Pump timing accuracy

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I am getting Lil' Mack in the shop next week to have a compression check and injector inspection/upgrade. I questioned the service manager at GCL Diesel about how he sets pump timing and mentioned the extensive talk about 1. 25mm vs 1. 35mm and the spill port technique on the TDR.
The last time I had my truck in to get the timing set, they gave me a worksheet with the timing reported in degrees of crank rotation BTDC. I noticed back then that a spot on the line going to #1 injector had been buffed of paint. So today I asked about how he got timing.
He told me about the spill port and how the pump has some dynamic clearances that will change the timing slightly while running from what you set and the important timing is when the injector needle is lifted from the seat. Which is true, if the injector is weak or strong in the internal tension, the pump will open the injector sooner/later than anticipated.
They have a pressure sensor that they clamp onto the outside of the injector line that senses when the injector opens to determine injector timing BTDC in degrees!!.
The shop report from Aug 95 was documented as follows. Mileage 181,524 IN Timing 5. 4 @650 / Max speed 2800. OUT Timing 10. 0 @650 / Max speed 3000. Aneroid screw up 1/2 turn. Boost IN 19 PSI / OUT 19 PSI.
I just found that this is an interesting way to check the injector pump timing and thought I would share it.
If the engine checks out for compression, the uprated injectors are going in!!. Funny thing is that they are cheaper than the stock ones. #ad
around $599 CDN for the set. Not bad!


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Jason's Lil' Mack - 89 D250LE 2WD 5 Spd 3. 55 Reg Cab. K&N,"tweaked pump", 3. 5" Exst straight,E&M Custom seats. Bosch H4, PIAA 80W/80W HdLites. Bosch 100W Driving. Bosch 55W Fogs.
229,000 miles (366,000 Kms)
7550 Hrs.

 

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Hi Jason,
Just a question-Is that GCL in Edmonton or the one in Calgary?
Doug

 

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Hi Lil' Dog.

Can you ask if they check the timing with the pressure sensor while the engine is running?

If so, how do they get the actual timing reading?

I'm thinking they have to accurately locate TDC and mark the balancer and then use a strobe light which is triggered by the sensor which 'feels' the shock of the injector letting the fuel in.

If your uprated injectors work anything like mine do Lil' Mack will be bulldog tough and run like a greyhound!

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'93 W350 Club Cab, 5 sp. , Factory Options: LE, 4. 10, LS, 7600 lb. rear springs, tachometer, front stabilizer bar. Mods: Banks stinger plus, Linex bedliner, 25,000 lb gooseneck, 10,000 lb receiver, Tekonsha brake controller,
PW injectors.

 

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Doug
The one I am dealing with is in Calgary. I think that the one in Edmonton would be the same.

Jason

[This message has been edited by Lil' Dog (edited 06-09-2000). ]

 

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Mark93
The way you described the timing measurement is how he explained it. I just wasn't too clear in my post about how it worked. There are marks on my balancer with a paint marker and they must know how many inches/degree rotation are on the balancer.

GCL cautioned me that the power increase will not be as noticable as I don't have an intercooler. He estimates about a 20-30 HP increase with stock pump adjustments, and more like 50-75 HP with an intercooled 92 and up engine. I guess the intercooler upgrade project will have to be moved up to the top of the list soon if I want serious FORD STOMPING power. #ad

Definitely PYRO and BOOST GAUGE time!!!!

Jason

 

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Brought to top... Doug and I had a lengthy discussion about this topic over coffee last Saturday and have a couple questions for the gooroos(sp?).
1) Has anyone equated the spill port timing measurements to degrees of timing???
2) What are your feelings on setting the timing via the pressure sensor method?

Both Doug and I would like some input on this as everyone seems to ignore this type of pump setting method for the mechanical timing method.

 

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Ok... let me toss my $0. 00 worth in:

The timing meter you describe is called a "pulse" type meter. There is an electrical change in the injection line when the physical shock of injection occurs.

This meter normally reads crankshaft position via a thin machined slot in either the dampner or flywheel, and then calculates timing in degrees by comparison of rpm and difference between the two sensor inputs. However, there is no timing line on the dampner on the Cummins, and none that I know of on the flywheel. There are two gaps in the dampner, but those gaps are not precise, nor is there a bracket to hold the sensor. They are the input for the tachometer. The dampner does not fit accurately on the end of the crankshaft. if you loosen it's mounting bolts, the dampner will turn back and forth several degrees.

If there is a timing sensor probe device on the flywheel, I am unaware of it's existence. I have looked for, but never seen one, nor does any documentation I've read mention or even allude to one.

Without this, there really is no way determine the true injection timing via a pulse type meter.

The method of timing, which uses the TDC position on the engine, and then locking the pump at the desired position after the beginning of injection, is quite accurate, and the amount of slack in the gears can be compensated for at installation time. One merely applies some torque to the pump against the direction of rotation, which takes up the slack in the gear teeth, and then tightens the pump down.

