YJ 4.2L to 5.3L LS Swap - JeepForum.com
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post #1 of 29 Old 10-15-2020, 09:11 PM Thread Starter
biggurn
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A couple years ago I sold my 4.3 Vortec swapped YJ and have been "Jeep Free." We have a Polaris Ranger SxS, and its fun and all, but hard to beat a Jeep!

I'm a big fan of leaf springs, and since nice CJs are getting hard to buy (i.e. afford) I've really migrated to YJs for my last builds.

This time around, it'll be a 1990 YJ with 130k miles, that while it has a running motor, I'm just not a carburetor fan! I like EFI, especially living in the high desert of Idaho where we have swings from sub zero to 110 and altitude from 2000 feet to 10k feet. So, I'm an EFI guy. Now, I realize the 4.2 can be injected or a 4.0 can be swapped, but if I'm going to the effort, might as well swap a v8! And in this day and age, might as well be an LS!

My $1500 YJ. No rust in the body or chassis, just some surface patina.


The donor: 2001 Tahoe with a 5.3 LS and 135k miles. Its an auto, but I'll be going 5 speed in the Jeep, because even with a blown clutch, you can still drive home!



The pair side by side, trying to get along...



I'll be going to Howell EFI for a harness and the ECM flash. Radiator from Mishimoto and motor mounts from Mountain Off Road Enterprises.

http://mountainoffroad.com/collectio...-95-yj-with-v8

Stay tuned! Hopefully we'll have the motor out of the donor tomorrow and then we can start prepping it! Then it'll be the Jeep's turn.

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post #2 of 29 Old 10-16-2020, 05:39 AM
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Very interested in watching your progress. Those motor mounts look good - had not seen them before.
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post #3 of 29 Old 10-16-2020, 06:27 PM Thread Starter
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I'm a huge fan of their mounts. Used them on a couple different swaps, IMHO, not a better mount out there.

With the help of my eldest son (13), the engine is out. Tahoe was hauled off to the scraper. We got $150 for the Tahoe. $60 for the two catalytic converters, so at least it paid something!

Used the skid steer to lift up the Tahoe to pull the tires... was a little sketchy on the passenger rear...good thing the wife wasn't home for that one!




The engine is on the stand.




Now to get the engine cleaned and prepped to go back in.

A bunch of parts arrived today. A lock rite for the front axle, lublockers for both axles, the engine mounts, and all the fuel fittings and fuel line.
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post #4 of 29 Old 10-16-2020, 06:52 PM
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Originally Posted by biggurn View Post
I'm a huge fan of their mounts. Used them on a couple different swaps, IMHO, not a better mount out there.
I checked out their web site. Do their YJ mounts work with a Gen 1 SBC? The implication is that they do but it is not explicitly stated.
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post #5 of 29 Old 10-16-2020, 08:49 PM
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Looks like you've got a plan already but feel free to check out the engine swap in my sig if you're looking for ideas to proceed.

As for LS based motors being compatible with Gen I SBC engine mounts...they aren't the same but they're easy enough to change. LS uses 4 bolts to mount to the block and SBC uses 3. You generally use the SBC mounts and buy a $25-$35 adapter to mount them to the block. It's pretty simple and actually gives you a little wiggle room to move the engine around after everything is welded in. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


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post #6 of 29 Old 10-16-2020, 10:30 PM Thread Starter
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Quote:
Originally Posted by 11-11-11 View Post
I checked out their web site. Do their YJ mounts work with a Gen 1 SBC? The implication is that they do but it is not explicitly stated.
I guess I should have mentioned that, the kit I linked to includes the engine mounts for the original 3 bolt SBC pattern. You have to order their LS plates on top of the mounts. Makes them a little more spendy, but the adapter plates like what was shared above, make the mounts to wide to use the standard 3 bolt SBC mounts.
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post #7 of 29 Old 10-17-2020, 04:24 PM Thread Starter
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Well, I went NV3500 shopping with my eldest today at all the local scrap yards and learned that a 2001-2006 Chevy/GMC K1500 4x4 with a 4.8 and NV3500 is an exceptionally rare combination. So rare, none had ever even seen one! So, that tosses the NV3500 option out the window, back to Novak and retaining the AX15 it is! Hahaha. Oh the joys of power train swaps!

On the upside, we did get the Jeep into the shop today. My eldest two pulled it over with the Kubota:





http://www.youtube.com/watch?v=nblw6F9uDdE

While I have a skid steer and several larger tractors, that little B7100 Kubota is just such an amazing machine!

Last night I ordered all the tune up parts for the engine. Once the AX15 is out of the Jeep, I'll get it and the engine washed and prepped. I'll order adapter parts Monday. Fortunately, we did pickup a bellhousing while at the pick-a-part this morning!

On the upside, while cleaning out the Jeep, we found a brand new Delphi fuel pump and sock for it, that knocks some expense off my swap. Plus, the Jeep still has the cats, so I'll be able to scrap those and add that money back into the fund.

