Muscle Mustangs & Fast Fords
The Four-Valve Swap Power Struggle Upgrade Part 2
Our Quest For Reliable 9-Second Timeslips From Our Modular Powerplant Continues.
The only other hood-clearance problem we experienced was with the alternator bracket. One of the bolts that secures the hoodscoop came down exactly on top of it. We cut off the unused length of that bolt, and the stock hood happily closed over the new powerplant--Bullittness maintained.
Connecting The Dots
Wiring was next on the agenda. The Two- and Four-Valve motors are remarkably similar in their components, however, they vary slightly with regard to the placement and location of certain items. You can attack this variance in one of two ways. Either use the Two-Valve harness and extend the wiring on the connectors that require extension, or use a Four-Valve harness as we did. After comparing the wiring diagrams on both the Mach 1 and Bullitt, it looked like the new Mach 1 harness was pretty close to plug and play. But it wasn't as close as we thought, as we discovered later when we started the car and found it ran on significantly less than eight cylinders. Ford wiring diagrams are not as user friendly as we hoped.
Watson used his extensive
instrumentation trouble-shooting background to start tracing from the EEC plug to the plug in the engine compartment to see where the electrons were running amok. Changes were required at the firewall interconnect plug. When installing the Mach 1 harness, we didn't use its transmission connector since we already installed a separate harness for the transmission during the previous 4R70W automatic upgrade. We later discovered four of the coil-pack wires were routed through the unused Mach transmission connector. Those four wires were cut and reconnected to the correct wires on the firewall connector.
Even with these variances, it's our consensus the Four-Valve harness is the way to go if you have that option. Wire lengths are correct and routed properly, and all the right plugs are attached. It looks OEM when you're finished. Stealth and the original stock look is something we are attempting to maintain, even with the massive changes in this original Bullitt Mustang.
It also should be noted the car already had a Mach 1 Automatic computer installed. This was done when the 4R70W was installed in the car, so no changes were necessitated there. Although the GT/Bullitt Two-Valve computer could be used to control a Four-Valve, we suggest you upgrade to a Four-Valve EEC--the main difference being the speed of the processor. With the ability of the Four-Valve motor to turn significantly higher RPM, the faster Four-Valve processor provides some headroom to run all of the background loops and properly controls the motor.
Next up was the fuel system, which necessitated the death of some gray matter as we pondered how to feed and control the huge 95-lb/hr Acceleronics injectors. Pulling pump gas out of the sumped stock tank is a Barry Grant King Sumo fuel pump, which feeds a -10 braided-steel line that runs up to the engine compartment. This is where things get tricky.
The fuel rails supplied by Fore Precision Works are a work of art, but we were unable to do a rear inlet/front outlet flow pattern with them due to clearance problems with the coolant crossover tube on the front of the motor. There was just no way to attach a -8 line there, even with a 90-degree fitting. This, of course, wouldn't be a problem with the intended normal non-return system.
After much discussion, we decided to feed the rear of the rails with a T-fitting and allow the front end of the rails to deadhead. The -10 feed line comes into the engine compartment and splits into a pair of -8 lines. Each of these runs through a T-fitting that is screwed into the back end of each rail. After the fuel passes through the T-fitting, the supply lines then join at a Y junction before coming to a relative stop at the fuel pressure regulator. It's this holdup that pushes the fuel into the rails upstream.