I've been tossing this over in my head for some time, even had the pump out a couple times but haven't have the guts to try it yet, mostly because I'm in a crunch for time when I get it out and don't have time to do it twice. But I think I've finally figured out how to test/calibrate a 5521 series pump with a 5068 cam ring installed, and if my guestimations are correct, this could be valueable in several aspects.

For those who aren't familiar, the 5068 was released in '94 on some of the 6.5 trucks and was shortly thereafter discontinued (before '95). The only real difference in the two pumps is the cam ring, the 5067 series all use the 32096 (superceded from 30909) and the 5068 alone used the 30501. The calibration tables and PCM PROMs are both different as well. After taking some measurements and comparing the two rings, here's what I came up with. The 30501 cam ring has about the same lift and slightly less duration than the 32096 does, its just a little faster ramp.

The optic sensor sets the range of the cam rings lift the pump will operate in. On a 5521 series, the set point is 30mm(3) @ 1500rpm, low idle check point is 11.5-12.5mm(3), and full delivery is about 83-84mm(3) @ 2000rpm. Now what has to happen to make the cam ring swap, is you have to set the optic sensor at a point where the low idle check point yields just under the expected 11.5-12.5mm(3). Why lower you ask? Becuase the PCM still has to be able to make the truck idle, because the cam ring has a faster ramp, the PCMs fine tuning adjustments will be slightly amplified and will be unable to maintain steady idle if set higher. I expect, that once the optic sensor is set to this point, the 1500 rpm check (29.5-30.5 expected) will yield 31.5-32.5, and the full out check at 2000 will be pushing 95mm(3).

I've got 13 pumps scattered right now, starting reassembly in the morning, 12 5521s and one 5068. So, what I"m going to do is test my theory on the 5068 pump by entering it on the computer as a 5521, setting and checking to see if it does what I expect, results to be posted tomorrow!

Umm.. Tex,
Can I have one of these experimental pumps? 93 mm3 sounds like good numbers. Also what would it take to make my old 4068 do that? merge it's cam ring to a 5521 and calibrate it?

PS I knew you had a HO DS-4 up your sleeve.

Chris, what was wrong with your old 5068 again? Was that the one with the bad optic or the broken FSOL? Either gotta build that one, or swap the cam into your 5288 and play with the optic setting until it works, I can probably give you a pointer on approx where that setting will be tomorrow.

If I use the cam ring from the 4068, I could probably find a newer# core to put it in and just not open the F sol. This is really going to go great with the tranny mods.

Have you checked into Stanadyne's reasons for the early discontinuance?
Be interesting to know that..

Would you like to try my truck as a guinea pig?

I estimate 93mm3 would be 309.47 HP. Would an aftermarket program have to be utilized to see that?

I too am running out of fuel, and out of mods to make if faster w/o going into the engine, or doing major fabrication. I would be interested if this works to have you make one for my truck! I figured w/ injectors and this mod, I should have more than enough fuel for more boost! :ro) Right now I am prob. makeing around 280 hp with all I have done, I would like to reach the 330 or maybe even 350 one day. So a detailed list of what all I can do to my injection pump would help alot! Let us know how it goes!

Wow, if I had some extra pumps to give you guys to try out I would! ;)

I guess I overestimated myself, 13 pumps take a while to build, but I finished them all today, first one is mounted to the stand so i should for sure have some test stand results to post tomorrow, hopefully real world test on my truck this weekend.

GMCTD, I have pondered and asked that very question, and never got a real answer.

How come the 5068 pump won't work in place of the 5521 without a computer swap? I know they run like crap with the wrong combination.

Well - here's the scoop -

Stanadyne traditionally offered two separate GM Inj Pumps each year - one emissions for the 'C' engine, one hi output for the "J" engine.

This was continued with the release of the EFI DS4 in '94 - the 5067 for emissions, the 5068 for hi output.

Suddenly, GM reported hi volume failures in the EFI trucks, with metal particles in the fuel tank(s), fuel lines, lift pump, fuel filters, IP, fuel return lines - the whole system.

Upon inspection of the returned pumps, Stanadyne discovered the steel rollers were disintegrating against the camrings, damaging the rollers, blocks, camrings, and everything else.

Eventual solution was ceramic rollers, blocks, and discontinuance of the 5068 .
Only one Inj Pump was offered for both emissions and hi output engines.

