[rockystock]

TL/DR: First Start Here

Walk-around @500 miles and short rev in the driveway: https://www.jkowners.com/forum/showthread.php?p=4470114


This might be the second or third hemi swap thread with a manual transmission out here, so hopefully this will be useful to some of you out there who refuse to slushbox your hemi haha. I’ll try not to duplicate too much from other threads because if you’re seriously considering this project, you’ve probably already read and re-read all of the others (you know you have).

So why a hemi, why not LS? It all came down to the stick. LS engines are mostly limited to the NV4500 which some have said is a little truck-like, especially with its low 5.61:1 1st gear (stock NSG370 is possible, but you’d need a TJ bellhousing and the trans is fairly weak anyway). The Getrag 238 is geared similarly to the NSG, and even though their input torque rating (300 lb-ft [EDIT: torque rating might be closer to 400 lb-ft, hard to tell, limited info...]) doesn’t inspire confidence behind a ~500 lb-ft hemi, I haven’t seen very many complaints about failures online.

Here’s a list of the things I did that you may not have seen before:
•Group 31 Odyssey battery, with Odyssey battery hold-down bracket kit
•4/0 cables for the starter-to-battery, alternator-to-battery, and engine-to-battery ground
•Oil catch can
•3.6 JK fan conversion (and mods to make it fit!)
•AEV snorkel (and DIY coolant reservoir)
•DIY lower radiator hose
•SRT / Hellcat exhaust manifolds
•True dual exhaust with: Magnaflow 59959 catalytic converters; Yonaka 304 stainless bellows flex couplings; Magnaflow 10792 x-pipe; Vibrant 1795 bottle resonators; Spintech 9000XL Super Pro Street mufflers; and Nameless Performance double-walled exhaust tips.

…And also some other mods:
•Teraflex 2WD Low TC conversion
•Rock Slide Engineering TC brace (modified for stock rear driveshaft)
•PSC pump, reservoir with large cooler

I’d recommend having a second driver while you’re working your swap. My project started in January 2017 with an engine purchase, the Jeep has been in the garage since February 2018, and as of late November I still have maybe another couple of months to finish the exhaust. I spent many hours doing other things, you know, while I had the access. Things like a front axle rebuild (new u-joints, added a truss, new unit bearings, added anti-flop tie rod joint caps), transfer case mods, hood vents, lots of diy mods etc. Although, if I didn’t have the second car, I probably would have finished it in a week or so haha. Choose your poison!

 

[jss]

This sounds like a great idea, why not a Hemi and a 6 speed, no stock LS can keep up with a stock 392. Keep up the great work!

 

[rockystock]

1. Get an Engine.

First thing I did was to get an engine. Sounds easy because it is. Maybe too easy? Obviously, learn as much as you can about the engine's history. If you're sourcing a crate or remanufactured, or if you're planning to rebuild a core, it gets very straightforward. For every other source, do this one thing at a minimum before you buy: check the VIN for the donor vehicle. Don't have the VIN? Here's how to get it with just the engine:

1. The engine serial number is on the left valve cover sticker and probably starts with "TNXE..." If no sticker, the serial number is also stamped on an engine block flat on the lower right side near the oil filter mount.

2. There is also a partial VIN located on another flat on the left side just forward of the bellhousing mount behind the starter motor location. The partial VIN will look like "J*GH######" and you may need a wire brush and flashlight to be able to read the stampings.

3. Contact Mopar, tell them you're looking at purchasing a used hemi engine, ask them to send you the VIN for the given engine serial number and partial VIN.

4. Check the full VIN against the National Insurance Crime Bureau database: https://www.nicb.org/how-we-help/vincheck

5. Also check the VIN against Carfax for good measure and possibly some recorded maintenance history.

I learned all of the above the hard way. I purchased my engine from a fellow on ebay, but at the time I didn't know about engine serial numbers and VINs. After a couple of months, I found the partial VIN and ultimately discovered that my engine was stolen. I was lucky - everything worked out over a couple of months. I contacted the police, the original seller paid me back, and since I already had the engine at a shop for some repair work, I purchased the engine again from the rightful owner at the time (an insurance company - they also said that the rest of the vehicle was still missing, but a few weeks later said the shell was found with little else). I also requested and received a notarized bill of sale from the company. Is it hot in here? Naw it's just my engine. OK that takes care of the most important engine stuff.

It's also good to try to get some sense of the engine's health beyond odometer reading and what kind of oil filter is on it now. Not sure what to add here, because I thought I was looking at a healthy engine. I was able to get a compression test done by the original seller and it came back fine. The vehicle had only about 10,000 miles and was a year old. In short, a couple of the exhaust ports were shiny with some oily residue. I also performed an engine leakdown test and found about 15% leakage past the rings in a few cylinders.

