The 282 in the 656 Hydrostatic drive uses a speed advance system. The very early gear drive 656 also used that speed advance. We only sold one 656 gear drive that had speed advance. I believe there may be a few mixed in with speed advance before all gear drive 656 were load advance. The difference is that a speed advance pump has no automatic advance at low speeds and gradually starts to advance the injection timing as the engine speed increases. It maintains that advance at all loads unless speed of engine decreases sufficiently to reduce advance. The load advance works differently and to me gives a smoother running engine under load but may rattle more under no load. The load advance gives full advance as soon as the engine is running. It maintains that full advance at low and high speeds under no load. As you come under a load it retards injection. Now, the reason they used the load advance, which by the way is what all 4 & 560's had, is that in a Roosa master pump, the end of injection is constant except for the advance. The beginning of injection takes place earlier as you come under load due to the governor opening the metering valve, giving engine more fuel. The more fuel it gets the farther out the pumping plungers are forced. That causes them to contact the cam ring earlier so it starts injecting fuel earlier in the cycle. Why IH chose to tell us this was not good, and turn around and use the speed advance is for the engineers to answer. Apparently, due to the increased rpm's the hydro runs they felt the load advance did not meet their requirements. The speed advance is normally not nearly as touchy and need as frequent adjustments as the load advance but it can cause the same symptoms if it does not advance enough. That is usually a miss at higher speeds and works fine under load. Both advances are operated by fuel pressure so if you have low fuel pressure it will not adjust up correctly. You have to put a window on pump to watch advance or have a pointer device which I guess is easier to read, never had one. Of course static timing is just as important and if automatic advance is working correctly you can play with that a little, not much though. Also, a timing light for a diesel does not work on a Roosa master system due to the constant end of injection. I live out here in western Minn and don't do much tractor work any more. . Too old.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Box Plow Blues - by Tom Schwarz. One of the first implements most tractor owners obtain is the box plow. For very little money, this piece of equipment promises to plow and flatten any hill or vale on your ranch road or farm. At least that's what I thought! As simple as a box plow appears, it can be rather challenging to make work correctly. In our sandy soils of Florida, traction is king. You can never have wide enough tires or heavy enough weights to get all the traction you want … unless you own a monster tractor. U
... [Read Article]
Latest Ad:
Oliver 550 Diesel runs like a watch three point hitch pto engine gone threw about two hundred hours ago nice clean tractor
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