The improved rollers\blocks were also implemented in the DB2 series.

All Black Label IP's repaired in the field, and all returned to Stanadyne, got the new rollers\blocks, indicated by the Green Tag, then by the new Blue Label.

My question relates to the failures - which IP caused the most failures?

The standard 5067, or the hi output 5068, with it's aggressive camring?
Or were the failures equal among the two?

The tsb should point to the real culprit, but the fact that the 5068 was quickly discontinued seems to be the smoking gun.

...The improved rollers\blocks were also implemented in the DB2 series...

All Black Label IP's repaired in the field...

My question relates to the failures - which IP caused the most failures?
...the fact that the 5068 was quickly discontinued seems to be the smoking gun.OK, here's the scoop the way I heard it...
DB2s did not recieve updated rollers or shoes, steel rollers are still a must in a variable Start of injection pump because the rollers actually slam into the profile of the cam ring, on a DS pump the rollers stay in constant contact and the real reason for the switch was to reduce the weight of the rollers to keep them held against the cam ring at higher RPMs.

Second, NO black label pumps were repaired, they were all returned to stanadyne which replaced them with new updated blue label pumps and the black labels were scrapped. Blue Tags indicated the first round of updates for the 5067, then 5288, then the green tags.

My theory on the discontiuation of the 5068s is not a higher failure rate, its hard to say for sure, obviously there were a TON of failures early on, but rather that Stanadyne was beginning to realize the capabilities of the DS platform, and that PCM changes alone could effectively designate HD and LD applications, and it would be much easier to continue updating a single pump instead of two series.

I estimate 93mm3 would be 309.47 HP. Would an aftermarket program have to be utilized to see that?Let me just say, I did mention that a stock 5521 series pump will put up 84mm(3), but a stock 6.5 PCM will never demand that much, need a chip to reach that high of quantities, and the same is true with even the "H.O." DS pump. The reason I speculated 93mm was to show a change in top end output, since a stock PCM goes only up to about 64mm, a H.O. DS might put up about 70 for a 10% gain, but not add an extra 100HP, more like 15-20.

Is the cam ring and the data disk the encoder reads one and the same? If so, the '94 HD prom would have to be used, if not, any year could use it.

Data disc is just a disc that rotates with the driveshaft of the pump, never been changed and they're all the same, the cam ring is what the optic sensor is bolted to.

I"m gonna steal some pictures and just hope they don't mind... http://www.realdiesel.com/ds4pump.html

http://www.realdiesel.com/images/ds4pump_006.jpg

This is the inside end of the drive shaft, the shoes/rollers move inside the 4 notches, the data disk is the thin plate just underneath. Behind that, inside the guys hand, is the transfer pump.

http://www.realdiesel.com/images/ds4pump_014.jpg

This is the cam ring, which goes around the end of the drive shaft so the eccentrics can drive the rollers/shoes which push the pumping plungers. As you can see, the eccentrics are very mild, so the slightest difference in ramp angle makes a big difference.

http://www.realdiesel.com/images/ds4pump_019.jpg

And here's the ceramic rollers, extremely light, they stay in constant contact with the cam ring.

Would you have to use to '94 hd prom then? I'm vague on this what in the '94 pump is dependent on that old prom?

Hey TDG- Could you make a list, from oldest to newest, of the different pump models and tag colors? You started to make that list once earlier in this thread, but it was incomplete.

Would you have to use to '94 hd prom then? I'm vague on this what in the '94 pump is dependent on that old prom?5068 pump has a different cam ring, and the optic sensor is set at a different point, PCM has be programmed to match to make the pump operate properly.

After some observations on the test stand today, I think I know why they decided to discontinue the 5068. First reason, is the 5067/5521 cam ring offers enough lift to meet fuel delivery requirements for HD applications. Also, I noticed when I calibrated the 5068 pump to 5521 specs, the optic sensor had to be backed off a couple millimeters. This to me says they 5068 pump has the Cam Pulse from the optic sensor closer to the start of the cam ramp, which tells me these pumps are more sensitive to CTIME variations (long) at higher RPMs, which could more easily affect Start of injection timing and cause power/balance problems.
Remember this pump was still in the experimental stages when GM bought them, Stanadyne knew that, they still had to learn a lot about the monster they had created, and they learned the hard way ;)

Here's your list Wade....
First, Black nameplate 5067, then blue nameplate 5067, then blue nameplate and tag 5067, then 5288, then green tag 5288, then 5459, and finally 5521.
I can't remember the exact number of updates, but I believe its over 50 between all those model/tag changes.

