JBradley500

I've been curious about adding length to the fuel pin (the small one, not the cone) to get better control of my AFC. Yesterday i took my pump-top off to document at which point the fuel cone is deep enough that the AFC-Pin/AFC-Lever max out.

I did this by putting paint on the fuel cone. I installed it and lowered it into the bore while at the same time moving the AFC-Pin/AFC-Lever. This gave me a mark in the paint showing where the pin loses contact because the lever hits the pump internally. (I believe the small pin can get "shot" out and make a mark on the deeper part of your fuel cone and you think it is taking advantage of the deep cut but the actual AFC-Lever isn't moving any more.)

Here's a picture of the fuel cone with the mark in the paint.


Here's a picture of a diagram I drew with dimensions. This shows locations of the deepest part of the fuel cone's cut and where the AFC-Pin loses contact.


I guess what i'm getting at is.... a lot less of the fuel cone ramp is actually functioning than i thought. Of course different ramp's on different aftermarket cones will vary. The best way to get more movement out of the AFC-Lever would be to add a longer AFC-Pin but theres only enough room to add 1/32" to it before the lever hits the pump (on the opposite side from before). You could machine some material from the pump so the lever will move back more but theres just not enough material there to remove.


Disclaimer- If i rambled and any of this doesn't make sense just let me know and ill try to make it clearer.

B-North

Your pics are broken.

JBradley500

Are they working now? I reached my bandwidth limit on photobucket and had to upload them from facebook.

Richie O

i see them

B-North

yup fixed

feveree40

very interesting. i see what you are saying. I have heard of people shaving down the lever to gain movement, but not the housing so much.

JBradley500

yeah the lever to go forward, i would machine the housing to go backwards if there was more material and i knew that it would work.

93flatbed

I'm lost. You want to the pin to retract more into the housing so the cone can come up further? For less fuel at low/no boost. Or am I way off kilter here?

JBradley500

I have the cone coming all of the way up... but i want the small pin to push the lever back farther (if possible) to have even less no boost fuel... keep smoke down and such.

I knew that the fuel cone wasnt being totally used but i had no idea it was only using that first "17/64 inch" of the denny t pin.

No real good point, just showing what numbers id found and maybe some guys with more experience would have something to say about it.

93flatbed

Ok gotcha. Could you "tweak/bend" the arm to acheive what you are after?

I've been thinking of putting a "boost elbo" in my afc line to help out what you trying to fix. So it will only see half boost or so. But from what I have read the pin is at full travle around 20ish psi. And I have no problem hitting 40 so it may work?

JBradley500

no you cant... its a c-channel shape lever.

i have a shut off valve in my afc line and shut it off most of the time. i think i have read that 10psi of boost collapsed the afc spring? i think unixcowboy did some testing with it.

jimbo486

I've also heard of 10psi being all it takes to compress the AFC spring. As far as that goes, I was considering calling the fuel injection shop near me and inquiring about stiffer springs if any are available.

JBradley500

it doesnt seem like it would be hard to get what you want... you get an OD measurement, height, compressed height and the stiffness you want... then call a spring place and see if they can make what youre looking for.

jimbo486

Isn't that what unixcowboy was doing some R&D on? I thought I read that he was making a stiffer one.

JBradley500

yeah hes got his own spring... he might be around with pics i bet