4.8 Swap LJ
- Thread starter Shank
- Start date
Leaning toward it. A little worried about tuning but probably be fine. Half bet 5.3 tune will be close to 4.8 with cam (plus add rpm for idle).
Unless you want custom tuning leave everything stock.it isn't hard to download stock files for a given stock displacement,injectors,etc
Last edited:
I can only relate my experience with junkyard motors in the Magnum family and that didn't turn out good for me. If I was building it no matter what engine I'd at least want to check everything. That's what I did with the Hemi before I put it into my TJ. If the cylinders all look OK and the bearings are good then yes run it. But I'd replace any known issues while you have it out of the Jeep. It's a lot easier then instead of trying to do it when it's in the Jeep.
Can he put a torquer cam in it without issues? How much does the GM ECM allow? I know the Mopar PCM doesn't allow much of anything but I thought the GM ones allowed you to tweak a bit more?
LS has low tension rings and many other great features for a 300k+ motor. Screw around with more than a bit of timing and power enrichment delay and you better know what you're doing
I know the LS has some good features. I just know how my luck with engines has been. The first engine I had swapped into my TJ was a low mileage engine and it still gave me issues. Like I said better to check things out now instead of in the Jeep.
It’d be such a small cam that it’s guaranteed to run stock tune, but noted. I’m sure it’ll take some tuning work to get it perfect.
The typical opinion with junkyard truck engines on these is to never look at anything, especially the cam bearings. I couldn’t help but pull one rod bearing cap, but haven’t gone further yet.
I’m not saying that’s my personal opinion, I think the reason for it is they will have some wear and you’re likely to do more harm than good with a lot of it.
I wish it was as easy as just buying a known great engine (reman or not).
This is what I did with my junkyard motor and it runs amazing as far as I can tell - if that instills any confidence
all I really did was turn the crank with my impact and see if it had enough compression to pop out the coil packs without spark plugs.
I hope it all works out for you. I'd been told the same thing about the Magnum engines. If I got a low miles engine I would be good. While this might be the norm I didn't have such luck. First off the plenum gasket was blown (granted a common problem) and then one of the heads was cracked.
I hope the best for you, I'm just gun shy now and like to look at stuff after all my shitty luck.
I get it, I know I’m doomed with my luck. I’m building some contingencies into the plan for this.
I've got my fingers & toes crossed... My engine was a under 50K mile takeout so I was like what could go wrong...
Have you had any luck finding any help on the wiring yet? It's been 2-4 years ago there was a member on here who did the wiring himself and had a build thread.
Secretly was rooting for 4.8- I think smaller displacement it’s well suited for a DD application so a vote to keep it stock as far as drivetrain reliability and fuel range potential….however if it is more rowdy your after, I can can appreciate that!
Stand alone harness and integrating into Jeep wiring, I think I have most of it figured out. Not many relays in PDC, and I’m failing to see why I would send a 12v ignition to a separate relay to trigger ground to other relays that already have 12v ignition to trigger them.
Maybe I am missing something but why add a relay just to ground the other relays when I could jut ground them.
I think I’ll keep it stock, curious what kind of mileage I can sneak.
I am used to my 4Runner and its sufficient, though not great on power.
4Runner:
32” tires
3.73 rear gear
236hp at 5200rpm
266lb-ft at 4000rpm
LJ with 4.8
33” tires 3.73 rear gear
270ish hp at 5200rpm
290ish lb-ft at 4000rpm
Couple that with obvious advantage for lower end torque, it should be plenty fine.
Back from my weekend away. Rock Auto seemingly has lost one of my orders, so that isn’t helping.
Hopefully I understand the wiring like I think I do, wire delete is in process (yes everything is labeled). Phase one will likely have a cluster of labeled, cut, and heat shrink capped wires on drivers side coiled up. C1, C2, and C3 are no longer. C102 and C103 are next to be deleted.
Phase 2 will be depinning connectors into body and cleaning up.
Hopefully I understand the wiring like I think I do, wire delete is in process (yes everything is labeled). Phase one will likely have a cluster of labeled, cut, and heat shrink capped wires on drivers side coiled up. C1, C2, and C3 are no longer. C102 and C103 are next to be deleted.
Phase 2 will be depinning connectors into body and cleaning up.
Nice man. Really gettin' at it. This is the scariest part of a swap for me by far. I wussed out and paid someone to do it
Similar threads
