Home   Forums   Gallery   Vendors   Advertising   Links
Go Back   DieselRam.com > Diesel Ram Technical Topics > Technical Info: 2nd Gen 12 VALVE DRIVETRAIN
Technical Info: 2nd Gen 12 VALVE DRIVETRAIN Technical discussion of second generation (1994 - 1998) 12-valve engine and drivetrain questions, solutions and upgrades.
Reply
 
Thread Tools Search this Thread
  #1  
Old 05-02-2007
kbbt's Avatar
kbbt kbbt is offline
Senior Member
 
Join Date: Feb 2006
Location: vegas
Posts: 1,188
Default afc mods (lots of pics)

I thought I would do a write up on modifying the afc for more rack travel and a smoother fuel curve.
There are a few things you can change/modify easily that limit rack travel (fueling) in the pump via afc. One is the cup washer on the side of the diaphragm near the spring. Another is the shaft part of the afc foot that slides on the round shaft. Next is the smoke screw, this determines pre boost fueling. Last is the starwheel, this determines how fast the fueling comes in according to boost.

First thing to do is to remove the afc from the injection pump.
Next remove 4 screws (1 is a break off screw) to get to the afc diaphragm.
afc diaphragm.

Next remove 10mm nut holding diaphragm on.

Once the diaphragm is off remove the cupped washer on the spring side and replace it with a flat automotive body washer with the same outside diameter and 8mm hole.

Now that part is done, put diaphragm back in and cover back on.
Next modifying the afc foot.
Remove 10mm bolt holding the slide shaft in.

Take a flathead screwdriver and pry out slide shaft.

Remove shaft and afc foot.

Now grind 1/16" to 1/8" off the round part of afc foot that slides on the shaft.

Now that part is done reassemble afc foot and shaft.
That's it for the rack travel mods.
Next is the smoke screw. The smoke screw is located behind a small cover on the diaphragm cover. Remove 2 screws (one break off) pull off cover.

This controls the 0 boost fueling, the further in the screw the more tension it puts on the afc spring, allowing more fuel to come on with no boost.
Smoke screw on inside of cover.

To adjust smoke screw loosen lock nut 10mm, use 3mm allen wrench to adjust smoke screw in or out.
Smoke screw all the way out.

This adjustment can be done at any time, on or off the injection pump.
Last is the starwheel.
Remove plug located on top of afc using 8mm allen wrench.

The best way to adjust the starwheel for proper fueling is to use regulated air. Use an air blow gun with a rubber tip, set pressure on compressor to the psi you want full fuel. I'll use 40 psi as an example.
Insert blow gun into the afc where the boost line comes in.

Adjust starwheel until afc foot travels completely forward with 40 psi of air. The more tension thats on the spring the more psi needed to move the foot forward. Too much tension on the spring will cause the spring to bind up and the foot will not move all the way forward.
With the starwheel adjusted for full fueling at 40 psi the afc foot should barely touch the front of the housing.

At 20 psi the foot should move about half way forward.

And this is with no boost.

Install starwheel plug back on afc.
Now that the afc is complete install on injection pump, adjust afc housing forward or back according to you're tastes.
The smoke screw can also be adjusted at this time too. Just remember to put the small cover back over the smoke screw when the fueling is to your liking.
__________________
코리찰튼
98 12v qc 2500 4x4 dtt valve-body self built auto 4.10 S&B Intake, Steed Speed manifold, gauges, 100hp Maxsticks, tweaked & tuned 911 pump,18*,custom ground plate,4" exhaust,htb2 62/14, pdr cam ,arp studs, 3k gsk


sʇıpǝɹɔ uoqɹɐɔ ʎɯ ʎnq ɐuuɐʍ
Reply With Quote
  #2  
Old 05-02-2007
ACC1079 ACC1079 is offline
Senior Member
 
Join Date: Nov 2004
Location: Cleveland, TN
Posts: 458
Default Re: afc mods (lots of pics)

Excellent write up with great pictures. Appreciate the time and effort. Hopefully a admin will see this and put it in the how to section.
__________________
95/RC/DRW.O-ringed Head,SS Valve Seats,HX35/BHT3B Twins,Pump Massaged by Jeff Garmon,20* Timing,DDP3's,191DV's,FASS 180gpm@45psi,4kGSK,60# Springs,Banks Twinram,Fluidamper,ATS Pulse Manifold,ARP Studs,Georend Trans -w- Triple TC,Billet Flex Plate,Lots of Powdercoating,To many other bells and whistles.
http://i15.photobucket.com/albums/a3...Nov09_0003.jpg
Reply With Quote
  #3  
Old 05-02-2007
gkainz's Avatar
gkainz gkainz is offline
Senior Member
 
Join Date: Sep 2006
Location: Arvada, CO
Posts: 4,509
Default Re: afc mods (lots of pics)

Nicely done!
What does replacing the cup washer with a flat washer do?

