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Low manifold pressure (boost) fuel delivery adjustment.
A.K.A. Smoke Screw Adjustment
NOTE: this will increase the exhaust temperature by about 75 degrees F on long grades.
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This adjustment is fairly simple and will help considerably around town at low engine speeds and low boost conditions.
There is a small cap in the center of the 'fuel-control device' atop the pump (the 'appendage' that is plumbed to the intake manifold and restricts the amount of fuel injected until the manifold pressure is above atmospheric).
This cap can be readily removed with two small screwdrivers and a gentle rocking motion. Beneath the cap is a torx T-25 screw and a lock nut that holds it. The locknut is 13 mm and has a 'break-away torque' of around 100 in-lbs. Turn the T-25 screw 2 turns clockwise and tighten the locknut to 125 in-lbs. Clean the plug with CRC Brake cleaner and seal it with LocTite pipe thread sealant with teflon. Externally, it will appear stock.
- For additional fuel (and smoke) the screw may be turned farther (CW).
- Back it off (CCW) to reduce smoke.
Full load fuel delivery rate adjustment.
This adjustment will TURN UP THE POWER and smoke.
NOTE: this will raise the EGT very quickly at full throttle:
The main adjustment (effects are similar to swapping the torque plate on the P7100 pumps) is found under the AFC diaphragm that is held on with a 4-screw cover. This one.
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MARK THE POSITION OF THE DIAPHRAGM, then remove the diaphragm -- there is a stamped tick mark on it, so use a magic marker or scribe to note the position of the diaphragm vs. housing.
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Remove the diaphragm and shaft, and note the shaft is both tapered and on an eccentric.
I'm only allowed 5 pictures per post, so please click here for a picture of the eccentric/diaphragm assembly
Usually, rotating the shaft 120 degrees clockwise will cause the wear to go to the richest (smallest diameter, effectively) part of the shaft. You may want to start at 90 degrees and then go farther if that does not produce the power you want. The farther you go, the higher and faster EGT will climb. The fuel stop part rubs up and down along this shaft, and note the way to install the shaft that allows maximum travel of the fuel stop part that hits this shaft and is perpendicular to it.
Just pay attention and mark stuff so you can put it back the way it was, and you should be able to figure it out just fine. After adjusting the diaphragm eccentric, the low boost fuel rate may need to be adjusted slightly to reduce low speed smoke. (see the first adjustment, the one under the cap)
Caution: The banjo bolt that holds that air line onto the diaphragm case is very VERY fragile. No need to reef the sucker down. Just snug it up.
AFC Star Wheel Adjustment
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Fuel delivery pin is circled in RED. Starwheel is the toothed wheel in the center of the image. The retaining lock is on the right hand side of the starwheel. It is spring loaded and meshes into the teeth on the starwheel.
Under the AFC diaphragm and spring is a star wheel adjustment which sets the spring tension on the fuel load delivery rate diaphragm. If your star wheel (under the AFC spring) is set too high, the delivery rate pin won't move downward as it should with increasing boost levels.
-Turning the star wheel up (counterclockwise) increases the spring pressure, and slows the delivery rate.
I'd suggest turning the star wheel down (clockwise) in 1/4 turn increments until you smoke, then back off (counterclockwise) till smoke is gone to your satisfaction, or smoke on under power, a black haze, not a black soot cloud.
The retaining lock spring doesn't have to be removed, the star wheel will rotate with a small screwdriver gently placed and pried between the wheel and the lock spring. Note the location of the wheel, mark it, and count any turns for reference. Mark this adjustment and direction of turn down in your notebook.
Remember:
Star wheel down (clockwise) = less spring resistance = increased fuel delivery rate (more fuel)
Full Power Adjustment
On the rear of the pump, partially concealed by the fuel lines, and under a cone shaped plastic cap is an other adjustment screw. Remove the plastic cap, remove the metal collar tack-welded to the screw, loosen the jam-nut, and turn the power adjustment screw clockwise about 1 to 2 turns. Write this number down in your notebook.
After turning the Full Power Adjustment, you may need to re-adjust the Smoke Adjustment Screw to reduce low speed smoke, and the idle screw or throttle linkage to correct the idle speed.
Tip: The easiest way to remove the collar is to back the whole unit out of the pump, put it in a vise and remove it (the collar). Be careful not to turn the screw in the lock nut as you are doing this or you will lose the "known" setting of the pump. After removing the collar simply reinstall the unit and adjust accordingly.
I hope this helps. It helped me!
