Colorado Red 2

Nov. 01, 2006 By ORC STAFF

In our last edition, I outlined the Colorado Red project and our basic plan of attack. I will continue to update you on the project every month since I hate to loose track of a project once it has begun as much as anyone. This month, we received the 4.7 stroker kit from HESCO Manufacturing in Birmingham, AL ((205) 251-1472) and performed machine shop work on the engine. In addition, we had Sam's Off-Road in Tulsa, OK ((918) 446-5535) build a custom Dana 44 rear axle. Colorado Red is currently with out engine, transmission, and transfer case as it awaits its new performance parts. Here are some specifics about the engine and rear axle.

The 4.7 Stroker Kit

HESCO Manufacturing in Birmingham, AL is best known for its work in the Jeep racing circuit. They build race motors for the big boys and have adapted some of the technology into a kit you can buy to make your 4.0 engine come alive. The idea here is simple; but it is the math that will get you. HESCO's kit increases the cubic displacement by increasing the stroke of the motor via the crank, rods and .060 over pistons. HESCO's unofficial slogan is "Speed Costs Money, How fast Do You Want To Go?" and so far part of that slogan is true. The kit is not cheap at $2000.00 retail. It includes the crank, cam, pistons, rings, and rods all balanced and ready to install. As for the "speed", HESCO claims 260+ hp and 350+-ft lbs. of torque can be expected from this motor when you install the recommended peripheral equipment (better keep that wallet out awhile). HESCO advised us to use 20% larger fuel injectors and an adjustable fuel pressure regulator to feed the beast. In addition, they recommended adding a bored throttle body to increase airflow. All these peripherals added up to roughly another $1000.00. Knowing it will be able to breath-in better, Steve (the Owner) also directed an upgrade to the exhaust so it will breath-out better. For this, we ordered a Borla header from Four Wheel Parts Wholesalers here in Oklahoma City ($333.00) and plan on using a free flow catalytic converter and Flowmaster muffler. I asked HESCO what they recommended for machining the head. They advised we retain the pre-1991 head design since it is not cost effective to convert to the H.O. motor head. The head should be machined and put back to factory "new" condition to retain low-end toque. "Nothing fancy" was the advice HESCO experts provided.

Folks Machine Shop in Norman, Oklahoma is considered the one of the best in the Oklahoma City area where the build-up is taking place. So, we took Colorado Red's tired (135K miles) 4.0 motor there for the machine work. Leaving nothing to chance, Folks double-checked all the HESCO parts for proper balance and all were found to be within .5 grams. They line honed the block which should allow the crank to rest easy and reworked the head before installing all new valves. The bill for the machine work was roughly $645.00. Currently, the motor parts reside with an expert mechanic who has built hundreds of Jeep 4.0 motors.

The Custom Dana 44 Rear Axle

There were many debates over which rear axle to use for Colorado Red. We discussed using a Ford 9 inch, but it would not support the ARB locker Steve wanted installed. Then we discussed a Dana 60 reverse rotation; but everyone we talked to said a reverse rotation 60's pinion/ring was about the same strength as a regular rotation Dana 44. This being the case, why carry the extra 60-75 pounds around and give up 3/4 inch in ground clearance to a Dana 44? Then we talked to the folks at Sam's off-Road in Tulsa, Oklahoma. They said a Dana 44 with high quality axles would take care of business just fine. In their showroom, they have a custom axle on display. Here, they explained many of the upgrades available. The rear disc brake set-up, which is adapted from a Ford Explorer, is particularly interesting. It is a drum and a disc all in one.

The disc is used for main braking and the drum is for the emergency brake. Sam's technicians said this set-up works very well on and off-road. The decision was made and we ordered the Dana 44 with disc brake set-up, ARB air locker, and 4.56 gears. All total, the rear axle came to roughly $2300.00. Sam's built the custom axle using a housing from a Ford truck as the foundation. It was cut down to fit the XJ, leaving off the spring pads until we install the axle. This will allow proper pinion adjustment with out the use of shims. They used high alloy axle shafts from Currie Enterprises to handle the increased torque.

We will have to wait to install the axle until we have the Atlas II transfer case installed to determine proper pinion angle. Similarly, we cannot order driveshafts until we have both components installed and measure for the appropriate length.

What's Next?

Next month, we'll take a close look at the engine assembly. We have contracted with a local engine builder to perform the assembly and no doubt he can pass along some words of wisdom for anyone who is planing to build a 4.0. In later months, we will cover the engine installation, Atlas II installation, and rear axle installation.