DDP makes two governor spring kits for the p-pump: a 3000-4000 kit and a much stouter Comp 5000 kit. While the 3/4K kit would be more than enough for, say the 400-450 hp range, we knew we would eventually be taking this truck farther so we went ahead and installed their 5K kit. When removing the factory springs, pay attention to how many clicks the retainer takes before it's removed. This will help dial in the new springs when it goes together. The factory setup uses four total springs per side while DDP's kit replaces those with just two, which are much stronger than the factory equipment. When the governor springs are reinstalled, be sure both sets of springs are adjusted to the same tension, according to the clicks on the retainer. If the springs are tightened too far you'll experience a major jump in your rpms when it's revved. Too loose and it will make for a slow rev up. Just be sure to tension both sets of springs the same.
Next come the delivery valves. These will require a special tool you can get from your local tool guy. It's specific for the Bosch P-Pump delivery valve application. DDP's new delivery valves will increase pump output by another 50ccs. More injection pump flow means more fuel and more fuel means more power. Swapping these out is pretty straightforward, just be sure to lube the new o-rings when reinstalling to prevent tearing them.
Finally on our list of pump mods is the actual AFC cover and star wheel adjustments. For most, Reed says placing the AFC cover right in the center will get you the closest to dialed-in setup. Adjustment of the AFC star wheel can then be made to fine tune smoke and throttle response. The star wheel is found under the small plug on the top of the AFC housing. Rotating the wheel towards the motor loosens preload and increases low-end smoke, while rotating the wheel away from the motor will increase spring load, decreasing low-end smoke. In the end, this adjustment really comes down to personal preference.
With these modifications made, all parts that most could accomplish in a few hours we've actually doubled total pump output. DDP says the combination of these parts will increase flow by more than 200cc of fuel-not bad considering the stock unit produces just 180cc.