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July 2011 Techline

Flat Tappet Cam
Willie Worthy | Writer
Posted July 1, 2011

Your Tech Questions Answered!

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

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