Oh, did I mention I got to try out the H.O. DS pump today? I already stated that I had to back the optic sensor off a bit to get it set right, right at 31mm at the normal set point for the 5521s. Low idle delivery 12mm, right where I wanted it, and at the top end, it was an appreciable gain, about an 8% increase in high end fuel delivery, just edging 90mm @ 3400 WOT where a stocker would make just 84mm. What impressed me was the sound this puppy makes with that cam ring, holy crap! Sure sounds like its making a lot more power, can't wait to hear what it sounds like on the engine ;)
This mod should work very well coupled with Hi-pops, because the injection duration is the same as stock, just more fuel, unlike a chipped truck that just stretches the duration to get more fuel. Quicker burst of fuel, better atomization, more power? We shall see...

Mine was running @ 79mm when i first installed the chip... 90mm is sounding even better though!

I think 90mm would absolutely demand you drop compression, either that or you will drop the crank.

Is 20:1 low enough? I don't care to see the harder starts and less low end power associated with 18:1

Tex, I'd trust one of the HO pumps more if you put it together instead of me. What do you think?

Now, when you say the optical is set at a different position on the 5068 cam ring, and the PCM has to have it programmed in, could a bidirectional (techII) do this using the "time set" function?

Are you talking about 10 over head gaskets? I don't, you might get away with that...

I would certainly reccomend that nobody try this without putting the pump on a test bench to set the optic, it would be near impossible, I don't know if I would even try it. The faster ramp makes it a very touchy settingand you can't use the center position or the line scribed on the cam ring for a reference, its too far off.

The optic is set to a different position on a 5068 cam ring in a 5521 application, this is a work around to get more power without a chip, so changing the computer to 5068 would be counterproductive. Time set procedure would be exactly the same procedure, the pump would just have to be advanced ever so slightly more to compensate for the new position.

TDG.. or anyone else...

As I have a 98 and a DS$... not sure what particular else I have .. but it sounds like most of these mods are for 94-95 era truks.. is that correct...

And what alterations are available for the 98's? I have seen few.. but a couple of options...

Pete

This mod is for use on 5067-5521 pumps. So that means all 95-up applications, and all 94s that do not have 5068 PCM Proms, which would include your '98 GSlam.

All it is, is taking a '94 HD 5068 cam ring, swapping it into the more common 5067-5521 series pumps to make a H.O. DS pump and keep factory PCM programming.

The optic is set to a different position on a 5068 cam ring in a 5521 application, this is a work around to get more power without a chip, so changing the computer to 5068 would be counterproductive.Ok, That opens the possibilities up.

[QOUTE=Texas Diesel Guy]
Time set procedure would be exactly the same procedure, the pump would just have to be advanced ever so slightly more to compensate for the new position.[/QUOTE]Is this a yes on having time set done? or could it be installed like a regular pump and TDCOL initiated?

Hey Tex. Could you read my last post under "Hard Starting after new Pump and PMD" and see what you think. Thanks in advance!

I don't understand where I"m losing you, maybe I'm explaining this very well, you guys just have to understand I spend 5-8hrs a day dealing with just this pump, so sometimes its hard to explain to someone who doesn't have the same understanding and familiarity, what exactly it is I"m trying to accomplish. I'm doin' my best though ;)

Think of it this way, you got your 95-99 truck right? pump is a 5521 and ECM of course is calibrated to match the pumps capabilities right? What I'm doing is just taking 5068 pump, and calibrating it against 5521 tables to make it work in a 95+ application. What I was saying about the optic, is that if you took a stock 5068 and wanted to use it in a 95+, you would have to bump the optic sensor the opposite way (driver's side) to make it work. TDC offset procedure will be EXACTLY the same as if it were a regular pump, but, since you had to bump the optic sensor back, you would notice the pump housing will have to be advanced a little more to get it right.

Something I forgot to mention about cal-testing this H.O. DS pump, cranking delivery minimum spec is 36mm @ 150rpm, a 'good' 5521 will make 45 or so, the H.O. pump I tested made 55mm (min spec on a 5068 is 50mm), should help with startability in a dropped compression application.

