AFC position

madmikeismad

madmikeismad

So mad
After all the threads on tuning it, I'm left wondering how far back you can leave the AFC and still not have the foot limit max fuel.

Another way to explain..... If you have a mack plug, and grinded AFC foot for max travel, how far back can the AFC be and still allow full rack travel.

There we go, I think I explained my problem there well enough.
 
The idea is to gain enough movement in the aneroid that it will to not limit rack travel at any position.
 
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Yeah, but I was thinking that if the AFC pushed all the way BACK, even with mods to give the AFC arm full travel, that it might still limit rack travel. I know it won't full forward, but what about full rearward? Or is it not an issue?
 
Mine doesn't limit rack travel in any position. Forward or back.
 
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Ok, gotcha. Thanks.

What exactly have you done for AFC travel mods? How do you measure actual rack travel to see if it's being stopped by the AFC?
 
madmikeismad said:
Ok, gotcha. Thanks.

What exactly have you done for AFC travel mods? How do you measure actual rack travel to see if it's being stopped by the AFC?
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easiest way is with the pump out and the rack plug out. thats with the afc on the pump.

take the afc, put it in a vise, use shop air to cycle it and measure how much the foot moves. that will give you an idea of how much travel the afc is capable of
 
madmikeismad said:
Ok, gotcha. Thanks.

What exactly have you done for AFC travel mods? How do you measure actual rack travel to see if it's being stopped by the AFC?
Click to expand...

The usual stuff, a little cutting, grinding and milling. I use an AFC Jig.

AFCJig001.jpg


AFCJig002.jpg


AFCJig004.jpg
 
all the afc threads i read. most of them say slide it forward. now this one is slid back??? whats the difference???
 
Sabbath5.9 said:
all the afc threads i read. most of them say slide it forward. now this one is slid back??? whats the difference???
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Thats what I'm getting at. I want to leave the AFC slid as far back as possible to lower pre-boost smoke, but I don't want to take a chance on limiting rack travel. Even with all AFC travel mods done.
 
My afc is slid all the way forward. The smoke screw is turned all the way in. ( when I turn it out, the truck has no power at all) and from reading threads. The screw isn't even suppose to do anything but smoke supposely. So either my setup is weird. Or the screw does more then we think. But to me in theory. With the housing slid back. It should allow the travel be the same if not more.
 
My AFC slid full forward dumps way to much fuel in way to soon. Set halfway is where I like it. I've been wondering the same thing as you though madmike.
 
Sabbath5.9 said:
all the afc threads i read. most of them say slide it forward. now this one is slid back??? whats the difference???
Click to expand...

sliding it forward or back acts like the pre boost screw, just changes the relationship of the afc foot to the gov arm

if you do move the afc somewhere in the middle, mark the afc and the pump witha scratch or something so if you have to take it off you can put it back in the exact spot
 
The amount of pre boost fuel difference between full forward and all the way back is just crazy on my truck. Full forward makes it a pig, all the way back is the only way my truck is driveable.
 
Its still completely stock, haven't modified it yet. AFC has been off, so it might not be in stock location, but I just need to know if location matters when talking about full travel of the rack.
 
What I was getting at is if you correctly modify your AFC, it will not limit rack travel in any position, forwards or backwards. You can put it in any position you like. The AFC jig allows you to tune your AFC off the truck, you can set the foot height, see what pressure the arm begins to move, and what pressure it stops at, how far it moves, when the gov arm will hit the fuel plate, ext. It is useful for tuning, and modifying the AFC.
 
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