OK, after I've installed my 3-in-1 gauges (boost, egt, fuel pressure), I'm ready to make the baseline adjustments (aka free adjustments) to my bone-stock 1st Gen. I have the aftermarket components (366 spring and Denny T pin) but I want to make the adjustments in phases, i.e. stock with turned up screws/etc. FIRST and baseline the performance results.

I've done a dry run (loosened screws, opened the pump top, removed caps/collars, cleaned, marked, etc.) and all are set in stock position. What I'd like to hear from the experts is the order for accomplishing the following, so that back-and-forth re-adjustments are kept to a minimum:

1. Turn fuel delivery screw (inboard back of the pump)
2. Rotate diaphragm/fuel pin
3. Turn starwheel
4. Turn smoke screw (top of pump)
5. Adjust idle screw
6. Adjust throttle max/limiting screw

In other words, should I do the above as they are listed or in any other order? Is it necessary to adjust the idle between each adjustment of the other parts (screw/wheel/pin)? Should I test drive the vehicle after each adjustment or make all the adjustments and test-drive afterwards.

Phase 2 will be to install the 366 spring and the Denny T.

Phase 3 will be for the turbo, exhaust, and injector upgrades.

 

Do you have gauges in the truck?

 

Yeah, I have the ISSPRO tach and the Glowshift Boost/EGT/Fuel pressure gauges. The truck is bone-stock.

 

Read the sticky about the runaway before you make any pump adjustments. Then I would turn up the full power screw till you find the runaway. Then back it off until it stops hanging in the upper rpms when you let off the throttle. Then you can adjust the star wheel and smoke screw as needed to control smoke and get the turbo spooling at the right time.

 

Thanks Bill.

On runaway, what's the best way to stop runaway. I read about blocking the turbo with a 2x4 or a box but that seems crude, is there another way, like maybe tripping the fuel solenoid or something.

Also, do you recommend rotating the fuel pin before (or after) I turn the fuel delivery screw?

 

There is no other way to stop a runaway use wood not a box as it might get sucked into the turbo. You can rotate the fuel pin at any point that is up to you.

 

IMO, the order of pump tuning/tricks has a lot to do with what you want the end result to be. For example, if your truck works for a living, there won't be much turning of the full fuel screw, but lots of AFC tuning. If you're after max power, then look for runaway with the full fuel screw and tune smoke with AFC adjustments. As for finding runaway, I always tuned with the truck running. I backed the stop nut on the full fuel screw all the way out and the idle screw all the way out as well. Then I ran the ff screw in a turn at a time, bumping the throttle wide open every turn of the screw to check for rpm hang. Eventually, rpms will hang uncomfortably and I'd back the screw out a half turn or so, and then set the idle screw appropriately. Then I would tune the AFC to limit low end fuel. In your instance, I'd add the 366 spring first and tune from there.

 

The intercooled trucks tend to run out of threads on the fuel screw before approaching runaway. If you encounter a strong resistance before runaway, don't force the screw in further. A new, longer screw can be purchased from Cummins, or weld can be added to lengthen the screw about 1/8 to 1/4 of an inch.

 

Thanks G1625S,

This engine will be going to my 12K# motorhome and I'd be content with just an additional 100HP (i.e. 260HP total, give or take a few). My mods will take MPG in mind seriously; I don't intend to drive this 25ft motorhome aggressively.

Good idea on the installing the 366 spring first, after all it's not an "adjustment" item like the rest. Who knows I may not even need a Denny T pin or any other mods.

I like the procedure that you outlined. Thanks.

 

Thank you dodgenstein. It is comforting to know the 'running out of threads" before runaway; however, just a precaution I'll have a 2X4 ready :-) LOL.

Anyway, after I removed the fuel screw cover, I see that the jam nut is already against the collar (is this stock?). There are 8 threads going in ahead of the jam nut. Having removed the collar, it will give me about 4 additional turns, before the jam nut loses traction with the threads. Would that be enough to achieve my 260-HP power goal?

 

[QUOTE=ClassA4x4;2896262]

I've done a dry run (loosened screws, opened the pump top, removed caps/collars, cleaned, marked, etc.) and all are set in stock position.


Just wondering, How do you know all the setting are in the stock positions?

 

[QUOTE=Robofig;2896832]No I don't know for sure that they are in stock position. All I know is they were still sealed, rust-welded :-), and were not in the desired setting setting for optimum power.

 

Motorhome, gotcha. I don't know that you'll be able to put 260 to the wheels moving that kind of weight without melting the ol girl down. The good news is, the torque to horsepower ratio is about 2:1 on a 1st gen engine, so even adding only, say, 50 hp will net you nearly 100 ft/lbs of torque, and that's the number that will put a smile on your face getting a heavy load moving. If it were my rig, I'd toss an hx-35 on and the 366 spring before anything else. Those mods with some clever AFC tuning will have you up on boost quickly which will keep egts in check. Once a 12v gets hot, it's hard to cool it off without getting out of the throttle, but if it's up on boost quickly, it'll stay cool. Sounds like an awesome project either way What tranny you runnin?

 

indeed, the 366 will be going in first!

the engine is mated to a stock smooth-shifting 47RH/NP241, and driving a Dana 60/70 4.1:1 gears and equipped with ARB lockers.

an HE351CW is what's in my mind but I haven't found that great deal on it yet.

 

better get at least a 2x6