This is the list you gave earlier in one of your replies. Some of them didn’t make sense, but I think I know what you meant. I added options 6, 7, and 8 to make it complete as possible. It took me 5 hours of active typing and editing to write this.
I’m going to guess at reasonable numbers for horsepower and cost just to compare the options. Your mechanic quoted 3K to rebuild your transmission, transfer case, and install a crate motor. That means he is charging you 2K for the crate motor and 1K to rebuild everything exactly stock. It’s a lot easier and faster to put something back together exactly how you took it apart. That’s a great deal and I do not think he’ll still charge you 1K if you add the time and labor of a conversion. I’ve estimated what I think he’ll charge you in labor for each option based on that information.
You’ve stated “get a performance camshaft” at each option, but that doesn’t make much sense. There is a negligible difference between the Crane cam (Crane is a company) and the original 4.0 camshaft. The only camshaft that sucks is the original 4.2 camshaft. There should be a 40 or 50 horsepower difference between the 4.2 and 4.0 camshaft. There should be no power difference between the “RV” Crane cam that I use and the 4.0 cam. The only advantage is that the power increases differently and peaks at a lower RPM. Crane also makes performance camshafts that will see a minor increase in horsepower, we’ll say 5 HP, at the expense of rough idle and decreased fuel efficiency. A Crane cam costs much more than a stock 4.0 cam. Considering the cost and benefit, I assumed you would stick with the stock 4.0 cam for options 4 and 5 but opt for the performance cam if you buy one for options 1, 2, 3.
1) Stay with the original 4.2 motor because it runs fine.
2) Get a long block 4.2 crate motor
3) Get a short block 4.2 crate motor
4) Get a long block 4.0 crate motor
5) Get a used 4.0 with low miles
6) Get a 4.7L Stroker crate motor
7) Build a 4.7L Stroker motor using your old engine and used parts
8 ) Install an AMC V8
1A) Stay with the original motor as is and install the Hesco MPI kit. Pay 1K to rebuild your transmission. Pay 2K for the Hesco kit and have it installed. For 3000 total you’ll have a used engine that starts and idles much better than stock. You’ll have a used engine with 125 HP for $3000.
Adding a performance camshaft gives you a used engine with 165 HP for $3250.
Adding a 4.0 head without replacing the camshaft is foolish because its less power for more money. You’d have 155 HP for $3500.
Adding a 4.0 head and performance camshaft gives you a used engine with 195 HP for $3700.
1B) Stay with the original motor as is and install Gronk’s Motorcraft 2150 carb. This is not something you or I would do because we love MPI, but it’s an important option for someone else reading this list. In comparison to option 1A, many would argue the benefit of MPI is not worth the cost. Pay 1500 dollars for transmission rebuild, the cost of the kit, and the installation. You’ll have a used engine that starts and idles much better than stock but needs annual adjustments. Most people would go this route because it literally costs half as much as the first option with negligible difference in performance. The restriction from the original intake and exhaust manifold doesn’t matter initially, but its effect diminishes the increase from head and cam upgrades. It also is a very simple upgrade that leaves most of your engine alone. It’s very easy to troubleshoot. You’ll have a used engine with 125 HP for $1500.
Adding a performance camshaft gives you a used engine with 150 HP for $1750.
Adding a 4.0 head only gives you a used engine with 140 HP for $2000.
Adding a 4.0 head and performance camshaft gives you a used engine with 180 HP for $2200.
Rebuilding your lower end similar to option 1C but with a 2150 carb would give you a nearly new engine with 180 HP for $2900.
1C) Have your mechanic rebuild your engine with new main bearings, rings, rod bearings, gaskets, seals, and timing chain. This is easier than rebuilding a transmission. I expect that he would charge you between $700 and $1000 including all the parts. A short block crate motor with this work already done would cost $1200 to $1400 dollars but it would include machine work to make it slightly more reliable. This is also a good option if you can find a low mileage motor below 60K miles for less than 300 dollars to have rebuilt and ready to install before dismantling your roadworthy car.
This option means that you’ll have a nearly new engine with 195 HP for $4500.
2A) You could take the mechanic up on his original offer and get a long block crate engine installed. If you left it totally original it would cost you 3000 dollars for a brand new engine with 115 HP.
2B) You could add a Hesco MPI kit to the long block 4.2L. 1K transmission rebuild, $2000 to 2200 for the crate motor, and 2K for the MPI kit. It will cost you $5000 for a brand new engine that gets 125 HP.
2C) You could be foolish and buy a long block 4.2L instead of a short block crate motor. This costs 2000 to 2200 dollars. Afterwards you could buy a new head gasket, camshaft, and head to replace the brand new camshaft and head the long block came with. That will cost you $700 dollars. You’ll still get the Hesco MPI for 2K. You’ll have spent $5700 for a brand new engine that gets 195 HP.
