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July 2011 Techline

Posted in How To: Tech Qa on July 1, 2011 Comment (0)
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July 2011 Techline

Cam Sources for Jeep Dauntless V-6
I have a ’70 Jeep that I am restoring and need to rebuild the engine, which I have been told is a Buick V-6. The camshaft is in pretty bad condition and needs to be replaced. I have found aftermarket performance cams, but I would really like to have a stock camshaft. However, I can’t seem to find one. Do you have any clue as to where one could find a stock unit?
Mark Williams
Salt Lake City, UT

Not a problem. Give the people at Camcraft Cams a shout (828/681-5183, www.camcraftcams.com); they offer stock as well as performance profiles for just about any engine you can come up with.

Be sure to read the article on their website on the causes of camshaft failure. What they say is very true, especially about the fact that certain high-pressure lubricant additives are no longer used in motor oil because they are not needed with roller lifters that are now used and can damage catalytic converters. There are now quite a few companies that offer additives or specialty oils that are compatible with flat-tappet, non-roller lifter camshafts.

You might also want to take the time to read what Marlan Davis has to say about camshafts and oiling in his excellent article at www.oldgmctrucks.com.

Replacement Springs and Manifold for Ford Highboy
I have a ’74 Ford F-250 Highboy with a 390ci motor on which I would like to upgrade the leaf springs and the exhaust manifolds. Every aftermarket source that I’ve looked up only have “non-Highboy” applications listed. What is the difference in the front springs? (I know the back has a lift block.) I’m not looking for a lift (maybe a little); I just need something that is not 36 years old.

The exhaust is cracked and the motor is not original to the truck, so I’m not sure what the manifold is from; it appears to be 2.5 inches in diameter. I’m not sure if headers will fit on a four-wheel drive.
Erick Dimock
Woodstock, CT

The earlier 4x4 trucks used a different-style frame and springs to give them the height advantage they have. Contact L&L Products (www.landlproducts.com), as they should have headers to fit your truck. Also try Stan’s Headers (www.stans-headers.com). Both of these companies’ products are not cheap but are very high-quality and, most likely, will outlast your truck. Another choice would be Hedman Hedders (www.hedman.com). As to stock manifolds, try Stevens Specialty Engine Parts (800/443-2673, www.stevensparts.com); they offer replacement manifolds for a wide variety of engines, including your Ford truck.

For the springs, you have a couple of options. Get out your Yellow Pages look under “Spring Rebuilders.” Yep, there are such places listed that usually do springs on commercial trucks. No luck? Then visit your local truck repair shop and ask them about who rebuilds springs in your area. Another way to go would be to contact companies like Alcan Spring (www.alcanspring.com) or Deaver Spring (www.deaverspring.com) and have a custom set built.

Diesel Military Blazer: Cummins Swap or Not?
I have an ’85 M1009 Chevy ex-military Blazer. I’m planning on some upgrades and was hoping you could answer some questions for me. I have already acquired a 14-bolt rear axle with 4.56:1 gears and a Detroit Locker, and a Dana 60 front axle, also with 4.56 gears, from a donor M1008 ex-military pickup. I intend to put a selectable locker in the front axle. I’m going to go with the high crossover steering and hydraulic assist.

My questions are in regards to the engine, suspension, and tire and wheel setup. My Blazer has the underpowered 6.2L diesel. I’m considering swapping in a Cummins and wanted your opinion on the feasibility of this swap, keeping in mind that I’d like to stay with an automatic transmission and still get the best reasonable fuel mileage. My plans also include 37-inch tires and a 6-inch lift. Will the 4.56:1 gears work well with the 37s and the diesel engine? Also, can I run 37x13.50s, or do I have to go with 37x12.50s to avoid frame or body contact on full turn or full stuff? What rim width and offset would be best? This truck is my daily driver and will be used 90 percent on the road, but I’d also like it to be capable of handling a trip to Moab and other tough off-roading trips. I’ve been getting many conflicting opinions on the Internet and would really appreciate your input.
William Mutnansky
Via fourwheeler.com

The Cummins swap is feasible. Performance Automotive (www.transmissioncenter.com) should be able to set you up with the proper adapter so you can retain your present transmission. However, if you plan on doing a lot of highway driving, then a transmission with an overdrive may be a better choice. You might just be better off buying an engine that has the overdrive automatic along with a transfer case attached.

It’s going to be a lot of work to make everything fit, especially the intercooler if you go with a turbocharged motor. It’s also going to be expensive. Going to a non-turbo’ed engine may not gain you anything performance-wise. It will not be an inexpensive swap, and you’re taking your chances on finding a good motor. The BT6 engine is noisy, and that means it’s tiring on a long drive unless you plan on lots of floor and underhood insulation.

Yes, looking at websites and forums gets really confusing, as there are lots of different people expressing their opinions, and sometimes they may or may not be providing good information. It takes a bit of effort to weed out the good from the bad.

Before you commit to the Cummins swap you have a couple of other possibilities to think about. One is to keep your present 6.2L and take off all the military 12/24-volt crap and rewire the truck. Gale Banks (www.bankspower.com) makes a turbocharger kit for this engine that makes a real difference in performance. There’s an article on this that you can check out www.fourwheeler.com for more information. It would also be a good idea to take a look at www.thedieselpage.com; it has lots of great info.

Another thought is to forget about the diesel and go with a big-block Chevy (gas) motor. The initial cost will be a lot lower, and power output would be about the same as the diesel swap. Yes, you will not get the fuel mileage, but the swap will be so much simpler. It takes a lot of miles, usually in the range of at least 100,000, to make up the difference in fuel mileage versus overall cost. Remember, oil changes in the diesel will be about double the cost, if not more, of changing the gas motor’s oil, and even fuel filters need to be changed more often and are considerably more expensive. Then there’s fuel cost. Right now in my area, diesel is almost 50 cents more per gallon than gasoline.

As to the 4.56:1 axle ratio, I think that it would be just about perfect for overall performance, both on and off the highway.

Tire clearance at full steering lock? I don’t think that the extra inch of width is a problem. A lot depends on the amount of backspacing the wheel has. You might give the guys at Off Road Design a call (970/945 7777, www.offroaddesign.com) and get their opinion on the proper amount of backspacing for clearance without the tires extending too far out the fenders. While you’re at it, look at their website for information on lift and crossover steering.

Where To Write
Address your correspondence to: Four Wheeler, 831 S. Douglas St., El Segundo, CA 90245. All letters become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department can also be reached through the website at www.fourwheeler.com. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

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