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Discussion Starter #1 (Edited)
Aneroid boost head compensator control (AFC or Air Fuel Control)

The picture is from the Bosch VE manual, I believe there is a link to it on this site somewhere.

The boost compensator ensures the amount of injection fuel is in proportion to the air within the engine cylinder for combustion of the fuel and is then increased with the hp of the engine. When the engine is running, pressurized air from the turbo passes through the connecting tube from the engine air manifold to the boost compensator chamber (AFC pump top). Inside the chamber is a diaphragm which is connected to a pushrod (eccentric cone also known as "fuel pin") which is in turn coupled to the pin. Movement of the diaphragm is opposed by a spring, for any movement at the pin the air pressure on the the diaphragm must be higher than spring tension. When the engine RPM and load increase and air pressures in the connecting tube become high enough to overcome the tension of the spring, the diaphragm and pushrod are pushed down. The tapered "eccentric cone or fuel pin" causes the compensator pin to move in as the taper lowers and narrows, forcing the fuel control rack toward an increased fuel position. The boost compenstor reacts to the engine inlet air pressure regardless of the governor. When turbo boost reaches maximum the quantity of fuel injected will be equal to the stroke of the aneroid boost compensator pin, in additon to the normal full load injection amount that is determined by the governor full load stop bolt.

Fuel Pins with a more aggressive taper can be bought ($125 and up) or as many people have done, they can be ground DIY style, if you ruin one or want to grind one yourself they are approx. $100 new from an authorized Bosch shop. Search any of the popular diesel forums for additional Info. I would recommend checking the FAQ sections or Tech sections for additional info on the Bosch VE Fuel Injection Pump
 

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Excellent post.

I saw on a VW TDI forum a cunning mod.
The owner had only ground one side of the pin for more aggressive fueling, the other side had either a tiny taper or was completely flat.

By taking out the pin and rotating it 180deg, he could easily change his engine from max power mode, to max economy.
Of course a 1/4 turn tap on the air line feeding the aneroid would have a similar, though less tunable, result.
 

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Discussion Starter #3
Well I can't take 100% credit for that info, the late Bob Coe aka Bushwakr or PastorBob as he was known online had provided excellent write up's on the TDR and DTR. He has a great compilation on the VE, Gov' Spring and a good description of defueling, not too mention countless other tech/info there. That is my version of his description from the TDR.
 

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Discussion Starter #4
The OEM pin's tapered portion of the pin is off center slightly. If you remove the AFC part of the pump top (4 screws) you can lift out the diaphragm/pin assy and see where the pin was riding, there will be a witness mark. From all I have read it is usually about 90* off from the deepest point. Another small performance gain for nothing. But, there could be EGT issues with this fuel increase, I had my pump turned up with the fuel pin at the OEM setting and couldn't get into the red zone on the pyro but after I rotated the fuel pin it get's there. That is while driving like I stole it of course...
 

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Discussion Starter #5
Excellent post.

Of course a 1/4 turn tap on the air line feeding the aneroid would have a similar, though less tunable, result.
This idea is similar to a "valet switch", where you can switch off the aneroid boost control thus making the truck less powerfull for that particular teenage someone you don't want tearing up your prize truck...
 

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Don't forget the plastic washer under the spring mod. There are other washer thicknesses listed in the Bosch VE pump parts list; I'm sure for the different CPL versions of the engine. When this washer is thinned down you run the compensator pin closer to the center of the fueling pin at max boost and get more fuel.
 

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Discussion Starter #7
Here is a quote from Mike aka Old Smoky;

"It will add 40hp at the rear wheels, while adding throttle response, and controlling smoke. It comes with a new washer, and installation instructions. The price has been reduced to $124. I usually ship priority mail, which is $4.04."
 

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Discussion Starter #9 (Edited)
I would private message "Old Smoky" on the Diesel Truck Resource, request information and price of the Fuel Pin.

http://www.dieseltruckresource.com/dev/memberlist.php?do=getall

Use the search feature to find Old Smoky, there is another member with a different spelling there as well, I did not find the guy with the fuel pins in the actual member list but did find him with the search feature. Correct spelling is Old Smoky.
 
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