Pump recipes

[CAROLINA CUMMINS]

As soon as I get my guages installed I'm going to crank this baby up. What I want is more low and middle end fueling. I think I know all the stuff to turn up, but I want the best setup for low-middle range power.







Thanks, Steve

 

[BushWakr - RIP]

Hey Steve,



Remember your other question about EGT's and housings.....

Well if you want to set up for good low/mid range your going to see some higher EGT's... not nasty, but higher due to the pump settings (more fuel=more HP=more EGT's)



To start you out,



Set AFC diaphram to max setting.

Set Starwheel down (CW) 1 turn.

Set smoke screw down (in CW) 3/4-1 turn.

(Leave full fuel screw alone for now... )



You should get a "puff" of smoke as you nail the throttle, this initial 'shot' of fuel gets the turbo spooling (smoke screw does this) This basically affects the first 50' as I like to say.

Then as the boost begins to climb, you will feel the fueling come on. Check your boost guage and watch when you feel the surge/smoke. The starwheel will determine at what psi your fueling (via the AFC) starts to dump in. I have mine currently set so that it starts to fuel harder at around 8psi. From that point the fuel comes on quickly, and hits max by 10-11psi.

The 16 housing will let you reach that threshold (eg: 7psi, 8psi or whatever) quicker. By the time you have 1/2-3/4 of your max boost you should see your smoke cleaning up to dark grey.



The one issue I can't recal at the moment is that some of the earlier trucks had larger 9mm injectors. (much better than the stock injectors that came with my later 1st Gen)

These meant that there was less "meat" between the injector bore and the exhaust/intake valve opening. Excessive EGT's repeatedly can cause cracking of that area of the head.

To me, excessive means beyond 1250*F for extended periods.



Go with the 16cm housing, no problem, try your settings above as a starting point. Remember that the full fuel screw sends fuel across the power band, with a larger portion of the "increase" to the low/mid range, and resultant smoke/EGt's.



Does this help?? If not let me know or someone else can jump in here to clarify or add something.



Bob.

 

[CAROLINA CUMMINS]

Thanks

I really need to get a tach, I just ordered my boost and egt guages on christmas. I'm trying to find out about that 16cm exhaust housing because I can put it on while I'm putting my guages in.







Thanks, Steve

 

[JLEONARD]

Steve,

I have an early 91 with no intercooler as it appears you do from your signature. I think these are set up a little differently from the factory than the intercooled trucks from what I have read in the Mitchell repair book I have. I know the turbos have a different size compressor turbine for example.

I installed a 16 cm housing on mine and gages and left it alone for a while to establish some sort of "norms".

I recently made some adjustments under "formulas" guidance that really made a nice improvement in drivability and power thru-out the rpm range.

I rotated the eccentric 90 degrees to it's "almost max" position.

I moved the starwheel cw 1/2 turn.

I didn't touch anything else yet, and might not.

I get a small shot of smoke as Bushwakr described when I nail it in the 1000 to 1300 rpm range, then it cleans up pretty well.

The truck pulls really hard now. . I can feel the truck almost vibrating with power under hard accelleration... ... boost comes on much more quickly and is almost instantaneous in 5th at 45 mph and above.

Max boost comes in much sooner and increase by 2 psi.

EGTs haven't changed all that much unless I really lug up a hill... but they still never reach 1100 (without a load).

Egt rises much quicker, and takes longer to cool down at idle to get below 300 before shut down.

Hope this helps. Have fun playing around!

 

[formula]

I've got a little something to add here. It should be noted that all of the previously mentioned pump adjustments are very easy and completely reversible, if desired. A couple of tweaking sessions may be needed to get it to where you want it. Don't forget to record the initial settings and any changes you've made.



Jay,

Good to hear from you again



Cheers,

Sean

 

[PPeters]

Concerning 9mm tips... FWIW



I spoke with the friendly tech at the local Bosch pump shop about injectors. He said that the 9mm tips are supposedly only found on test engines from Cummins. He also indicated that these motors were supposed to never find their way into public consumption. This info came to him from the Cummins rep. The reason he knows this is the local GE locomotive shop has several B engines in the shop, and they all have 9mm injectors. Apparently GE picked them up on the used market. GE comes to him to get the 9mm's.



Just passing it along, if anyone has other info, chime in!



Pat

 

[CAROLINA CUMMINS]

I can't remember where, but somewhere I read that all non-intercooled 89-91. 5 have larger inj than 91. 5-93.







Steve

 

[PPeters]

OK, now I'm curious. Gonna call Bosch tech and quiz him some more. Let everyone know what I find.



Pat

 

[PPeters]

OK, got some clarification



To start with, 9mm were in 91 and earlier



According to Bosch rep, there should not be any 9mm now. Cummins redesigned the head to the 7mm, but continued to sell engines with 9mm heads (preexisting stock?), so they are out there after 91. He went on to say that you can get sleeves to install 7mm into a 9mm head, and they also have (with Bosch's blessing) machined down 9mm injectors to be installed in 7mm heads.



I'll shut up now



Pat