Loose ends. They make up the majority of our projects, yet rarely does any magazine article do justice to those small, albeit important, components that are necessary to get the job done.
Our Project D150 was no exception. Certainly, rebuilding the engine to produce nearly double the horsepower and torque output of the Slant Six was a reasonable task. In doing so, it was well within the power range of a small-displacement Mopar small-block. Now the goal was to take the combination off the engine stand and get it firmly between the framerails.
Follow us through the minutiae involved with getting our D150 on the road, and see if our challenges assist you in getting your project further down the road to completion. Just click on the sidebars below to get the scoop.
Fuelish Endeavors
The lifeblood of any engine is gasoline. Functionally the original system would have worked fine, however, we needed a more aesthetically pleasing arrangement that also reduced the chances of vaporlock.
The majority of the work involved reforming the fuel lines from straight stock and efficiently routing them in order to gain both function and form.
To keep the engine bay neat,...
To keep the engine bay neat, we rerouted as many lines and wires as possibleincluding new fuel linesin order to avoid going over the top of the valve cover.
A fuel filter was definitely...
A fuel filter was definitely a must, so we chose K&N's billet fuel filter. We snapped the filter onto its mounting bracket, located on the framerail.
After we completed our conventional...
After we completed our conventional fuel routing and checked for leaks, our Holley 2-bbl was ready to go.
Optima Batteries recommended...
Optima Batteries recommended a Deep cycle battery for the long hours we spend listening to CDs while working on the truck. Deep cycle batteries are more capable of constant cycling. In this photo we install one of the power leads.
Power Supply
From early on, we only considered Optima Batteries for supplying amperage. The aesthetic favorite not only looks good, but also fulfills the deep cycle needs of our D150, due to our audiophile status.
All the hoses and wires were...
All the hoses and wires were covered with Techflex wire loom. Techflex is a nylon braided covering, available in several sizes and colors. There are even Velcro versions for the hard-to-wrap, complex wire assemblies.
Detailing Details
A host of new wires to power the electric fan, signal the MSD Ignition, and route accessory cables required the use of wire loom covering. We turned to Techflex for the braided wire loom, which would give a finished look underhood.
Spark It Up
Proven ignition performance is easily accomplishable, thanks to MSD Ignition and its straightforward installation instructions, which incorporate factory components and aftermarket systems.
We installed the MSD 6AL ignition...
We installed the MSD 6AL ignition on the firewall, only to have to relocate it due to clearance problems with the windshield wiper motor. An RPM Module Selector Switch (PN 8671) was added to control engine redline.
We mounted the coil next to...
We mounted the coil next to the ignition box in order to simplify the wiring arrangement and keep leads to a desirable length.
Our factory assembly manual...
Our factory assembly manual and a test lamp assisted us in locating a 12-volt, keyed power supply for the MSD 6AL.
Cool Air
The nature of our accessory drives required simplification, as we added an aftermarket air conditioning compressor. Additionally, the opportunity to remove the water pumpmounted fan afforded us a way to remove the power-robbing effect of the cooling fan.
We lowered a Flex-A-Lite electric...
We lowered a Flex-A-Lite electric fan (Black Magic M150) in place of the original. The Flex-A-Lite fan will keep the engine cool without taking power away from the Slant Six.
The wiring is found on the...
The wiring is found on the side of the housing, which contains an adjustable themostat to activate the fan anywhere from 180 degrees F to 240 degrees F. An accessory lead also activates the fan when the air conditioner compressor is functioning.
Even Cooler
Although the Slant Six is a venerable and efficient engine, it has a reputation for being a hot runnerand were not talking performance here. In order to alleviate the typical concerns of oil and transmission cooling, we added aftermarket coolers to reduce underhood temperatures.
To help with the cooling needs...
To help with the cooling needs for the transmission and the engine, we installed Perma-Cool's Maxi-CoolTM oil cooler. Here, the brass fittings were installed so the rubber hose would adapt to the cooler.
We mounted the Maxi-Cool TM...
We mounted the Maxi-CoolTM oil cooler in place of the radiator overflow tank. Notice the three 3-1/2-inch holes we drilled through the radiator core support to accommodate airflow.
The throttle valve lever on...
The throttle valve lever on the transmission was replaced. This photo shows the old (A) and new (B) lever.
