ANYTHING FOR YOU, BUD!!!!!!!!!!!
I have always wondered about doing that. I understand about them being collecters items, and if they are that easy to make then I wont have much trouble. Could you give us a little insight to what the button actually does. Thanks Tony.
The “button” (i.e. regulator plunger) acts as a pressure plunger, or regulator, just like the ones in an oil pump or fuel pump or whatever. The dif is the way it works. A Cummins PT (pressure timed) pump relies on increasing pressure to feed more fuel at a faster rate to the injectors. The more fuel, the faster the “pop” time of the injector. When the fuel cavity is full in the injector, the cam will pop it at a given rate according to when it’s “full” of fuel. The higher the rail (fuel) pressure, the faster it fills, the faster it will “pop” and unload during the cam stroke cycle on the injector lobe. At idle you may have 3 to 8psi rail pressure, hence a very slow pop (almost slobber), hence it only idles at as close to 19*BTDC as possible. Full load you will have 165 to 210psi (stock depending on CPL) with much more available with tinkering. More rpm’s, more fuel, fills much faster, pops much earlier from cam stroke to unload the injector at somewhere around 26.5 to 31* (in theory).
The plunger, as stated earlier, in a pressure plunger with a barely rounded head. The bigger the number of the button, the bigger the recess hole in the plunger. The bigger the recess, the faster and easier it can be pushed in to hold the rail to the desired steady state of pressure. On the flip side, the smaller the recess, the more pressure the pump has to build to push the plunger back against the idle spring, thereby by-passing it back into the main cavity of the T-pump inlet to start over again.
Not sure if that all made since, but in essence, the smaller the recess orifice, the higher the rail pressure by compensation. The bigger the recess, the easier to unload, hence the lower rail pressure.
All this has worked efficiently enough to make them go
for 50 years or so, but the variables in the original design are the cause of the quirks they've had since genesis, the main one being that PT pumps are RPM sensitive, not load sensitive. That means on a PT at 1/4 throttle you can hit 2200rpm, so PTO capability is close to non-existant. On a scroll or sleeve metered pump they are load sensitive, so 1/4 throttle is always 1100rpm(+/-), and if a PTO is added, it fuels more by servo and/or bellcrank to keep it there (which is obviously prefered).
Hope that helped. Be cool bro!!…T