clarification on the altitude valve
 

In doing a static timing check on the d24t, does the altitude valve on the side of the pump when 12v applied increase the advance by much?. So should i set it to .95 then apply 12v cont while running as I live at sea level. Would that increase fuel economy even better.

Works the opposite of the way you think it does. The design logic has the altitude compensator solenoid 12V energized at low altitudes, and de-energized at high altitudes (above 3,000 ft.)

Easy to test: With engine running at low altitudes pull off the solenoid wire and listen for (or feel for) the click. You may or may not perceive a difference in idle speed or sound.

The de-energized solenoid theoretically advances timing ~0.07mm.

Really a backwards way to achieve the compensation, as it is not failsafe-friendly. IOW, if the circuitry or wiring fails, that creates a normally overly advanced timing condition, potentially damaging the engine over time.

Setting injection timing for best fuel economy is not that straightforward for high mileage examples. Internal IP parts wear and can reduce IP internal dynamic advance range and action. One can compensate by advancing static timing only so far.

In my own experience, my own examples run well with good economy at .95mm static timing. With altitude compensator functioning as designed. And of course set while the cold start solenoid cable is temporarily disengaged.

To clarify, static timing is set while the engine is off. Therefore the altitude solenoid would be de-energized.

For a fun visual that illustrates the explanation above, here is a video from some years ago when a pump I had rebuilt by a diesel shop was getting run on the Bosch calibration test bench. The tech was generous enough to let me watch and bother him with questions. It shows the effect of that advance solenoid when the pump is actually operating (and also the effect of the cold start advance lever).

https://www.youtube.com/watch?v=-adERDGFPaI

The pump really screams when it's running at governed RPM. :cool:

According to that tech, the ~0.07mm (in terms of pump plunger travel) advance provided by de-energizing that solenoid equated to about 1 degree of actual injection timing advance as measured by his equipment, and more like a degree and a half when he cranked it up to near max pump RPM. It is unclear if he meant crankshaft degrees or pump degrees (which would each be 2 degrees at the crank). And it is interesting to wonder if this result would be different on different injection pumps with various amounts of internal wear, drifted calibrations etc. It probably all comes down to how much preload is set on the advance piston spring with the shims down there but the performance of a new or freshly refurbished/calibrated pump like the one that was being tested there, vs one that had some miles on it, maybe would be different. And perhaps different at different fuel temperatures/viscosities, with different fuel types (diesel/biodiesel/blend), different RPM, etc....