3) Get a short block 4.2L crate motor and add a Hesco MPI for 2K. This costs between 1200 and 1400 dollars. Add $700 for a new 4.0 head and performance camshaft. Install engine and rebuild transmission for 1k. You’ll have spent the same as option 2B but gotten much more power. You’ll have created the identical engine as option 2C for cheaper. You’ll have spent $4900 for a brand new engine that gets 195 HP.
4) You could start with a 4.0 long block crate motor before adding MPI and installation costs. You will have a new engine with 190 HP for $5000.
In comparison to option 3 you will have spent a meager 100 dollars more for a meager 5 HP less. The minor decrease in power is the result of the slightly smaller displacement and negligible difference between stock 4.0 and performance camshafts. The advantage is that you may protect your crate motor warranty if you do not disassemble the engine. It will take slightly less time to install. Your engine will be equivalent to a stock 1992 Cherokee instead of a hodge-podge of different parts. You will have the metal timing gear already. You will have the bolt bosses on the block to accept 4.0 accessory brackets with ease, which makes it much simpler to install a superior serpentine belt system.
5) You could get a low mileage used 4.0 along with all the serpentine belt accessories, computer, and wiring harness for about $600 dollars. You would not need most of the Hesco kit but still need a crank position sensor (Hesco’s notched harmonic balancer kit), speed sensor, and a fuel pump ($600 total). Installation would cost 1K still, but minor issues during installation will add up to 500 dollars in labor. You will already have a respectable camshaft and head.
You will then have a used motor with 190 HP for $2700. (In comparison option 1A which gave you a used engine with 195 HP for $3700 and option 1B gave you a used engine with 180 HP for $2200)
6) A 4.7L stroker motor is available as a crate engine for about $2700. A stroker is externally the same as a 4.0 motor. It uses a larger volume of fuel and will get less fuel mileage. It gives alot more power for a relatively small amount of money. 0ption 4, in comparison, gives you a new complete 4.0 engine with warranty and 190 HP for $5000. The stroker crate motor would provide a new complete 4.7 engine with warranty and 260 HP for $5500.
A 4.9 crate engine is also advertised with three year warranty for $3700. Its advertised to provide 315 HP but I find that to be possible only if they tested it at a very high RPM. If you used it in a reasonable RPM range I bet it would provide 300 HP. That's still quite respectable. You'll need special high volume injectors and you'll lose considerable fuel mileage but gain lots of power. That gives you a new motor with 315 HP for $6700.
7) Build a 4.7L Stroker motor using your old engine and used parts. Option 5 could be modified by machining the used 4.0 block and adding your old 4.2 crank. I estimate a $1500 dollar added cost for the rebuild and machine work. You would then have a new 4.7 engine without a warranty and 260 HP for between $4500 and $5200.
I would suggest buying a different 4.2 crank to use while your Eagle remains roadworthy because the machine work and rebuild would take two to three months for your mechanic to complete (he has to wait to send parts out and get them back) and another month or two to source the parts. If your donor parts have low miles and you simply rebuild and assemble everything without machine work, you can expect it to cost $3500 to $4700 (including 1K for transmission rebuild and engine removal). This is a popular option because it compares well to the cost of the crate engine options but gets more power while all the expenses come slowly and in big chunks instead of all at once.
8 ) Install an AMC V8. This is a viable option because of Terry’s conversion mounts that he makes for $350 dollars. A donor AMC V8 in good condition with all the accessories and manifolds included costs between $400 and $900 dollars. The radiator must be upgraded ($150) and your front coil springs should be upgraded to heavier Javelin spring ($100). The rear axle should be upgraded, but I will not include the rear axle cost because a stock 4.0 is also too powerful for your stock rear. I will not include the upgrade of the transmission because a T5 works fine behind a 304 and mild 360, but it should be upgraded to a NV3550 or TF727 behind a 401. I included the 1K transmission rebuild and engine swap labor, but included an extra $200 dollars to modify the exhaust. I assumed a basic engine rebuild with new bearings and rings but no machine work at a value of $800 dollars. Since we’re comparing to the quality of fuel injected 6 cylinder, I included a 1300 dollar fuel injection kit for the V8 as well as $200 for a performance cam. An MPI kit is available for $2900 dollars but it’s much more common to install the Howell TBI kit on an AMC V8.
With a 304 V8 you’ll have a nearly new engine with 225 HP for $3500.
With a 360 V8 you’ll have a nearly new engine with 295 HP for $3600.
With a 401 V8 you’ll have a nearly new engine with 340 HP for $4000
Crate motors with warranties are available for AMC V8s. They would add between $1500 to $5000 to those cost estimates. A professionally built AMC 401 has the potential to provide well over 400 HP.
Topic: New 4.2 or new 4.0? (Read 33875 times)