This method should obtain a true injection point within a degree of desired - accurate enough to perform very well. It, of course, is dependent upon the pump being accurately set by the technician who works on it, the TDC pin being set accurately (we find that at least 1/2 of them aren't), and then the installer understand what he's doing and compensate for drive gear backlash.

 

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The pulse method could be improved if you determined top dead center on the damper using the exhaust valve drop technique, a dial through the injector hole or you assume that the TDC pin is accurate.
I doubt that most shops, including the one I used, varify TDC with anything other that the pin. The only thing that the pulse method can help with is the deterioration of the injectors over time, which is compensated with advancing/retarding the timing.
A very interesting topic!!!

 

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I had the exact question about spill port mm's converting to degrees. When I timed my engine using the positive stop method I found that . 2mm plunger lift is equal to about 4 or 5 crankshaft degrees. This was near TDC and I do not know if the relationship of plunger lift to crankshaft degrees is linear or not. This relationship would be governed by the shape of the cams on the VE pump's cam plate. I would guess the relationship of plunger lift to crankshaft rotation to is sinusoidal because that pattern is best for smooth energy transfer and would be the easiest on the mechanism but it doesn't HAVE to be sinusoidal (that is the cross section of the cams looks like a sine wave pattern-the beginning of a sinusoidal ramp is very nearly linear). If the relationship was linear the cross section would more resemble a triange with a rounded top. By eye it may be difficult to tell the difference.

Hey POWER WAGON, you have probably seen lots of these apart, what do you think?

Are there any published data on pump degrees to lift (shape of cam data)?

Next time I time my engine I think I'll plot plunger lift verses crankshaft degrees and see what it works out to be.



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'93 W350 Club Cab, 5 sp. , Factory Options: LE, 4. 10, LS, 7600 lb. rear springs, tachometer, front stabilizer bar. Mods: Banks stinger plus, Linex bedliner, 25,000 lb gooseneck, 10,000 lb receiver, Tekonsha brake controller,
PW injectors.

 

[Archive]

Originally posted by Lil' Dog:
The pulse method could be improved if you determined top dead center on the damper using the exhaust valve drop technique, a dial through the injector hole or you assume that the TDC pin is accurate.
I doubt that most shops, including the one I used, varify TDC with anything other that the pin. The only thing that the pulse method can help with is the deterioration of the injectors over time, which is compensated with advancing/retarding the timing.
A very interesting topic!!!

Although it's only a guess on my part... the changes in opening pressure do not affect timing enough to affect performance. The reduction in spray pattern efficiency is far more worrisome.

 

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Originally posted by mark93:

Hey POWER WAGON, you have probably seen lots of these apart, what do you think?

Are there any published data on pump degrees to lift (shape of cam data)?

Next time I time my engine I think I'll plot plunger lift verses crankshaft degrees and see what it works out to be.

There's no published data that I know of. However, the cam ramps are the steepest AFTER closure of the spill port - more lift/fewer degrees. Changing timing by . 2 MM (that's quite a bit) should not be 4 or 5 degrees. It is a VERY small movement of the drive shaft on the VE pump. In fact, it's so small that with a 1 foot long wrench, it's difficult to move that . 1 mm on the dial indicator. My guess is that it's more like 1. 5 - 2 degrees engine. As the . 01 graduations go by on the indicator, you cannot feel the motion of the wrench turning the driveshaft. You only apply force and the indicator moves. No sense of movement under . 1mm travel.

 

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Hey POWER WAGON.

I changed my timing by . 2mm (advanced) from 1. 15 mm to 1. 35 mm when I found TDC by the positive stop method and I moved the pump very little (the reference mark on its flange only moved about 1/16") to obtain timing change. After I adjusted the pump I then rotated the balancer ( normal engine rotation 2 revolutions)so that the dial indicator once agian read 1. 15 mm (the original reading) the difference calculated to 4 or 5 degrees. The 4 or 5 degrees I referred to must have included some gear backlash.

BTW Power Wagon what is the maximum recommended advance for the engine.

When the KSB is on in the morning the power is noticeably better.

 

[Archive]

Originally posted by mark93:
Hey POWER WAGON.

I changed my timing by . 2mm (advanced) from 1. 15 mm to 1. 35 mm when I found TDC by the positive stop method and I moved the pump very little (the reference mark on its flange only moved about 1/16") to obtain timing change. After I adjusted the pump I then rotated the balancer ( normal engine rotation 2 revolutions)so that the dial indicator once agian read 1. 15 mm (the original reading) the difference calculated to 4 or 5 degrees. The 4 or 5 degrees I referred to must have included some gear backlash.

BTW Power Wagon what is the maximum recommended advance for the engine.

When the KSB is on in the morning the power is noticeably better.

I don't know. The timing specs for the B engines vary from 1. 15 all the way to 2. 00 for industrial engines. If the engine runs better with more advance, I guess you could try more.