterns) You may have to swap the guts into a mopar specific transmission. Internally, they're the same.