P7100 operation video, need help

K

keyboard

New member
Joined
Dec 25, 2010
Messages
43
Alright theres a thread in the video section with a crappy video on p7100 operation that I made and I told you guys I would make a really good one but I ran into something that maybe you guys could help me with.

[youtube]scqNLTMBFM8[/youtube]
 
Last edited:
Guess I can only edit it so many times. I saw you helping 95ram, thanks for trying. I have tried all the ways I know as well lol. The actual video is what I need help with haha, embedding it would be nice too though. http://youtu.be/scqNLTMBFM8
 
Everything is in there how it is normally. AFC is bolted on like usual same with the fuel plate.

As for the fueling arm movement, I am going to see if I can't measure it between idle and engine off on my truck. Oil doesn't sling out of it or anything, I've watched it before. Then we'll know just how much it comes up.

Theres just a lot of weirdness because the stock plate has the weird contour which if you just floor it, the fueling arm just slides up until it hooks the first edge and then it obviously cant get past that but the fueling arm is designed to be bent so the governor can continue to press the fueling arm up. It would be different if it was actually supposed to be set higher up, but I'm not sure. I'll test and figure the thing out. Would be nice to see a completely stock truck to know where it is in stock form.
 
from what i have learned in the past is that you want the foot to start just above the bottom of the fuel plate so that you dont risk it slipping under the plate. as far as the afc foot, that should move forward out of the way once boost is made. from my assumptions on that set up is the foot is there to defuel if boost is not achieved. once boost is achieved it will move out and your fuel plate will take over to control the fuel. i might be wrong on that as i am far from being an expert on it but by your video thats what i gathered.
 
I think thats how everyone understands it but it doesn't make sense why the AFC isn't longer. I just gotta keep staring at it and playing with it.
 
what do you mean by the afc being longer? i guess that in some combination of movement the afc foot and fuel plate work together in controlling the the fuel. from what i understand on the fuel plate profiles is that the contour of it is what controls the fuel delivery through out the rpm range. if its flat it delivers the same throughout the rpm range. stepped like a stock plate cuts back fuel on the top as it sticks out farther than the bottom of the plate. the 10 plate starts with a little fuel down low and more fuel in the mid range and then cuts back on the top end.
 
You are right. In my vid you saw how the fueling arm went up and down when I pushed the governor in and out. But you also saw how the AFC arm is about 3/16" above the bottom of the fuel plate. So that means it couldn't possibly do anything if the fueling arm is calibrated to the bottom of the fuel plate. My belief is that the arm raises when the truck is running to the point that it is in front of the AFC arm, but then that would make half of the #10 plate useless since its halfway up it (has to be in order to contact the AFC) and that would make the gradual fueling not really a reality. But I am not sure, I want to test the one on my truck and see just how much it moves around.
 
the position of the afc foot will also vary depending on the spring tension, housing position, and pre boost setting. before i have had the spring so tight it wouldnt move the afc in low boost situations. which in turn would prevent fueling til boost was built. the afc foot will stay in the way and keep it defueled until desired boost is reached and move it out of the way and let the fuel plate take over.
 
I am talking vertical movement of the fueling arm.. The AFC only moves horizontal. Eh let me take a pic. You can see the arm against the plate, the AFC is ABOVE the arm, so how could the AFC push the arm back when its above it.. That's what I am talking about. As RPM goes up, the arm raises. But if we calibrate it to the very bottom of the plate then how does the bottom contour of a plate have any effect when it instantly moves up when you start the truck.. I am not 100% on this and thats what I want to measure.

28lf041.jpg
 
like i was saying boost pressure will move that foot forward. until it does your limited on fuel til it reaches that point if you fail to build boost it wont move. or if you dont build enough boost it will only defuel.
 
Chevycummins said:
like i was saying boost pressure will move that foot forward. until it does your limited on fuel til it reaches that point if you fail to build boost it wont move. or if you dont build enough boost it will only defuel.
Click to expand...

You're missing the point he is making. With the arm set to the bottom of the plate (as pictured), it is too low to actually come into contact with the plate, regardless of horizontal position.


Back to the subject. When you set the arm to the bottom of the plate, the engine is off, flyweights are retracted, arm is low. Start the engine, flyweights expand, arm rises up. I think you're right that the bottom part of the plate is never contacted in a normal running situation. I have had times in my 12v when I took off from a stop light in 2nd, rpm's dropped to about 600 and I was giving it just a little bit of throttle. I could feel the arm go under the AFC and it would hang there. Truck would smoke until the boost built up enough for the AFC to budge and the throttle would jump back. I ended up lowering the AFC a bit to get rid of that.
 
I see what he is saying. Like I said before I am assuming that is how it would work. I am no expert by no means. I was just guessing by the video he posted and what I do know about its function.
 
That is how it works. The AFC arm keeps the fueling arm from moving over and hitting the plate as a means to keep fuel rates down during low boost conditions, then boost pressure moves it over and allows the fueling arm to ride the plate. But it cannot do that if the damn fueling arm is never in front of the AFC arm. Tate gets what I'm saying.

However, Tate you say you made the AFC lower, how?
 
keyboard said:
That is how it works. The AFC arm keeps the fueling arm from moving over and hitting the plate as a means to keep fuel rates down during low boost conditions, then boost pressure moves it over and allows the fueling arm to ride the plate. But it cannot do that if the damn fueling arm is never in front of the AFC arm. Tate gets what I'm saying.

However, Tate you say you made the AFC lower, how?
Click to expand...


There is a 10mm bolt on the front of the AFC housing holding down a triangular looking thing. the foot rides on a shaft that has a bit of an offset and its connected to the triangle piece, by twisting the triangle one way or another it either raises or lowers the AFC foot.
 
Ah. I saw the offset part but didn't know how that was adjusted. Sure doesn't look like it would move it enough to get it level with the plate. I just gotta measure the lift from when the truck is off to when it is idling, thats all there is to it. I am doing other stuff to my truck so hopefully tomorrow I will get to measuring since I should have it running tonight.

Thanks for the info youngguns15
 
So you your wanting the foot lower not longer. that clears up what I thought you was asking. just watch when you adjust it so that it won't get stuck on top of it either. If it stays forward that long while coming back down
 
I would adjust the afc down and take another photo. When removing the AFC housing, and you loosen the 10mm bolt on the front of the housing, you can watch the AFC arm move up or down. It rides on an eccentric (?).
 
Well truth be told the total distance from all the way up to all the way down is a whopping 0.029". That's not even 1/32". I measured it with calipers over and over because it looked like it was moving more than that, but it isn't. Gonna go measure the fueling arm in my truck now that it's running again.
 
You must log in or register to reply here.
Back
Top