In the Cummins inline 6 cyl diesel found in Ram Pickups, there is a mechanical fuel regulator called a Fuel Plate:
My question is, how does it work?
Is there some kind of follower that rides the profile of the plate’s slope, the way a lifter rides the profile of a cam lobe?
Are there also plates in the injector pumps of other brands of mechanical diesels, such as the inline 5 in Mercedes Benz diesels of the late70s/early 80s, VW-made 6 cyl found in Volvos, Detroit Diesel 6.2/6.5 v8s in select Chevy and GMC trucks, and Powerstroke Ford diesels…made by International Harvester?
it’s technically called a “fuel stop plate” which means it limits the maximum quantity of fuel the pump can inject. It’s so you can use the same injection pump on engines of different displacements and power levels. see, inline injection pumps work by having one plunger (piston) per cylinder, and the plungers are moved by a small camshaft. which means the plungers always move the same distance. so in order to control the quantity of fuel injected, the plungers have a helical groove cut in the side, and the cylinders they reside in have a hole (spill port) in the side. When you move the position of the accelerator pedal, what you’re controlling is the location of the spill port relative to the groove in the plungers. at low engine load, the spill port is positioned such that through most of the plunger’s travel the fuel just dumps back into the galley and isn’t pressurized until the last bit of travel where the port is closed off. As you increase demand on the engine, the spill port rotates such that more and more of the plunger’s travel is used to pressurize and inject fuel.
the fuel stop plate on these pumps simply limits the travel of the rack controlling the spill ports. People who build up these engines for power (adding bigger/more turbos) need to be able to inject more fuel, so they use different fuel stop plates.
all injection pumps have some method to limit maximum fuel quantity, but I don’t know which ones allow you to easily change it. The GM and Ford IDI engines used a distributor-style Stanadyne DB2 injection pump (except the GM turbo 6.5 which used an electronically governed DS4) which didn’t have a “plate,” but you could adjust the maximum fuel quantity by removing and access cover and turning a hex screw inside it. Not advisable unless you were adding airflow.
ETA: all Ford trucks with “Powerstroke” branded engines were electronically injected. The 7.3 and 6.0 Powerstrokes had hydraulic/electronic unit injectors (HEUI) and the 6.4 used high-pressure common rail. The new 6.7 Powerstroke (which is Ford’s own and not designed or made by International) is also common rail. The older 6.9/7.3 mechanical engines are the “IDI” engines (indirect injection, using pre-chambers.)
Isilder, diesels don’t rely on throttles to control engine speed. the engines of the era OP is referring to had no throttles/butterfly valves whatsoever.
modern diesels do have a butterfly valve in the intake, but it’s not to control the engine speed, it’s there to increase pull through the EGR system.