So I could just put a stock 4068 in with my '95 prom and bump the optical driverside and the pump housing as well and have it work? I was confused as to what did what.

essentially yes, but its a VERY finicky adjustment, and you have no real baseline to judge from. I suppose if you had the time and a scan-tool it would be possible.

I will be quite surprised if you can make any type mismatch of components work right. The computer/injection pump combo must work as a unit to function properly. Try it, then let us know.

Sounds to me that is what he is saying he is doing. First on the bench and then on his truck. I'm interested to see what it does and if it can be done for others cost wise. But I am willing to wait and see or read, I should say, What TDG comes up with.
BTW I'm back home now from Turkey too.

Diesel pro makes a good point, just because it looks like it could work on the test bench, a test bench is not an engine, and has no ECM, it doesn't react to what the pump does. This was a needed first step just to see if it would be even close to possible. Getting it to idle right will be the biggest challenge I expect, pump will be more reactive and could cause problems, I do expect it will work, for one, at low delivery quantities, the start of injection will be slightly retarded from stock, this will mellow the the quicker reacting pump a bit and might just be enough to make it work, and idle quieter...

Hopefully Bowtie, you will all be able to see as well, I wish we had the dyno already setup so I could do a before and after run, but I'll try and get before and after 0-60 vids instead maybe.

By the way this would not be an alternative to a chip, unless custom built pumps are cheaper than than a reprogramed computer. Seems like a workable project though. Anyone need a 5068 for this project I have one built, and ready to go. Doesn't the 5068 have a few other parts that are different from the 5521?


Camrings are like engine camshafts. Got to have the perfect match if you expect it to perform.

Wonder if the fuel pressure regulator could be modified so that the pressure spikes sooner and then levels out. Might improve low end injection quanities. At least you won't have to take the pump apart to fiddle with it.

Looking for Injection pump images try:

http://www.realdiesel.com/ds4pump.html
http://www.jhdiesel.com/ds4.htm
http://www.geocities.com/MotorCity/Show/3753/6_5_litre.htm

It may not be cheaper for a guy on the street, but I'm not paying anything for this upgrade so its a heck of a deal for me. It would depend on the shop you purchased from, you'd have to do some explaining to get what you want, but I can't imagine them having any trouble trading a 5068 for a 5521. Cheaper or not, its still an alternative.

The only other part that is different between 5068 and 5521 is the little orfice plates in the H&R, they don't make any difference that I can tell.

I don't agree with your remark on the cam shafts, afterall, what do most guys change when they want more power? They go to a bigger cam shaft...

Raising transfer pressure won't raise fuel delivery, all that does is fill the pumping plungers, and once they're full they don't get any more full.

Oh, and I won't be able to test this H.O. pump until next weekend I"m afraid, there's a Mack truck in the bay so I can't pull the truck into the shop to work on it...bummer...

Not necessarily true, TDG - the point on the ramp at which injection pressure is reached is determined by the pressure in the plunger bores at the start of the ramp, which is transfer pressure.

As an example -
If the plungers are filled at 25psi at ramp start, rollers may require 60% travel up the ramp to develop injection pressure.

If the plungers are filled at 125psi at beginning of the ramp, rollers may only require 45% travel to inject.

That is true of any pump - if more volume is needed, put a second pump in parallel.
If more pressure is needed, place the second pump in series, inline.
The pressure out of the second pump is then based on pressure out of the first pump.

In the Inj Pump, desired pressure would occur sooner in the injection cycle by the amount of pressure in the plungers at the start of the cycle.

Fuel rate, or quantity, could also increase - desired injection pressure is reached sooner, advanced to 45% ramp, while PCM is holding FS open based on the expected 60% ramp point.

The EFI system must need this slight advance at higher rpm, or transfer pump pressure would have been more closely regulated than 25 to 125psi.

...I know where your coming from...but its not quite as you think.

Inside any hydraulic head, there are charging ports and discharge ports for each cylinder. On the rotor, there is just one of each so fuel can be delivered to each cylinder one at a time in sequence. During operation, the charging port is exposed to the rotor, transfer pressure forces fuel to fill the pumping plungers, the port is closed as the rotor turns and then the discharge port of the coordinating cylinder is exposed. During that momentary entrapment of fuel, what ever transfer pressure filled the plungers, becomes a non issue. Fuel cannot be compressed, so you can't force more fuel in and you can't maintain pressure inside. Your 45% ramp climb before injectors open is quite exaggerated as well, Once the rollers start pushing the plungers fuel is moving out of the head, pressure builds in the line and then in the injector, and even if you could get a head start of even 100psi, the pump will pump a fixed volume of fuel.

