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Nuts & Bolts: Budget CJ Build

Posted in How To: Tech Qa on December 19, 2018
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I’m looking for some direction before I dive into a project. I’m 60 years old and have owned a 1984 CJ-7 in the past. I put a 2 1/2-inch lift and 33-inch BFGoodrich All-Terrains on it. But I didn’t do much with it and ended up selling it. I have owned three Jeep Grand Cherokees, two with V-8s, and the one I own now has the I-6. No power, but clean and low mileage. I found Dirt Every Day and am now seriously considering building another Jeep. Craigslist in Denver has plenty of CJ-5s, CJ-7s, and Wranglers for sale. There is a 1982 CJ-7 for cheap that looks OK; it is complete but sitting in a field. Rust appears fairly minimal. I want power and the ability to handle tough stuff if I get into it, but mostly the mountains of Colorado and Southern Utah, plus Moab of course.

I’m financially in great shape; kids are grown and business is doing well. But I still want to build a budget Jeep. Can you make any suggestions as to the minimum cost it takes to drop a different engine in place of the straight-six? Which suspension upgrades are needed to really have some fun and be able to handle most situations? Not extreme, but most things in Colorado and Utah. Also, I would like to tow behind a truck or Suburban and want to avoid a trailer if possible.
Dan G.
Via nuts@4wor.com

You bring up some good questions and lots of things to ponder. Even though CJ-7s were built during AMC’s darkest days, we have a soft spot for them and understand your gravitating towards one for a trail rig (though we wouldn’t pass up the right deal on a YJ or TJ). Once commonplace, now CJs turn heads on the trail among the sea of JKs and TJs. They have their quirks, but they’re still well supported by the aftermarket and can easily be built to handle your desired uses.

The biggest things to watch out for in a CJ-7 are rust and frame cracks, as the vehicles are very susceptible to both. Rust issues will be readily apparent, but frame issues typically only show up on CJs that have been used hard. As with most platforms, we prefer going with a more unmolested example so things like cutup wheel openings, frame damage, and undesirable or outdated modifications won’t be a problem. The 1976-1980 models have the possibility of factory V-8 power, while the 1982-1986 models have more desirable wide-track axles. That said, we’d consider any good example of any CJ-7.

While we understand that your 4.0L-powered Grand Cherokee is a gutless turd, don’t count out the 258 inline-six in a CJ. We find them perfectly adequate and even peppy with the right gearing and a few other simple mods, while swapping in a higher-powered 4.0L is nearly a bolt-in and nets fuel injection. If you’re dead-set on V-8 power and don’t find a decent CJ equipped with a 304 already, then a small-block Chevy or Ford will slide right in via readily available mounts and adapters. You can choose to keep the transmission that’s in the Jeep and adapt it to the engine, but do your research on the transmission you end up with; CJ-7 transmissions vary from excellent to terrible depending on the year and options. Conversely, you could use the transmission mated with the donor engine, but Bowtie and Blue Oval manual transmission options will be limited. The transfer case will be either a Dana 20 or Dana 300 depending on the year, but there were also less desirable QuadraTrac full-time cases. Both Dana transfer cases are excellent with all kinds of goodies and upgrades available in the aftermarket, but note that flat-towing for long distances is not recommended with the Dana 300. Steer clear of the QuadraTrac system unless the Jeep is a killer deal.

Overall cost for an engine swap is really impossible to gauge because there are so many variables. You can spend anywhere from $300 for a junkyard engine to $10,000 for a rowdy professionally built powerhouse. Figure anywhere from $500 to $2,000 if a transmission is part of the mix. Adapters to either a transmission or transfer case average around $500-$700, but there are some combinations (such as mating an AX15 to a Dana 300) that can be very inexpensive. Ford people hate admitting it, but swapping Chevy stuff is usually cheaper because it’s more common and therefore more plentiful.

There would be very little reason to swap in a small-block and not include fuel injection with all of the factory and aftermarket injection options available. Your intended wheeling spots include a lot of steep hills and elevation change, both of which carburetors don’t like. Injection also offers better overall drivability, easier cold starts, and much more. Fuel injection can be anywhere from $200 from a pieced-together junkyard system to $2,000 for a plug-and-play aftermarket system that will bolt to the intake manifold of your choice.

All of that extra power and torque is going to be hard on everything downstream, so you’re going to want to plan on axle improvements as well. The AMC 20 has a somewhat undeserved bad reputation, but adding one-piece axles and trussing the housing nets an axle with strength equal to or greater than a Dana 44. The Dana 30 front is marginal with V-8 power, so at minimum plan on a good set of chromoly axleshafts, and don’t be surprised if you find yourself contemplating a Dana 44 swap down the road.

As for other modifications, you’ll want a good quality name-brand 2 1/2- to 4-inch lift kit. Upgrade the steering linkage with DOM tubing, and add a steering box brace while you’re at it. We’d strongly recommend some rock sliders, good front and rear bumpers, a winch, and driver-selectable lockers since you might see some Colorado snow. Put all of these things together and you’ll have a very capable rig that can handle most of the trails that Colorado and Utah have to offer for much less than the cost of a stock JK.

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