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Discussion Starter · #1 ·
Ok, I have adjusted the star wheel a little here and there and have noticed mpg go up and down and my smoke levels increase and decrease. I have read some of the post on this topic but everyone has their own opinions on what is the correct way to do this... I would like to know THE absolute proper way to get power and mpgs from this tweak? I believe in doing things the correct way and not just "rigging" things!
 

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Tune out the off the line smoke, and keep interstate boost under 7 psi. Make the starwheel loose as you can within those two constraints.

While we're on the subject of the correct way - you should fill out your signature.
 

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Discussion Starter · #3 ·
AFC stuff

So I think that I got my signature taken care of...??? Do you think that all o the articles about grinding off part of the arc foot and all of that is all just "rigging" things together?
 

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No. 1/8th inch ground off the barrel, not the foot, is a step closer for full rack travel.

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So I think that I got my signature taken care of...??? Do you think that all o the articles about grinding off part of the arc foot and all of that is all just "rigging" things together?
No modding the afc is completely fine. The afc is where the magic happens, you can change injectors and turbos and such all you want, but you're not gonna get near their potential out of them without the afc. Grind the barrel, the part of the foot that slides on the shaft. And swap out the two lipped washers for flat ones, or just grind them flat. This will give more rack travel and thus more fuel. Now as far as tuning, the beginners section has a pretty good right up on how to do it, just follow that.
 

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Read the beginners thread along with this thread:
http://www.cumminsforum.com/forum/9.../312241-afc-tuning-explained.html#post3293034

There is a ton of very useful information in both of those. Modding the afc by grinding the barrel, exchanging flat washers, and swapping out the AFC spring is definitely not rigging anything together. Those are valuable modifications to improve the performance and tunability of the pump, which makes the truck a lot more fun to drive. I can't seem to find the write up I used, but I started by trying to tune out as much smoke as possible using the preboost screw. You want to try to find the point where you have as little smoke as possible while still maintaining the fastest spool up possible. The starwheel is all personal preference. Or the psi that you allow full fueling varies a lot from truck to truck. I have mine set up a little tight to allow full fueling at about 25 psi. I have the turbo wastegated to 35 psi. But running that AFC a little tight really cut down on smoke during normal daily driving. I am also running 5x.012's with a #10 plate on a stock HX35. So controlling smoke is becoming quite the game. Tuning takes a lot of time to see what works best. The position of the AFC housing and fuel plate and fuel plate profile also play important roles in tuning. There's a massive amount of info out there on this subject so read up!
 

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A needle valve on the afc line works wonders too. It'll delay the boost getting in to move the foot, but not limit the total pressure. So you actually have more boost in the engine before fuel. I changed out my afc spring for one that just barely allows for full travel at 40psi, and then fine tuned with the needle valve. Runs smoke free now until about 30psi boost then it starts to smoke pretty heavy.
 
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