firewalker

need som advice on increasing fuel to ip. i took afc cover off yesterday to find fuel screw. i saw a rubber cap covering what i thought was fuel screw. i did see ametal collar that surrounded what lookeed to be a plastic button(shirt) with apin hole in center .is their a screw in this little hole, or am i in the wrong spot.the collar is bent like some one has had pliers on it to squeeze it. can anybody enlighten me on this? TIA.all help is appreciated.

G1625S

of the screws you can see in the pic below (the ones with the provision for a flathead screwdriver) the one on the upper left is the high-idle stop. The one on the upper right is the low-idle stop or just plain 'idle screw'. The lower left-ish, also the larger of the three, is the full fuel screw. This is really the beginning and the end for significant power gains from the VE...all the other adjustments are simply available to compliment the setting of the full fuel screw...IMO, of course Thanks to Jim Lane for having some VERY detailed pics of the VE in his gallery

edit: this view of the pump is as if you are standing on the brake booster looking toward the radiator.

firewalker

thanks. i was in the wrong location.great pic., very informative

G1625S

No problem! And don't forget to look here: https://www.dieseltruckresource.com/...d.php?t=102027 for more detailed info on pump tweekage.

xtremexj

The fuel screw is the one on the lower right or the big one in the center? I'm confused.

G1625S

look more closely and you'l see that there are only three actual screws in the picture...you can tell because they have a slot for a flat blade screwdriver. Of the three with the slot, the lowest one is the full fuel screw. The hole in the center is where the overflow valve threads in.

xtremexj

Thanks for the clarification.

Ace

And NOT a good place to attach a fuel pressure gauge!

G1625S

I won't even ask

wannadiesel

https://www.dieseltruckresource.com/...d.php?t=110530

Sorry, Ace - but you brought it up.

firewalker

hey guys , i turned fuel up today as far as collar would let me.i am impressed with the results i think i only made 1 turn but no more than 2.truck seems to fast for that od tranny.once it shifts in to od it screams .ran between 95 and 100 before tweaking,but now the sucker is quick and that is what i was looking for .still have that muffler and 2.5 exhaust,its 3 inches down to muffler.does anybody think i should go 3 straight back without muffler. also have no gauges,do ya think i really need em. truck is my everyday driver so its not gonna be for play. just wanted the extra oomph for pulling 30 ft . camper.do like that quiet exhaust though.just wanted to say thanks to everybody for their insight and wisdom.their is abbundance of knowledge on this site,good to se it being shared. thanks again

BearKiller

When the Cummins genius, that helped me with my engine swap, doctored my fuel screw, he handed me a rubber 0-ring and a copper-colored washer, that came out from under that tin thimble-looking cap that he removed to get at this stuff.

He told me to hang on to the washer and 0-ring, in case we had to put them back in.

I haven't seen reference, anywhere else, to this washer and 0-ring.

One thing for sure, it definitely woke up my truck.

If I ignore the pyrometer, nobody can touch me on a long hill.

firewalker

i didnt see a washer and o ring either.did pretty much trash that thimble though

wannadiesel

Yes, you need a pyrometer - especially if you will be towing.

If you are towing and like it quiet, why would you even consider straight-piping the truck?

You ought to put a trans temp gauge on for towing as well as the pyrometer. A boost gauge is nice, but it is not vital.

firewalker

figured the bigger exhaust would help with egt,and wanted to know if 2.5 would make egt ,much higher than the 3.do prefer it quieter though.