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Low manifold pressure (boost) fuel delivery adjustment.
A.K.A. Smoke Screw Adjustment
NOTE: this will increase the exhaust temperature by about 75 degrees F on long grades.
This adjustment is fairly simple and will help considerably around town at low engine speeds and low boost conditions.
There is a small cap in the center of the 'fuel-control device' atop the pump (the 'appendage' that is plumbed to the intake manifold and restricts the amount of fuel injected until the manifold pressure is above atmospheric).
This cap can be readily removed with two small screwdrivers and a gentle rocking motion. Beneath the cap is a torx T-25 screw and a lock nut that holds it. The locknut is 13 mm and has a 'break-away torque' of around 100 in-lbs. Turn the T-25 screw 2 turns clockwise and tighten the locknut to 125 in-lbs. Clean the plug with CRC Brake cleaner and seal it with LocTite pipe thread sealant with teflon. Externally, it will appear stock.
- For additional fuel (and smoke) the screw may be turned farther (CW).
- Back it off (CCW) to reduce smoke.
Full load fuel delivery rate adjustment.
This adjustment will TURN UP THE POWER and smoke.
NOTE: this will raise the EGT very quickly at full throttle:
The main adjustment (effects are similar to swapping the torque plate on the P7100 pumps) is found under the AFC diaphragm that is held on with a 4-screw cover. This one.
MARK THE POSITION OF THE DIAPHRAGM, then remove the diaphragm -- there is a stamped tick mark on it, so use a magic marker or scribe to note the position of the diaphragm vs. housing.
Remove the diaphragm and shaft, and note the shaft is both tapered and on an eccentric.
I'm only allowed 5 pictures per post, so please click here for a picture of the eccentric/diaphragm assembly
Usually, rotating the shaft 120 degrees clockwise will cause the wear to go to the richest (smallest diameter, effectively) part of the shaft. You may want to start at 90 degrees and then go farther if that does not produce the power you want. The farther you go, the higher and faster EGT will climb. The fuel stop part rubs up and down along this shaft, and note the way to install the shaft that allows maximum travel of the fuel stop part that hits this shaft and is perpendicular to it.
Just pay attention and mark stuff so you can put it back the way it was, and you should be able to figure it out just fine. After adjusting the diaphragm eccentric, the low boost fuel rate may need to be adjusted slightly to reduce low speed smoke. (see the first adjustment, the one under the cap)
Caution: The banjo bolt that holds that air line onto the diaphragm case is very VERY fragile. No need to reef the sucker down. Just snug it up.
AFC Star Wheel Adjustment
Fuel delivery pin is circled in RED. Starwheel is the toothed wheel in the center of the image. The retaining lock is on the right hand side of the starwheel. It is spring loaded and meshes into the teeth on the starwheel.
Under the AFC diaphragm and spring is a star wheel adjustment which sets the spring tension on the fuel load delivery rate diaphragm. If your star wheel (under the AFC spring) is set too high, the delivery rate pin won't move downward as it should with increasing boost levels.
-Turning the star wheel up (counterclockwise) increases the spring pressure, and slows the delivery rate.
I'd suggest turning the star wheel down (clockwise) in 1/4 turn increments until you smoke, then back off (counterclockwise) till smoke is gone to your satisfaction, or smoke on under power, a black haze, not a black soot cloud.
The retaining lock spring doesn't have to be removed, the star wheel will rotate with a small screwdriver gently placed and pried between the wheel and the lock spring. Note the location of the wheel, mark it, and count any turns for reference. Mark this adjustment and direction of turn down in your notebook.
Remember:
Star wheel down (clockwise) = less spring resistance = increased fuel delivery rate (more fuel)
Full Power Adjustment
On the rear of the pump, partially concealed by the fuel lines, and under a cone shaped plastic cap is an other adjustment screw. Remove the plastic cap, remove the metal collar tack-welded to the screw, loosen the jam-nut, and turn the power adjustment screw clockwise about 1 to 2 turns. Write this number down in your notebook.
After turning the Full Power Adjustment, you may need to re-adjust the Smoke Adjustment Screw to reduce low speed smoke, and the idle screw or throttle linkage to correct the idle speed.
Tip: The easiest way to remove the collar is to back the whole unit out of the pump, put it in a vise and remove it (the collar). Be careful not to turn the screw in the lock nut as you are doing this or you will lose the "known" setting of the pump. After removing the collar simply reinstall the unit and adjust accordingly.
I hope this helps. It helped me!
