|
MSG, I am not forgetting that the original pump, on the 3010 and 4010, was a load advance pump. I think you are forgetting the basics of how the D series pump works. If you had said that the pump has no mechanical or hydro-mechanical advance, you would have been right. If you had stopped to think before you tried to make me look like a dunce, you may, or may not have known, why and how the load advance pump, advances, and retards the timing during various loads and speeds. MSG should know this, but if anybody wants a fuzzy idea of how it works, I will try to explain. First you have to know a little about how the pump works, and is designed. There is a vane type transfer pump that sits on top of the head of the pump, and the rotor that turns in the head, and drives the transfer pump. The bottom of the rotor has two opposed bores that the pumping plungers/pistons ride in. They have shoes and rollers to follow the lobes of the cam ring that they ride in. The lobes in the cam ring are opposed, so that as the rotor turns in the cam ring, both pumping plungers are shoved in at the same time. This forces fuel up through the center of the rotor shaft,through the delivery valve, and is routed to the injectors. By the way , there is about 90 millionths of an inch clearance between the plunger bores and the plungers. Now for how the timing is advanced and retarded in the load advance pump. The two things to keep in mind, the fuel is inlet metered to the pumping plungers, and the ramps in the cam ring, are basically tapered up to the high point of the lobes. At slow idle, the throttle position and governor linkage tell the metering valve we only need a very small amount of fuel. The metering valve allows the small amount of fuel, at transfer pump pressure, to the inlet side of the pumping plungers forcing them out a very small amount. As the rotor and rollers approach the ramps on the cam ring lobes, the pumping plungers are not out far enough to make contact with the ramps until near the top of the lobe. This delivers a small amount of fuel, for slow idle, at the retarded timing. When the throttle is pulled down, and under a load, the governor tells the metering valve we need all we can get. The metering valves opens, and allows the the plungers to fully charge. This shoves the plungers out until the leaf spring catches them. As the rollers approach the cam ring lobes, the plungers are out far enough to make contact with the beginning of the ramp, and start injection at the advanced timing. This is why they called them load advance pumps. The speed advance pump works the same way, only it has the hydraulic piston to rotate the cam ring some to gain a better advance retard range. While we are nit picking each other, the 4010 didn't use pintle injectors. They used a valve body with a heavy needle valve, and a tip with holes. With his description of his problem, I will give you one hundred to one odds, that lack of enough timing advance is his problem. That is what the speed advance change over took care of when every thing was almost new. They just didn't get it quiet right, or allow for 45 years of wear. You were right about the original load advance pump setting at 14 degrees, it was the 3010 that set at 10 degrees. It has been over 40 years since we were working on this problem. I forgot. You knew all of that. You were just in too big of a hurry to show me I didn't know what I was talking about.
|