More to follow!
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post #8 of 29 Old 10-17-2020, 08:44 PM
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Quote:
Originally Posted by biggurn View Post
I guess I should have mentioned that, the kit I linked to includes the engine mounts for the original 3 bolt SBC pattern. You have to order their LS plates on top of the mounts. Makes them a little more spendy, but the adapter plates like what was shared above, make the mounts to wide to use the standard 3 bolt SBC mounts.
When I finally get around to swapping mine, I have a 'fresh' 1967 283 block, 327 crank, and SM420 (the last one with the reverse switch). I have stock 2 bbl and 4 bbl manifolds, a 2CV and a Rochester 4-jet (have not yet decided which one I will run). There will be no electronics - it will have a points distributor with a tach drive and, maybe, a generator. Don't want any solid-state anything in the 'make it move' department. Keenly interested in your swap, so good luck! You are making fast progress.
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post #9 of 29 Old 10-18-2020, 07:45 PM Thread Starter
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Sounds like you'll have a nice package when you get it together. When it comes to something I'll be daily driving, I'm just a huge fan of EFI. Especially given all the variations in our altitude and climate.

Had a little while this afternoon, so I prepped the Jeep to have the motor pulled tomorrow. All I need to do is unbolt the motor mounts and the transmission cross member/skid plate and out it'll come.
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post #10 of 29 Old 10-18-2020, 08:10 PM
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IMO, the negatives of EFI are all associated with TBI or early OBDI which were pretty crude. OBDII and especially the LS electronics have gotten so good that people have nearly forgotten that these are the same EFI's that they are holding a grudge against. These things are like appliances now... You just use it and don't bat an eye at it anymore. I never saw a carburetor or points ignition last 200k miles without being touched. I recognize that a carb engine has less to go wrong and can therefore be easier to diagnose. However, I'd argue that if you know your engine really well like the carb guru's claim they do, you know what sensors you can and can't live without. You also learn to quickly diagnose little things to rule out potential problems. I did have a MAF sensor go out on me one day out of the blue which gave me about 5-10 seconds warning that it was going out before it did... I'm far from an expert but it took me about 3 minutes without any kind of scanner to figure out what was preventing my engine from running and I drove the Jeep home without any major issues after disconnecting my "budget" MAF.


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post #11 of 29 Old 10-19-2020, 08:42 AM Thread Starter
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Even early EFI isn't hard to work with, once you spend the time to get to know it. I was a diehard carburetor guy until I was forced to work on the TBI on my little '89 S10 with a little 2.5L Iron Duke engine. After rebuilding it, and discovering how simple it truly was, my next Jeep was put together with a TBI, never looked back since. When I built my 1970 F100 hot rod a few years ago, it recieved Holley multi-port injection. Runs great and easy to tune.



In this day and age, with companies like Howell EFI offering the means to vastly simplify the EFI process, I can't imagine running a carb! The benefits way out weigh and possible draw backs IMHO.
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post #12 of 29 Old 10-19-2020, 10:48 AM
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Quote:
Originally Posted by Waternut View Post
IMO, the negatives of EFI are all associated with TBI or early OBDI which were pretty crude. OBDII and especially the LS electronics have gotten so good that people have nearly forgotten that these are the same EFI's that they are holding a grudge against.
Quote:
Originally Posted by biggurn View Post

In this day and age, with companies like Howell EFI offering the means to vastly simplify the EFI process, I can't imagine running a carb! The benefits way out weigh and possible draw backs IMHO.
I simply want my Jeep to be old-school.
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post #13 of 29 Old 10-19-2020, 07:59 PM Thread Starter
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Had a pretty good afternoon in the shop. The engine, transmission, and transfer case are out! Parts are ordered to adapt the engine to transmission.


With the engine out, I was clear to start thinning down the harness. This is all of the stock emissions and vacuum control wiring from the MCU (under the dash). Since NONE of it is required for the conversion, it all goes away.


When it is all said and done, I'm left with just the wires coming from the main bulk head connector. None of those needed thinned, they just needed pinned out so that I knew what was what for wiring into the new harness.

Tomorrow, I'll reloom the harness, reroute it, and start on the fuel system modifications (add an electronic fuel pump, new 3/8 feeder line, remove factory 1/4" return line, etc). If I have time, I'll get the 4.2L motor mount horns cut off the frame and the M.O.R.E. horns burned in with the mig welder.
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post #14 of 29 Old 10-19-2020, 08:01 PM Thread Starter
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Quote:
Originally Posted by 11-11-11 View Post
I simply want my Jeep to be old-school.
Nothing wrong with that. My '53 Chevy 6500 semi-truck is all still 6v, carburetor, and dead simple to work on! I get it.
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post #15 of 29 Old 10-19-2020, 09:04 PM
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I feed mine with the stock fuel lines... maybe that's not enough but then again, I'm not usually revving this thing very hard and even 3500 rpms is super rare for me.


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