Took the engine to a shop and they said that four of the piston oil seal rings weren't even touching the cylinder walls! I suspect that's also known as poor manufacturing, and may be a big reason as to why the LS tends to have a better reputation for reliability. The shop did a very light cylinder hone, replaced the rod and main bearings, and installed a new set of piston rings.

After getting the engine back from the shop, I decided to get rid of the MDS lifters and found another potential problem, this time with the pushrods and rockers. Six of my pushrods (and their corresponding rocker cups) were scratched, and all of the pushrods were short and not very straight. I ended up getting a new set of rocker assemblies (they don't sell individual rockers to my knowledge), and a set of Manton pushrods.

 

[rockystock]

2. Get a Getrag 238

Next: getting the transmission. I've heard that sourcing a Getrag 238 can be among the hardest parts of this swap. Not here. Initially I had resigned to trying to get a professionally rebuilt trans. Called Midwest Transmission inquiring about it, and they said they had a brand new one in stock. It certainly was not cheap, but it was literally thousands less than some of the postings you can find on ebay, pitched as the one to use for a JK hemi swap. So I ordered it and it arrived at a nearby R&L Carriers location. If you get one like this, bring at least a small SUV and it will fit in the back with seats down. Don't bother bringing your trailer like I did.

 

[rockystock]

3. Get A "Kit" and Start Collecting Parts

Next up was sourcing a "kit." Not many options available for the manual trans. hemi. I used the following JSS Truck Hemi kit parts:

- Engine weld-on frame brackets
- Transmission mount adapter and A/B plates
- Intake manifold inlet adapter
- Wiring harness and PCM
- Replacement fuel line
- Dual battery tray
- Transmission cooler mount brackets (for my P/S cooler)

Everything else was either sourced from Mopar dealers / sites, or other aftermarket companies. I'll try to link my parts worksheet - it has all available part numbers and notes, and it took me quite a while to piece together all the correct parts from various dealer databases, bouncing between a 2008 JK, to a 2007 Dakota, 2012-ish Ram, 2016 Challenger... Please don't follow my list blindly; check the parts yourself. Would you trust your build to some whacko you've never met who might seem to know what he's doing? I'd definitely recommend going with the Mopar fasteners wherever possible, or even better, ARP if you can't get factory parts. It was pretty impressive seeing all the different bolt strengths applied here and there, 8.8, 9.8, 10.9... You don't want to get caught with an inferior set of fasteners in a critical location... Here's another tip: when your parts arrive (especially the fasteners), just write what they're for on the bag/package as soon as you get them, then chuck them in a plastic bin until you're ready to start swappin' for real. Oh, and mark your worksheet that you now have them in hand. I colored my parts "hemi orange" on my sheet as they made it into my collection. Fun for nerds.
https://www.dropbox.com/s/dlibdm79df0x1iz/2018-11-22%202008%20JK%206.4%20Hemi%20Conversion%20BOM.xlsx?dl=0

 

[rockystock]

4. Prepare Engine and Tranny for Marriage

Preparing the Hemi.

Chances are, the pilot bushing on your crankshaft isn't compatible with your Getrag 238, so you'll have to remove it to make room for your new pilot bearing assembly. If you happen to have the right tool for this job, well then I'm a little jealous [EDIT: the correct tool is called a blind hole bearing puller and you can get a set at Harbor Freight for cheap, or online]. If not, then thread your old flex plate bolts back in to avoid damaging the threads, and simply weld a big washer on to the outer edge of the bushing, weld a big nut on to the washer, and thread a big bolt through the nut. I'd recommend MIG or TIG for the welding; stick welding left a bunch of spatter and soot that I had to file / clean off. Drive the bolt in, pressing against the inner rear of the crankshaft, until the bushing is pushed out.

Clean up the inside of the pilot bushing area, and "press" the new pilot bearing assembly in. I tried freezing my new bushing, but it still was a bit of a shitshow tapping it in. It's straight as far as I can tell.

 

[rockystock]

Preparing the Engine (cont'd)

Next, look closely at the crankshaft mounting surface for any raised areas, especially around the flywheel bolt holes. May have to file and/or sand down the high spots.

When you're satisfied with the surface and cleanliness, check the flywheel's mating surface as well, and place the flywheel on the shaft (it goes on only one way - asymmetric bolt pattern). Check your new flywheel bolts with a thread chaser nut (check and clean the crankshaft threaded holes as well), and make sure your bolts thread in to the crankshaft with little to no resistance.