Admins - this one needs to go into the HowTo section - with Brownie points! (or maybe a free t-shirt?)
__________________
Greg
97 2500 4x4 ExtCab LB Auto; Isspro gauges (pyro, boost, tranny); 75hp Maxsticks, MaxTrans auto, KDP killed; BD DSS; 3rd gen 17" wheels; GM 1ton rear brake cylinders; Westin step bars; Extang tonneau cover (snaps and cold SUCK!). Pakbrake exhaust brake, TS Performance TC Lockup.
coming soon: fuel plate (sitting in the box waiting to install), AFC mod, 3K GSK; coming someday: exhaust, turbo (somebody say "evil twins"?)
Reply With Quote
  #4  
Old 05-02-2007
MAXTORQ's Avatar
MAXTORQ MAXTORQ is offline
Administrator
 
Join Date: Jan 2004
Location: GOLDEN ,COLORADO
Posts: 18,971
Send a message via Yahoo to MAXTORQ Send a message via Skype™ to MAXTORQ
Default Re: afc mods (lots of pics)

Done, very nice job indeed. [img]/forum/images/%%GRAEMLIN_URL%%/cool.gif[/img]
__________________


www.maxtorqdiesel.com
Reply With Quote
  #5  
Old 05-02-2007
csutton7 csutton7 is offline
Member
 
Join Date: Apr 2007
Location: SF,CA
Posts: 48
Default Re: afc mods (lots of pics)

very nice write up--congrats----chris
__________________
'99 4x4 741 hp--thanks to Bullydog, PDR, J&H, Winspeed and Nowel Thomas(RIP)
Reply With Quote
  #6  
Old 05-02-2007
Joe G. Joe G. is offline
Senior Member
 
Join Date: Dec 2003
Location: Eureka, CA
Posts: 1,589
Default Re: afc mods (lots of pics)

Very nice. Good pictures. One small nit pick. I think the smoke screw should be adjusted so that it barely touches the diaphragm so you know where you are before adjusting it on the engine. Also keep notes when you are adjusting the smoke screw and star wheel on the engine so you can keep track of where the adjustments are.
__________________
Joe George

'95 2500 CC auto 4X4,3.54,Combo EGT/boost guage,trans temp guage,custom switch panel,PacBrake,TST #5,Piers 370s, DTT TC/VB,motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit
Reply With Quote
  #7  
Old 05-02-2007
truxster truxster is offline
Senior Member
 
Join Date: Nov 2006
Location: Sacramento
Posts: 280
Default Re: afc mods (lots of pics)

Joe, i didn't think it was possible but i think you have outdone yourself with this write up. Great job!! Now i have weekend project.
__________________
95 Ram 3500 Reg.Cab, 2WD, Banks Turbine hous. with Big Head wastegate, BHAF, Autometer trans,pyro,boost, #8 FuelPlate, 4"Exh, 47RH built w/the best
Reply With Quote
  #8  
Old 05-02-2007
Joe G. Joe G. is offline
Senior Member
 
Join Date: Dec 2003
Location: Eureka, CA
Posts: 1,589
Default Re: afc mods (lots of pics)

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: truxster</div><div class="ubbcode-body">Joe, i didn't think it was possible but i think you have outdone yourself with this write up. Great job!! Now i have weekend project.</div></div>

Not my doing. I only added one nit pick comment to the good job by kbbt.
__________________
Joe George

'95 2500 CC auto 4X4,3.54,Combo EGT/boost guage,trans temp guage,custom switch panel,PacBrake,TST #5,Piers 370s, DTT TC/VB,motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit
Reply With Quote
  #9  
Old 05-02-2007
truxster truxster is offline
Senior Member
 
Join Date: Nov 2006
Location: Sacramento
Posts: 280
Default Re: afc mods (lots of pics)

SORRY KBBT!! I accidently congradulated the wrong person, Good tech. write up and pictures. Joe G. your still a big help.
__________________
95 Ram 3500 Reg.Cab, 2WD, Banks Turbine hous. with Big Head wastegate, BHAF, Autometer trans,pyro,boost, #8 FuelPlate, 4"Exh, 47RH built w/the best
Reply With Quote
  #10  
Old 05-02-2007
truxster truxster is offline
Senior Member
 
Join Date: Nov 2006
Location: Sacramento
Posts: 280
Default Re: afc mods (lots of pics)

Kbbt, i realize changing the cup washer with a flat 8mm washer will increase the rack travel, but what exactly will i accomplish by additional rack travel; (Maybe smoother/predictable throttle response?) and what would i accomplish by sliding the whole afc housing forward. Thanks Jeff
__________________
95 Ram 3500 Reg.Cab, 2WD, Banks Turbine hous. with Big Head wastegate, BHAF, Autometer trans,pyro,boost, #8 FuelPlate, 4"Exh, 47RH built w/the best
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 04:22 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2015 www.dieselram.com. All material found on this site is property of DieselRam.com.Ad Management plugin by RedTyger