Tech Letter Of The Month
Gas Versus Diesel
Question: I have a '79 Jeep Wagoneer and an '87 Chevy K30 M1028 army truck. I want to make a multipurpose vehicle (trails, expedition, rocks, and streetable). The Wagoneer has front and rear Dana 44 axles, a Quadra-Trac transfer case, an AMC 360 engine, and a TH400 transmission. The K30 has a Dana 60 front, a 14-bolt rear, an NP208 transfer case, a TH400 automatic, and a 6.2L diesel. I want to put the two vehicles together to make a Wagoneer with a Dana 60, a 14-bolt, and an NP208. However I am unsure what engine and frame to use.
Doug
Plainfield, IL
Answer: The Dana 60 and 14-bolt axle are mighty big and heavy, but if you are running 37s or larger you'll be glad you have the big axles. The 208 is better than the Quadra-Trac since it has the centered rear output for the 14-bolt, where the Jeep case is offset, though the Jeep case can be built into a part-time case. I think you should stick with the Jeep frame. Though the Chevy will offer more suspension options, it has some issues with steering-box mounting cracks and would require both wheelbase and body-mount modifications. Although the 360 is a good engine and with some good options would probably make the truck more zippy and fun, the diesel conversion should be more fuel-efficient, but it might take a while to get the investment out of the swap and by then you may be tired of the low performance of the 6.2. The 6.2 has some infamous bottom-end weaknesses and is known for being gutless and lacking the longevity of other diesels. If it was me, I would keep the 360 and TH400, swap in the 208 or find an NP205 which doesn't require the rear slip-yoke eliminator, and then stuff the big axles under it all. However, the TH400 has a 10-spline output and the GM version you have is 32 splines, thus requiring a rebuild of the Jeep TH400 or an adapter to use the GM TH400. Meanwhile, if you want a diesel, wait until you find a cheap Cummins six-cylinder.
Diesels are especially popular these days, partly due to the fuel efficiency. But the cost of swapping in a diesel rarely is recouped in the fuel economy of the engine. Plus, not all diesels are created equal-many older versions are loud, underpowered, and heavy. Also not every gas station sells diesel, which causes more headaches. Since diesels are so heavy they can require other upgrades to frames and suspensions. If you do swap in a late-model diesel and then crank it up for more power, you'll most likely lose some of that fuel economy you initially were hunting for. I like diesels, but swapping them in is not always the most economical choice.
This is a topic that is helpful to many readers interested in diesel swaps and as such it is this month's Tech Letter of the Month. T-max Winches (877.862.8629 www.t-maxwinches.com) will be sending you a 9,000-pound Outback Series Wireless winch. This 12-volt winch is outfitted with 94 feet of cable and weighs around 80 pounds. Plus, the three-stage planetary geartrain will be exactly what you need when you're taking that Wagoneer out exploring and dip it into a muddy pit, no matter if you decide to run the gas or diesel engine.
More (Over)Drive
Question: I have a '78 Blazer with a Chevy 400 and TH350 backed up by an NP203 (converted to part-time). My axle ratio is still 3.42 running 35s. I am going to change to a taller ratio, probably 3.73. I just received a TH700R4 backed by an NP208 transfer case. Can I do a swap without having any issues with my gear ratios being affected?
Anonymous
via 4wheeloffroad.com
Answer: I think you should swap in the 700R and 208, as you will gain overdrive and a lower First gear in the transmission, and the 208 has a lower low range than the 203. Also, the 208 is much lighter than the massive 203 since you will be swapping from a chaindriven iron transfer case to a chaindriven aluminum case. The 208 has a rear slip yoke and you'll want to change this.
Tranny Adapter
Question: I was wondering if you knew of a company that makes an adapter for linking a Chevy 5.3 Vortec or 350 short-block to a Ford C4 trans.
Jon
Holland, MI
Answer: You'll need a Campbell Enterprises (www.campbellenterprises.com) GM-to-C4 Ultra Bell. You'll want the JW Ultra Bell; however, you'll need a custom torque converter with the GM front design and the C4 output.