Got bored with the power on the 93 350, so I went to adjust the star wheel. It goes down almost 1/4 turn then is bottomed out. Is this a concern or normal? I still have no smoke and max egts are 1150, havent towed yet though. The pin is on the richest setting, and been for a while. Im still pretty sure it was virgin until my pokin around with it. The tin cap is still on the full pwr screw. Im Still paranoid to up it though after the last one.
Also I seem to remember reading something reguarding AFC spring colors which desigenated the rate. Mine here is kinda light blue color. any input on this?

 

The starwheel being that close to the bottom is not too common... at least not in my opinion. It's likely been adjusted.
The cap on the smoke screw can come on and off fairly easily so you won't really know for sure if it's been tweaked.
Your temps tell me that you have some room for more fuel but you need to do some testing with a load on the truck first.
1150*F empty is ok, but I'll bet it's more when loaded down.

As for spring colors... the light blue/light green spring is a bit stiffer than the all silver colored one.
Not alot, but a bit. This will result in the boost pressure needing to be higher/lower to start the AFC diaphram to deflect downward.
So for example, no matter were the starwheel is set, the silver spring will need less boost pressure applied to start it's downward movement and in turn begin to release low/no boost fuel earlier and faster.

Did I get that right ???

Pastor Bob....

 

That is not quite right. The silver spring is softer: it has a lower spring constant. That means that it will deflect farther for a given force applied to it. However, the star wheel sets the pre-load applied to the AFC spring. Assuming that both springs were set to the same pre-load (in terms of force NOT length of compression) the AFC would start to add additional fuel at the same boost pressure. However, the silver spring would add more fuel more quickly as boost pressure passed the point that overcame the pre-load setting of the spring.

I think that pretty much all trucks after 91.5 with stock pumps have that blue/green spring (I think that some of the trucks that got re-man pumps on re-call may have the silver spring).

Only having a 1/4 turn for the star wheel seems odd -- with the star wheel down all the way, how much does the uncompressed spring extend above the housing?

 

Can't help witht eh spring colors other than say mine has the green one. My starwheel was also about a 1/3 turn from the bottom. It is now bottomed out. I'm suprised you can get 1150 empty with just a few pump tweaks. With PW injectors and minimal pump tweaks, best I could get was 950 at 22# boost. That was with a 3 1/2" exhaust from the muffler back. The fact you are higher suggest that you still have the stock tailpipe over the axle? This is a horrible restriction spot. Just reach up there and feel. The pipe is crimped to about 1/2 it's original diameter.

Carl

 

As far as the AFC spring I cant remember how high it was above, but with the cover on and ready to bolt it back together there is 1/8 or so I think of gap. Reguarding the exhaust, when I just started in it was all original and noticed a crushed area above the axle so I wacked off the tail pipe to see if there was a difference, I didnt see any. Then I decided to replace the tailpipe out back again, dont want fumes in camper, I decided to also put a straight thru type muff on it. They installed a Magnaflo 3" x24". I question the straight thru design I asked for because I see an offset in inlet to outlet. This shop does a lot of hipo stuff and has been around for a while and I have dealt with them before, But?.
So this am I towed my stock trailer in to work for some weight, 3500 or so. flat still at 800 or so and pulling the backside of the grade I locked out o/d and didnt get past 1000 on EGTs at 55 or so. I imagine this is from more RPMs and boost and more air cooling. Kinda surprised it did this well. The real test will be going home up the 4 mile 7% grade.

 

Magnaflow mufflers are pretty good -- I wouldn't complain, even though they aren't truly "straight through" -- they have big baffles and chambers inside, like a transmission-line acoustic speaker.

A .125" gap like you describe on the AFC will let the AFC pin start moving at about 2-3 lbs of boost. That is where I have mine set. If I floor it at low speeds, I get a little smoke -- once I get up to about 7 lbs of boost, no smoke. I'm pretty happy with that.

However, to get to that setting, I am not bottomed on the star wheel . . . manufacturing tolerances, I guess. You are sure that the threads aren't just corroded or something?

 

I looked/checked several times, and backed it out then back in. I took a measurement for the heck of it from the cast base to the top of the wheel with the end of a micrometer and had .375". Then went down the 1/3 or so left. You sound like your smoke is about the same as mine. Im tempted to open up the one on my 250 that has a fresh rebuild and mike thinks out, except if it goes, the warranty will be void, the`ll be able to tell I was inside

 

So here is the result of my drive home, besides one trailer tire shredding and no lug wrench, thanks whoever stole it, Floored, 1050 EGTs 18 psi boost, down to 47 mph, 7% grade 3 miles long or so, O/D locked out, no visible smoke. Dang my old chevy 4x4 almost did as well and it was rated at 150 hp when it was new, heck it even smoked more, Trans temp ran at 215 max. Time for the full power screw and timing? there both stock,the timing marks are still lined up. any input here? now im dissapointed.

 

Yep, time to rip the collar off the power screw.

 

BTW Wannadiesel,
Did you get the PM to you ,RE: KDPS and Bolts?

 

Alec, is it me or what????
I thought I said the same thing as you noted above.....

".....So for example, no matter were the starwheel is set, the silver spring will need less boost pressure applied to start it's downward movement and in turn begin to release low/no boost fuel earlier and faster....."

You noted:......

"....The silver spring is softer: it has a lower spring constant. That means that it will deflect farther for a given force applied to it......"

Am I having a seniors moment here....

Pastor Bob....

 

you definitely need to rip the collar off the full boogie screw. My pump was set with the boogie against the collar and the starwheel and smoke screw both full in. It was ok. this past weekend I went 1-1.25 turns in on the boogie screw and it's a lot different truck now GOt the idle knocked down nice and low too, so I have a little room to go more if I choose to

 

Well I have Thursday and Friday off, time to play test pilot with the full power screw, hope I dont blow anymore tires out

 

Bob --

This is splitting hairs a bit, but both springs can be set so that the AFC starts moving at the same manifold pressure. I.E.: both springs could be set so that the AFC does not add fuel until manifold pressure reaches 3 lbs (this is close to the stock setting). Once that pressure is reached, the silver spring will max out more quickly, but they can both be set to start at the same pressure.

As for your truck's lack-luster performance Apache -- it is easy (at least for me) to forget how different the pumps are from one to another. You can get the same overall setting with a very different combination of ACF orientation, smoke screw adj., and power screw adj. -- and it sure seems as though the factory spit them out set-up every which way.

Good luck with those fuel-screw adjustments!

 

Thats what boggles my mind, why are that way, as I mentioned my 250 is amazing compared to 350s performance. Im on a mission now to find the real truth. Ive becomed obsessed with this issue. Perhaps I should go back to a bicycle there much simpler to understand