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Old 06-24-2017, 01:56 PM   #1
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Timing info - where do i find it

Howdy,

im looking into advancing my pump timing for fuel economy and im trying to figure out my starting point.

so i look at quickserve and i see no easy answer. after clicking a number of ghosts chases, i found this -
copied from quickserve.


Advertised HP: 190 @ 2500

RPM

Secondary Adv HP: N/A @ N/A

RPM

Torque Peak (lb-ft): 475 @

1600

Pump Manufacturer/Model:

Bosch P7100

Governor Type: RQVK

Boost Control Provided: Yes

Fuel Pump Type: Inline

High Pressure Fuel Line ID

(mm): 1.8mm (0.07in)

Engine Application:

Automotive

SUPP Emission Test (gms/BHp-

hr BSNOx): 6.0

CPL: 1261

Certification Agency:

EPA,CARB

Mexico Sedesol

TEPA

Certification Year: 1993

Engine Cylinders: 6

Engine Family: B Series

Structure Code: 02 EBM

Manufacturer of Record:

Cummins

Dual Power Rating: No

FP Gear Timing (deg crank):

0 deg retarded

Engine Design Phase: Current

Product

Engine Aspiration: Charge

Air Cooled

High Altitude (>10K feet)

Rating: No

Managed Torque: No

Speed Sensor Location: N/A

Fuel Pump Mounted Angle: 35

degree.


so if thats correct, its at 0? tdc

somewhere i read most 5.9's are around 13.5* BTDC

what am i doing wrong?
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Old 06-24-2017, 02:20 PM   #2
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wow 0 degrees sounds really low... I dont know alot about cummins... the lowest end of the navistar DT-360 (5.9) had a setting of 15, the higher HP rated versions showed the timing at 19-21 degrees.. and appeared that going to that setting wasnt going to push the envelope of the EGT even under load... cummins may be a lot different.

is yours Pre-electronic? like a 6BT? 12 valve?

-Christopher
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Old 06-24-2017, 05:51 PM   #3
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yes, pre electronic, '93 6bta

the other real confusing thing here is the follow chart.

Diesel Timing

My cpl is #1261 that puts it over in the (e) column. and i don;t even know..... that column ends around 13.
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Old 06-24-2017, 08:03 PM   #4
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On a stock 6BT, factory timing was 6-7'degrees before TDC.

Optimal fuel efficiency comes at 12-16 degrees before TDC.

However, in stock form you're only going to see an increase in mpg of around 3 or 4 percent. So it's essentially a negligible difference.

Where you see a difference is once you've done an appreciable amount of power mods. (Not just turning up the fuel, but enough mods to the point where you've had to install larger injectors.) Then you have to change the timing in order for the mods to make maximum power, and in the process you get much better fuel efficiency.

And adjusting the timing is a bit complicated. There's more to it than simply moving the pump gear 7 degrees. From the factory, the timing may be off by as much as 3 degrees in either direction. In stock form, the timing isn't vital enough to be set very exactly. Doing it properly involves using a dial indicator to find TDC on the pump, the flat spot on a crank lobe in two places, using a degree wheel to precisely split the rotation between those two places, then timing the pump off that mark.
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Old 06-24-2017, 09:23 PM   #5
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Advancing timing may only get you a noisier engine and smoke. While timing may be 0 degrees at idle the timing advance in the pump will advance as engine speed increases. Be carefull if you advance too much you can blow a piston apart along with your egt,s skyrocket. It,s really best to talk to a real diesel expert before messing with the timing or you may be buying an engine.
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Old 06-24-2017, 09:52 PM   #6
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thanks for the input everyone!

i found timing number. it was stamped on the engine data on the motor. it says - 12 degrees.

ok

well that chart ends at 13.5 degrees for this CPL. maybe this isn't worth pursuing? its not going to be much of a change if i do it.
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Old 06-24-2017, 09:56 PM   #7
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Quote:
Originally Posted by turf View Post
thanks for the input everyone!

i found timing number. it was stamped on the engine data on the motor. it says - 12 degrees.

ok

well that chart ends at 13.5 degrees for this CPL. maybe this isn't worth pursuing? its not going to be much of a change if i do it.

Nah, just leave it where it's at. It isn't an easy job and if you're already at 12, that's pretty close to optimal.
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Old 06-24-2017, 10:33 PM   #8
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yeah,......... but im only getting about 7 mpg. lots of others are getting 10-11
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Old 06-25-2017, 08:27 AM   #9
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are the others with the same bus geared similar and running the same transmission / RPM / Speed? ive found theres a ton of variance in MPG based on various configurations / driving habits on similar busses..


-Christopher
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Old 06-25-2017, 10:53 AM   #10
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when i read about the benefits of retarding the timing - better economy, cooler eg temps, i got real interested. I'm on the bottom of most of the mpg claims. on my recent trip to Az, i used an an app to track fuel consumption. i've only done the the math a few times, since i'm better off not knowing.

just running, balls to the wall, 70ish, cummins 5.9, 4.7 rear, AT545, 2700ish rpms
7.5 MPG
if i turn on the generator, that drops to 6.5 MPG. i ran the gen overnight and it drank less than a 1/8th tank.

if others jump off a cliff, ya, i probably want to too
is 10mpg unrealistic?

hoping good news with the 1545 swap
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