Full-Throttle
Anyone who has attempted to replace a stock carburetor with an aftermarket unit has dealt with kickdown linkage. Fortunately for Mopar enthusiasts, they have a friend in Randy Bouchillon. Bouchillons Kickdown Cable Kit makes head-scratching completely obsolete.
Because we outfitted the Slant Six with a new Hooker header and Holley carb, the original kickdown rods would no longer work. Bouchillon sent us a TorqueFlite Kickdown Cable Kit that installed so easy, were still amazed. This kit works with most 62-and-later Chrysler rear-wheel-drive vehicles fitted with a TorqueFlite transmission and just about any carburetor, including our Holley 2-bbl.
A cable bracket was bolted...
A cable bracket was bolted onto the transmission using an existing hole. We made a small, 1/2-inch indentation in the floorpan for clearance.
We ran the cable down the...
We ran the cable down the driver side of the truck frame and looped it back to the transmission. Here, we snapped the cable onto the throttle valve lever.
Bouchillon supplied the bracket...
Bouchillon supplied the bracket that mounts to the intake manifold flange using the rear carburetor studs. We mounted the bracket, then installed the throttle cable and the kickdown cable. The kickdown cable has a quick adjustment at the carburetor to adjust shift quality.
Exhausted
We took the truck to TMEC, a local exhaust shop, to have our new Gibson Cat-Back system and Random Technologys high-flow catalytic converter installed. The experts at TMEC evaluated our exhaust system and the factory layout. The final result was clearly a custom exhaust system that looked good and cleverly evacuated the exhaust sound behind the passenger-side rear wheel.
TMEC first measured and cautiously...
TMEC first measured and cautiously fit all the pieces together, making many modifications and bends before doing any welding.
Considerable work was done...
Considerable work was done to gain a perfect fit from the header flange, around the oil pan, and to the Random Technology catalytic converter.
The final touch: The Gibson...
The final touch: The Gibson chrome exhaust tip is welded coming out of the right side, behind the rear wheel.
Downright Polar
Creature comfort was definitely on order and as such, we opted for a little help from Vintage Air. We ordered a complete R134a systemwith the exception of the evaporator coil, where the original sufficed. Our kit even included all the fittings, barrier hoses, and brackets, as well as a pressure switch and expansion valve. To keep things in the engine compartment uniform and looking good, we ordered the polished compressor and chrome drier.
We opted for the universal...
We opted for the universal A/C bracket to hold the front of the compressor...
...and a small slotted bracket...
...and a small slotted bracket to secure the side of the compressor. This would allow the A/C compressor to be secured by connecting it to the power steering pump bracket.
The condenser was installed...
The condenser was installed with four brackets, one in each corner. Here, a hole is drilled through the bracket and into the radiator core support.
We had Best's Lakeland Hose...
We had Best's Lakeland Hose Service crimp all the fittings onto the hose ends. This photo shows a crimping press securing the fitting to the hose. This local service came to our door and handled the hose end installations.
Because we used the original...
Because we used the original evaporator coil, we cut the fitting off the old hoses and, as shown here, Best braised new ends to fit our hose.
Be Cool
The tanks on our original radiator were shot, and while we had made repairs previously, new leaks were now appearing. Rather than continue to repair the down-flow radiator into service, we turned to Be Cool, which built us a custom cross-flow, four-row radiator. The result was better coolant flow and lower engine-operating temperaturescertainly part of the equation for additional performance from our Slant Six.
If we had made the swap simply...
If we had made the swap simply for aesthetics, we would be applauded. The Be Cool radiator easily replaced our original factory core and routed the lower return hose away from other rotating accessories.
To further clean up the look...
To further clean up the look and offer rigid hose construction, we used Inglse's CoolFlex upper and lower radiator hoses.
The Results
To be brutally honest, we were a bit reluctant to discover the actual output of our Slant Six at Vincis Hi-Performance in Orlando, Florida. Would we meet our goal of producing V8 performance from the six-banger?
On the chassis dyno, we ended up with 140.1 corrected horsepower at the rear wheels and 194.0 lb-ft of corrected torque. According to Vincis, this equals 175 hp and 243 lb-ft of torque at the flywheela whopping increase of 85 hp and 83 lb-ft of torque as compared to a stock Slant Six.
We also widened the rpm range of power, and now the engine maintains an average of 120.5 hp and 178.1 lb-ft of torque through 5,000 rpm. And yes, it will break the tires loose!