Some of the most sophisticated engines in the world would not be hoot without a precision ground cam to fit a specific need. The camshaft is one of the most difficult tuning parameters an engine builder faces. To say just put a bigger one in shows your knowledge of engine dynamics. The injection system revolves around the same problems but is predictable. Engine volumetric efficiency is has to be proven with a running engine. Bigger is not always better.

I'm not even talking about camshafts, the point I was making with that statement is that there are different cam shafts to suit different needs. Obviously a camshaft controls a lot more aspects and has much more effect on an engines performance. Don't get on here and try to undermind what I"m saying because you think you know more about camshafts than me, maybe you do, but this is not a camshaft thread, I'm not a camshaft guy, I'm a pump guy and thats what I'm talking about.

A hydraulic line with a gage and a valve between the gaged line and the pump can be pressured up to any intrinsic level, the valve closed, pump stopped, and the gage will indicate the pumped pressure in the line, until such time as the valve begins to leak, or is opened.

The plunger-to-bore and head-to-rotor clearances are precisionly minimal, and at operating rpm, essentially offer no leakage when rotating, such that the pressurized plunger bores would retain transfer pump pressure until the camring forces the plungers inward.

Similarly, at operating rpm, centrifigual force should sling the plungers\blocks\rollers outward into the camring, but the precision plunger\bore and rotor\head clearances would create hydraulic lock on the compressed plungers, which would then require pressurized fuel to allow outward movement, as well as charging the bores for the next cycle.
Also, if charging\discharging system remains pressurized, no air can enter the system.

The above scenario is hydraulically probable, but not proven.
Remember, I'm talking PCM dynamics, not rigid flow-bench calibration.
Rpm, pedal angle, Boost pressure, ECT, IAT, all play a part in how long the FS is energized in each constant-beginning variable-ending inj cycle.

Not an easy dynamic to duplicate on a flow-bench, I would think.
But, adjusting transfer pump pressure on the bench could show any advance\retard resulted from higher or lower pressure.

Probably wear out the transfer pump much faster.

Wish I could get some flow-bench operation\training.

From my end, I've built a harness to allow monitoring FSD and IP signals, referencing CPS signal, without creating any intrusive influence.
Allows checking actual PCM controlling relationship, as well as for delay, loading, noise, etc, in the setup with short oem FSD harness, compared to various lengths of extended harness for remote mounting.

Checked at two feet and at eight feet - doesn't appear to create any significant changes in the signal, drive, or feedback lines.
Currently determining method of comparing FSD resistor functionality.

gmctd,

Recently, I had the opportunity to see my signal on a scope. It was to compare whether my 42" of spliced in FSD harness made a difference in the signal length. IIRC my opening signal was drawn out further, but the overall signal was a fraction shorter than the perviously scoped stock pump.

A hydraulic line with a gage and a valve between the gaged line and the pump can be pressured up to any intrinsic level, the valve closed, pump stopped, and the gage will indicate the pumped pressure in the line, until such time as the valve begins to leak, or is opened.
The scenario you describe is true, but the difference is that your talking about a steel line, which can store energy in the form of pressure because it swells. The head/rotor/plungers are all extremely rigid and cannot do this.

The scenario does apply however to the high pressure lines between the pump and the injectors, which do retain pressure between the injector valve and the Delivery valve/s in the head.

Rpm, pedal angle, Boost pressure, ECT, IAT, all play a part in how long the FS is energized in each constant-beginning variable-ending inj cycle.
Not an easy dynamic to duplicate on a flow-bench, I would think.
But, adjusting transfer pump pressure on the bench could show any advance\retard resulted from higher or lower pressure.
Quite the opposite, as I've tried to explain before, the way the PCM calculates fuel delivery is by a constantly repeating formula. PCM inputs are weighted, and totalled and reduced to an integer value which is the number of Hi Res counts the FSOL will stay energized for. On the test bench you can run manual mode and enter whatever pulse width you want 0-999, and command whatever advance you want 0-10*. Obviously you can also adjust/monitor, transfer/supply pressure as well, and run a draw to check fuel delivery quantity. I wish I could be the one to give you some test bench experience, then you could help me explain all this ;)

Really wish you hadn't said that, because a preponderance of evidence points toward that fact - PCM is strictly a Programmed Fuel Injection, except for the L56 with MAF, and that dynamic is used only for EGR and emissions control.

