Tonite me and my friend were adjusting the stock plate on my 98 cummmins 12 valve. When we took the Afc cover off and on the front of it there is a little bolt with a ajustment underneath it. Thats swings towards the engine or towards the driver side fender. We also saw that it rides on a little cam and moves the arm on the cover up and down. Can anybody tell my what this does?

 

That is what holds the shaft for the AFC in. If you take the bolt out you can pull the shaft that your AFC foot rides on out. You do this if you are going to "gut" the AFC (remove the foot). I don't know why they make it look adjustable, mine had a washer welded to the underside of that tab so that the bolt will only go in one place.

 

it is there to line the arm up. you dont wount to move it. it is like a cam, the shaft is off set on it so they can move it around to line it up.

 

so there is really no benefit to it. Its just you line the arm up inside.
If I take that bolt and shaft out and remove the arm, as they call it "gutting it" this will give lots of black smoke, more acceleration and bad fuel mileage right?

 

Maybe! With a stock plate it won't be much. removing the AFC (aneroid) foot means your fuel is not regulated by boost pressure.

With proper tuning an AFC is your friend

 

Gutting it will make lots of black smoke if you step on it. I don't know that it necessarily makes more acceleration though. I think it can be too much. I had mine like that for a day and didn't like it so I put it back.

I say leave the AFC together and just tune it.

 

I gutted it the other night and it made alot of black smoke it felt like it had a little more acceleration. I put it back the way I had it, I have the stock plate all the way forward and the afc and I have the starwheel forward also.
I get a little black smoke of the start but for the most part it makes a nice haze and it feels really strong.

 

What and how do u swap the washers on the diaphram? Have read that this gives u more rack travel. What does this help if any?

 

Oops Hope Sig Is There Now

 

It seems people get different results playing around with the AFC. When I moved mine all the way forward I got some smoke off idle, noticably more power, and another 600 or so rpm and somewhat reduced fuel economy. Others seem to have little or no effect dinging around with their AFC.