Once your bolts are ready to go, apply just a very light amount of blue loctite to the bolt holes, and maybe a very, VERY light amount to the bolts themselves. The slightest amount of excessive loctite will exit the holes and smear all in between the shaft and flywheel - not good. I torqued my bolts in three steps of 25, 50, and 75 lb-ft.

Next, you should check the flywheel runout using a dial/digital indicator (digital indicators suck). Remove one spark plug per cylinder to make this part easier.
Turn the crank (always clockwise when looking at it from the front) with a breaker bar on the pulley bolt, and watch the indicator to see the largest runout. Just FYI, the crankshaft has an endplay spec. of about 0.009", so as you turn the shaft, the shaft will probably move forward and backward. I rotated the shaft until the indicator was at the "lowest" point, then gently tapped the rear of the shaft forward with a rubber mallet, and then zeroed the indicator. Rotate the shaft in little increments, stopping to gently tap the shaft forward, and monitor the indicator.

If you're getting any more than about 0.003" of runout, then try placing the indicator in a different spot on the block. If you're still consistently high, then you may have a little high spot either on the flywheel or the crankshaft. I ended up removing the flywheel and hand sanding the flywheel mating surface where the high spot seemed to be. If you haven't done it already, you may want to also check the crankshaft runout and endplay. There isn't much metal there to allow an indicator to ride around the bolt holes, but you can check the side of the flange pretty easily. The crankshaft should be within 0.011" (11 mils) of endplay, and 0.0002" (that's 0.2 mils) for out-of-round. The measurements from my cheap indicator didn't suggest any major issues with the shaft; everything seemed to be in spec. Final flywheel runout for me was about 0.003".

Put your gloves on, clean the flywheel thoroughly with alcohol and maybe acetone, and get the clutch on. Won't bore you with clutch install; pretty straightforward.

 

[rockystock]

Preparing the Trans

Next up: transmission prep.

This is pretty simple, just clean out the inside of the bellhousing, drop the shift fork in, apply the clips, lightly grease the pilot bearing and input shaft, and you're done.

I used "High Performance Grease" made by Sachs in Germany. This one tube is probably enough for 50 transmission jobs.

 

[rockystock]

5. Assemble Engine to Trans

Bolting the transmission to the engine is yet another very straightforward process. So simple, in fact, that there's plenty of opportunity to ensure the mating surfaces are clean of all dirt, rust, and paint. I used a razor blade and gently shaved the little rust off of the block surface, then lightly sanded and wiped down with alcohol. I also cleaned out the bolt holes and deburred the bolts as needed. Again, use just a little blue loctite in the holes. Once the upper six bolts are in, install the dust shield and the structural dust cover.

Oh by the way, in the second photo you can see the flat where the partial VIN is stamped.

 

[rockystock]

6. Start Digging in to the Jeep

This is a good point to start working on the Jeep. Several excellent threads cover this process so I won't duplicate here. I will say that I was able to pull the engine, trans, and TC in my little 2-car garage with a low ceiling. Just make sure you have enough room to roll the engine hoist around while the Jeep can still move under its own power. Put some masking tape over every electrical connector that you care about; it's going to be getting dirty.

 

[rockystock]

Prep the Engine bay

Engine Bay Prep...

Now for the really dirty part of the swap, especially if you're going with the weld-in engine frame brackets. Safety first: I used a face shield, over a respirator and safety glasses, over my Rx glasses, with a welding jacket, welding gloves, bib overalls, and composite toe boots. Spending ~3 hours in the ER waiting to have a tiny piece of metal removed from your cornea is no fun, especially after having worn double eye protection. No eye injuries this time around.

Cut the stock engine frame brackets completely off and grind until the frame rails are smooth. I used an angle grinder and a cold chisel / sledge hammer. Most of the brackets that stick out from the frame can be removed with a cutoff wheel. for the portions sticking close to the frame, I sectioned them into ~1" pieces with the cutoff wheel (be careful not to cut into the frame!) and alternated between grinding the welds and chiseling the pieces off. It was a good stress-relieving experience.

I also removed the control arm brackets in preparation for a long arm install.

Tack the brackets into place and always, always perform a test fit of as many components as you can before fully burning them in. My brackets didn't line up with the frame holes quite like they were supposed to. It looked like the left side bracket was too low. Test-fitting the engine showed that not only was that bracket OK, the right side bracket needed to come up by over 1/4" in order for the engine to sit level with the frame. So I cut the tacks off the right side bracket, welded some 1/4" steel plate to the top of the frame rail, and tacked the bracket in again. Much better fit.

