If you do go the LS route, I would advise against getting a random 4.8/5.3/5.7/6.0/etc. from a junkyard or random seller and just throwing it in. A lot of people, mostly on the internet, think there's nothing wrong with that, and a lot of times people get lucky and can pull that off. But I would at least do a basic rebuild or buy something rebuilt from a reputable source so there's less likely to be issues.

LS's are just another engine, and while they are very good engines, they still have their failure points. Lifters failing and destroying the cam lobes are probably the most common. To replace the lifters on an LS requires head removal. To replace the cam requires you to have enough room to slide it out from the front of the engine, so if it's in the vehicle already, you're looking at a minimum of removing radiator and everything else on the front end.

I've had lifter failure of my own which wiped a lobe (most likely due to previous owner neglect), a spun rod bearing (from my own neglect) and even a spun cam bearing in a higher milage iron 6.0 with a bent valve and nasty seats to seal the deal. Hell, a 5.3 I pulled from a junkyard unknown miles truck had the rings gunked completely up and it would have caused piston knock (could rock them back and forth in the bore by hand) and oil consumption issues had I just ran it as is. Pretty much all of these are oil related issues, so ensure good oil is used, proper level at all times, good oil pressure, and changed on time with good filter. Alot of the higher mileage ones love to suck oil into the intake manifold via pcv system, as in puddles of oil just sitting in bottom of manifold, so be aware of that as well. At least run a catch can to prevent it as much as possible. Leaking rear main seals are pretty common too.

Again, just my advice as an LS lover. I hate this whole fad of "taking it apart lets the magic out". You can rebuild an LS for less than a grand easy if all the major components are in decent shape and you do it yourself. New rings, bearings, gaskets, seals, and even cam and lifters if needed. Could get lucky with a random engine, but it's up to you to take that risk.

 

i am starting to get gun shy about the LS swap. If i am going to buy the kit, buy a motor, rebuild it and go to all the trouble to make it fit maybe making the 4.0 might be the best option. I might just do the heads, do a valve job, clean the block and get a quality head gasket with head studs or the torque bolts. I tend to lean towards head studs just because of my experience with them. Also, an inline thermostat probably wouldnt hurt. I plan on keeping it for sometime being how i have never had the ability to buy one with all the goodies already on. As you know a lot of these add ons for Discos are really expensive compared to jeeps. It really is an interesting topic that pops up about these motors and their cooling issues.

 

What 11chuck above says is true. I have a junkyard LS, but I chose carefully. I found a reputable place, found out the history of the vehicle it was in and figured out why it was in the junkyard, and paid a bit more than your average engine from Facebook Marketplace. I also replaced some common seals, the water pump, and generally went through the engine before it was installed.

 

this might be a dumb question to ask.... how do you determine what thickness gasket to order? Cometic seems to have a lot of different thicknesses

 

I wanna say 0.040 is close to stock gasket compressed thickness but not 100% on that. Thinner or thicker will alter compression ratio, but may throw off alignment of things like intake manifold to heads as well as possibly altering pre-load of lifters which would need addressing with different pushrod lengths if out spec, etc. Lot to think about when going to different head gasket thickness sometimes.

In theory, just a decrease in gasket bore size alone will actually slightly raise the compression a hair. As long as the 94mm gasket doesn't overhang into the cylinder bore or combustion chamber, should be good to go. Apparently others have run it just fine. Maybe someone who has done it themselves can chime in.

 

I assumed the thickness difference was to take up what was machined off of the head in resurfacing. Which I think is becoming an issue with our rovers since most have had several head gasket jobs already and don't have any material left to take off the head if they need resurfacing. I don't know the measuring process to see how much has been previously removed.