1979 Ford® Conversion Build

The original frame the 7.3L Powerstroke was in is fairly wide. You realize this about the time you try to set the engine in a ’79 F250. The factory engine mounts on the 7.3L stick out, so  we at Diesel Conversion Specialists make a set of engine side mounts that hug close to the block. These mounts allow the most room possible when trying to get the engine between frame rails. Once between the rails, frame side perches were made for the puck style isolators to rest on. The 7.3L is a bit bigger than the old 351, so a cross member was incorporated with the isolator perches. This helped to take some of the twisting stress load off the frame. Front factory cross member on the ’79 will need to be notched or cut out for oil pan clearance. For this build the old cross member was cut out, and a new cross member fabricated allowing for the clearance needed.

Once the cross member was cleared the Differential to oil pan clearance was going to be an issue. A 4” lift from Rough Country gave the distance needed to clear the oil pan. The large oil filter of the 7.3L is still pretty close to the differential. It is advised to install a remote oil filter before taking it off roading.

While test fitting the engine it was obvious the power steering pump and the gear box were going to hit. Some builders have used a GM® gear box on these older Fords. Diesel Conversion Specialist makes an accessory drive power steering upgrade and relocation mount. This mount is set up to use a Ford power steering pump out of a 6.4L Powerstroke and gives you the clearance needed to keep the factory gear box. The new pump also made it easy to swap out the old vacuum brake booster for an updated Super Duty® hydra-boost system. Wow, do the brakes work now!

For the charge air system, a Mishimoto intercooler was placed in front of the radiator. These old trucks were not skimpy on room under the hood. So, fitting a charge air cooler between the radiator and grill is feasible with a little bit of fabrication. Diesel conversion Specialists sells intercooler pipes to be fitted for this setup.

Exhaust routing was achieved by using the factory 3” downpipe then transitions to 4” after clearing the bell housing. Muffler down stream keeps the neighbors happy and a 5” chrome tailpipe ends the system.

The Midship fuel tank was removed and a single large rear tank was installed. Feeding the engine with a steady stream of fuel is the FASS titanium series pump purchased at dieselconversion.com.

For the transmission it was decided to go with the automatic 4R100 that would have been mated to the 7.3L. By going that route, we were able to use the 7.3L PCM to control the transmission. All we had to do was make some shift point adjustments that better suited the application via HP Tuner software and DCS tuning. The factory ’79 cross member and mounts for the C-6 transmission were removed and a new cross member was fabricated to support the 4R100 and factory isolator. Shifting linkage was done by adapting the ’79 linkage to the 4R100 gear selector arm. The fluid coupler between the engine and transmission is a triple disk low stall torque converter from Diesel Performance Converters, and the torque converter can be purchased at dieselconversion.com.

The transfer case that was selected for this build is BW4406. I know, I know, why would you take out the NP205, you should have stayed in bed that day. Well, the NP205 mated to the 4R100 is a great package, minus the distance between the gear selector and the front driveshaft. It does work but it is tight. The NV271 that mated to the 4R100’s of this era was also a great selection. However, that case would require clocking down or cutting the frame to use. The BW4406 wound up being the baby bears porridge to this Goldilocks setup. It just clears the frame while allowing an adequate distance from the gear selector.

Dana 60 differential in the rear with a shortened driveshaft. Dana 44 in the front with a new longer driveshaft. The gear ratio of the differentials is 3.54 and with an overdrive of .71, highway speeds are achieved like never before in this olds truck.

In order to see how fast you are going accurately a new Dakota Digital cluster was installed. This cluster pulls the RPM, speed signal, and gear selection right from the OBDII port. The oil pressure and coolant temperature are taken from the engine with supplied sensors from Dakota Digital. Other inputs like fuel level, high beam indicator, and turn signals are displayed via factory wiring. All factory wiring was replaced with on American Autowire wiring system. Diesel Conversion Specialists makes a stand-alone wiring harness that adapts from the 7.3L engine harness to the PCM and IDM. Using this harness will allow you to run the 7.3L in whatever application your creative fabrication fantasies can muster up.