The bottom piece of my right side bracket was also a little crooked, so I cut it off and re-welded it on straight.

 

[rockystock]

7. Making the SRT Headers Work

Go with the SRTs, they said. They're worth it, they said...

Here are the changes I had to make for the car (not Cherokee) SRT manifolds:

1. Remove some material from the rear vertical plates on the engine frame brackets. I took enough off to work with the engine in either set of holes.

2. Engine in upper engine bracket holes. Raises the engine about an inch so the headers will clear the frame rails.

3. 1-1/4" body lift. allows the hood to clear the truck intake adapter (possibly also the alternator). [The body lift also helps the shift tower boots fit like the stock setup.]

4. Massaged the left header collector near the starter motor. I used a 36mm impact socket and a sledge hammer to gain just enough clearance around the starter to fit the exhaust flange flush on the head. Engine Masters said it was OK, so... https://www.hotrod.com/articles/engine-masters-ep-4-bashes-headers-for-horsepowerso-you-dont-have-to/

5. Added a second 3/8" exhaust flange and second gasket (on the left side header only). The massaging and spacer netted me ~5/16" clearance around the starter. Still very close, so I also added some heavy duty thermal wrap on the starter.

The alternative to all this work, and still have better flow than the log manifolds would be a fully custom fabbed set with probably a ceramic coating. AFAIK at this time there are no off-the-shelf headers available for this setup. However, now that I've done it this way, I'd probably just plan for custom headers next time around. I'll update this thread if I have any issues with this setup.

In the last photo you can also see the 4/0 cables routed to the starter and engine (actually bellhousing) ground.

Here's a video of the header fitment:

 

[rockystock]

8. Checking Shift Tower Clearance

Checking the Shift Tower Clearance

As I mentioned earlier, the 1-1/4" body lift was a workable solution to the shift tower fitment as well. Before the lift, the lower shift boot wouldn't fit between the tower and the metal plate. Below you can see some photos of the tower before the lift (no after pics - sorry!).

 

[rockystock]

9. Shift Stub Modification

Shift Stub Modifications

The Dakota shift stub and lever are fairly long and point low and in toward the driver seat cushion. The lever actually hits the TC shift knob especially when in 4-low. To solve this problem, I sent the stock shifter and Getrag shift stub to Cleveland Power & Performance. I didn't feel confident doing this mod myself, and probably would have melted the plastic shifter ball. CP&P took my request and swapped the top of the stock stub onto the Getrag lower stub. I had seen that they did this on their JK hemi/manual swap back in 2015 I think. It turned out excellent!

I also installed the B&M shift lever mostly for looks. Could have used the stock NSG lever, but I think it really looks good now. Putting in a few Scat Pack easter eggs here and there.

I'd recommend trying to source a shift tower from a Ram G238. Not sure but I think the Ram stub may be shaped differently and work better than the Dakota version. Keep in mind if you get a Ram trans you'll have to convert it to use the rear tower hole.

EDIT: Additional info/pics of the modified stub here: https://www.jkowners.com/forum/4456328-post46.html

 

[rockystock]

The foam piece on the stock shift tower didn't fit with the Getrag, so I made a new one from a 12" x 12" x 3" piece of NRS Minicell Foam. The foam is a closed-cell high-density type and feels similar to the stock insulator.

In the pics, you can see that I had the insulator sitting right up to the top of the floor plate. I had to trim the insulator a bit more off the top so that the lower shift boot could snap into the hole properly.

That's it for the transmission; everything else is plug-and-play.

https://www.nrs.com/product/2076/mi...vah3DTidN7cD-x669ONkxASCZi77ou30aAmKqEALw_wcB

 

[rockystock]

10. Heat Management Mods

Heat Management Mods

After reading several threads on both the Hemi and LS swaps, it looks like overheating and various coolant system failures can be difficult to solve. Here's what I've done in this swap:

1. Manual Trans (lol). The absence of a trans. cooler will probably help.

2. SRT manifolds. Freer-flowing headers should help get the hot exhaust gases out of the engine more efficiently, reducing heat load on the cooling system. The SRTs also have integrated heat shields which should also help with under-hood heat.

3. C&R radiator and 3.6 JK Pentastar fan conversion. Because of the placement of the engine and the longer truck hemi timing cover, this mod required some clearancing to move the radiator forward about 1/2".

