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November 2010 Nuts & Bolts

Scout Driver Side Mud Ditch
Fred Williams
| Brand Manager, Petersen’s 4Wheel & Off Road
Posted November 1, 2010

Jeep CJ-5 and Wrangler TJ Engine Swap Questions and More!

My First Jeep
Q I recently bought a '67 CJ-5 with a six-cylinder motor and a three-speed trans (for 700 bucks). I bought a new fuel pump and battery to get it started, but it runs rough. I don't know if the carb needs a cleaning or the motor needs a rebuild. When idling it misses, but once I rev it up it runs smoother but not perfect. I have a friend trying to tell me to pull it and put in a modern V-8, but that is costly and I don't plan on driving it that much to make it worth it. This is my first Jeep, and I don't know what I should do. What is your suggestion on making my Jeep drivable on the flat prairie and not an "over-the-top rockcrawler," as my buddy wants me to make it?
North Dakota Nick

A If this is your first 4x4 I'd suggest you fix the stock engine rather than swap in a late-model V-8. The V-8 swap is cool and will definitely give you more power, but more power will find the weak links in the rest of your drivetrain. Find a good service manual, buy some tools, and go through the steps of tuning up the old Jeep.

I had a '64 CJ-5 as one of my first Jeeps, and it was a great Jeep to learn on. The engine only needs fuel, spark, and air, so just follow those three leads. Is the carburetor leaking? Is the gas old? What kind of condition are the spark plugs, wires, and distributor cap in? Is the timing off? Does the fuel filter need cleaning? You can get that old Jeep running for much less money than tearing into it and swapping in a different engine.

Hi, Low & Reverse We Go
Q I have a question about high-pinion versus low-pinion in the front axle. I was recently attempting to pull out another truck with my '69 IH Scout 800A. It has Scout II Dana 44s, which are low-pinion front and rear. I hooked the towstrap to the front bumper, and some of the other spectators were expressing how hard that is on the gears in the diffs when pulling in reverse. I want to know which is the best way to pull with my low-pinion differentials and how they compare to high-pinions. Is there any truth to what these guys are saying? Is it best to pull in reverse with a low-pinion front? If I had a high-pinion front and a low-pinion rear, would it be best to pull from the rear? My International is pretty heavy on the front and gets great traction pulling in reverse, but am I damaging my gearset?
Myles K.
MooseJaw, Saskatchewan, Canada

A Yes, a low-pinion axle is usually stronger when driving towards the pinion, and a high-pinion axle is usually stronger when driven away from the pinion. As such, a low-pinion rear and a high-pinion front are strongest when the truck is driving forward. This is because the gear teeth have a drive side and a coast side, and the drive side is stronger than the coast side. When driven toward the pinion the low-pinion axle is on the drive side of the gear. Conversely, when driven away from the pinion the high-pinion axle is on the drive side of the gear. Some say that driving on the coast side of the gear can reduce strength by nearly 25 percent. When you have low-pinion axles front and rear, such as in your Scout, then either direction will have your truck running on the weak side of the gear in one of your axles. Though your reverse gear is usually very strong and low, I'd probably recommend pulling from the rear bumper if at all possible, as most trucks are designed to pull from that direction when towing.

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