4. AEV snorkel. Not crazy about a snorkel, but it should definitely help get air - as cool as possible - into the engine. Apparently, an intake drawing hot air from under the hood could cause the computer to pull timing in response to the hotter intake air, which can cause the engine to run even hotter, leading to hotter under hood air etc... The snorkel requires the stock air box, so the setup also removed the fairly large space available on that side for the TJ coolant reservoir, so I had to make my own reservoir.

5. Fender and hood vents. Whether JK Chevy or JK Hemi, there's so little space behind the fan, it's a wonder these conversions cool at all. Venting should reduce the air pressure behind the fan and in the engine compartment, aiding in airflow / cooling both at speed and on the trail.

 

[stevenjoh1972]

For the open air space, just left or right of your headlights, fill it in with some aluminum or rubber. This will force the air tree through the radiator and help cool even further.

I have a whole thread out there on how I went from 234 on a 100 degree day without AC running to 203-212 on the same day with the ac blowing on high, and recirculating the interior air.

Sent from my SM-N950U using Tapatalk

 

[rockystock]

Radiator Support Mods

Radiator Support Mods

Here's what I did to gain enough clearance for the 3.6 fan:

1. Cut 5/8" off the back of the upper radiator support brace. That was the most I could remove and still have the holes for mounting the grill cover. I used a cutoff wheel and a little grinding to deburr.

2. Weld on a strip of steel 1-1/2" x 3/16" x (length to fit the notch). You can get the steel from Home Depot or Lowes. Make two small additional pieces to weld to the ends and fully close off the brace. I also welded a small rectangular piece to the back side of the ends, where the upper radiator bolts will thread in, for extra fastening strength.

3. Add aluminum spacers to the front of the lower support bracket. These spacers move the bottom of the radiator and support by about 1/2" or less. I had to grind them down a little for the best fit.
- 4x McMaster-Carr spacers, # 92510A821
- 4 pieces of 1/2" copper water pipe, ~3/4" long
- Clear Gorilla Glue
- Clamps
- Drill out ~5/8" into the support bracket holes. Use a bit to allow the copper centering pieces to fit snugly (my tubing measured exactly 5/8")
- glue and clamp the centering pieces and spacers to the radiator support bracket.


In addition to the mods above, I also added a compression spring to the upper radiator supports, as discussed in other threads. The purpose of the springs is to help protect the radiator from cracking as the front of the jeep flexes and twists the radiator supports. Here's my parts list:

- 2x McMaster-Carr shoulder screws, # 92981A210
- 4x McMaster-Carr dry sleeve bearings, # 6627K409
- 2x The Spring Store stainless compression springs, # PC063-540-10600-SST-1750-CG-N-IN (https://www.thespringstore.com/pc063-540-10600-sst-1750-cg-n-in.html)
- 4x washers (to fit on either end of the springs)
- 2x fender washers (to fit over the rubber isolators)

Also, I cut off the water pump threads for the mechanical fan. Go slow with the cutoff wheel and spray lots of water on the hub while you're cutting.

 

[stevenjoh1972]

Awesome!!!

Sent from my SM-N950U using Tapatalk

 

[rockystock]

Coolant Reservoir DIY

Coolant Reservoir DIY

The AEV snorkel very effectively deletes space for a stock TJ coolant bottle. So I decided to make my own bottle. This one was made from 16ga 304 stainless, three stainless 1/4" npt female bungs, and a 1-1/2" fill bung and cap (I ordered all the bungs and the cap from Bung King). The radiator recovery tube connects to the bottom and uses a 1/4 NPT to -4AN 180-degree push-loc fitting. One bung on the lower side connects a 1/4" silicone sight tube. The top bung connects to a tee for the top of the sight tube and the overflow drain line.

The 2" strip sides were made first. I started with the curved section. Use a sheet metal bender to provide a precise curve radius. I don't have one of those so I improvised in the garage, with a propane tank and also my drill press round table. The straight sections of the sides were bent using a Harbor Freight 30" manual bender.

I punched the bung holes using some knockout dies and a hand press.

Fitting the wall pieces to the 2" sides was a tedious experience and took two weekends to complete and leak test, but I'm happy with how it turned out. This was my first TIG welding project and was a lot of fun. I now have a full 75 ounces of reservoir capacity, not far off the stock 3.6 reservoir, and about an inch of clearance from the engine accessories.

This reservoir also has lugs welded on to the front to attach just like the stock bottle, so removal is just as easy.

I used a DC tig welder, and with no fancy welding table (yet?) I just used a 20" x 30" piece of 1/4" steel plate (removed the pickling with a belt sander) over a piece of scrap butcher block, all held up by an old plastic folding table. I survived