Boost would be the dynamic, here.
However, when Boost is lost, PCM still dumps fuel at the Boost rate, possibly somewhat less, as "BLACK SMOKE, NO POWER" is always the complaint, which is indicating Programmed FI as the big M.O.

Boost pressure follows fuel rate, obviously, but fuel rate should also reduce as Boost pressure drops in a dynamic system.

And, I think OBD-II handles it no better - they just disguise more of the basic operation to prevent 'hacking'.

Folks, we been rooked - we got a Isuzu PFI system, here.
Where's the glory, in that?

Btw, pumped pressure does not disappear in an enclosed volume, no matter what the rigidity, unless the enclosure or valve leaks.
Flexibility of the enclosure walls only effects the volume of the pressure as it is released.

Even at that, a 100psi increase in transfer pressure would not make as much of an impact on fuel rate, where injection pressure is ~2kpsi, as on increased vane wear.

It was just an excercise in concept.

As long as we can come to an agreement that Transfer pressure, so long as its high enough to fill the pumping plungers, doesnt not affect fuel delivery, I'm happy ;)
Besided, mechanical limits of the transfer pump/head would keep you from going much higher than specifications anyway.
Although the Stanadyne Calibrator does give you the option of a 0-999 input for fuel delivery, the pumps delivery capabilities are not that graduated, rather, it is graduated by the number of hi res ticks on each cylinder, which is considerably less than that.

So the increased fuel pulse from an aftermarket pcm comes from the program calling on the high res to count additionl slots on the encoder disk per injection? I would think that if you could copy your prom you could take shots in the dark , so to speak, till you figured a parameter location or two and edited from there, you could make one work. I'm not set-up for it but I'd like to see it happen.

Something like that, reprogrammers change the limits and the weights of the inputs to get different outputs. But the way I see it, if they can go in and punch in some new numbers and make it work, I can swap in a new cam ring and make it work.

http://www.lli.com/images/logos/atech_logo.gif

GM 6.5L Diesel Injection Pump System - Model 6601


Actual Fuel Injector Pump Operationhttp://www.lli.com/images/products/auto/atech_6601_small.jpg (http://www.lli.com/images/products/auto/atech_6601.jpg)
Variable Control of Injection Timing
Variable Control of Engine Load
Visible Individual Fuel Injector Output
Stanadyne Rotary Injection Pump
Allows for Speeds from 0 to 2500 RPM
Courseware Included
GM 6.5L Diesel ECM System - Model 6611


Injected Fuel Volume Based on Sensor Inputshttp://www.lli.com/images/products/auto/atech_6611_small.jpg (http://www.lli.com/images/products/auto/atech_6611.jpg)
Variable Control of Engine RPM
Variable Control of Engine Load
Variable Control of Engine Coolant Temperature
Variable Control of Engine Air Temperature
Variable Control of Fuel Temperature
Visible Bargraph Display of Fuel Injection Volume
Visible Bargraph Display of Fuel Injection Timing
Performs Pump TDC Adjustment Procedure
Interaction with Standard Scan Tools for DTCs and Engine Parameters
Courseware Included
Would this do it?<!--webbot bot="Include" U-Include="../../contact&copyright.htm" TAG="BODY" startspan -->

Its an aftermarket tester/ECM simulator looks like. Wouldn't work for a calibrator, it would be pretty neat, but I don't see the application for it really.

Nothing to do with programming ECMs that I can see there, just simulating ECM inputs and outputs and tracking what the pump does...I guess you could use it to test a reprogrammed ECM or different IP variations.

FACTS JUST IN!
Both camrings have the same exact lift. Chucked them in the trusty lathe and used my Starrett dial indicator that reads to .0005" (That's tens of thousandths) Both camrings have an exact lift of .028" lift. Guess someone will have to go back and edit a bunch of their posts about camring lift now.

Cam 30501-Mod. DS4-5068 has same lift as a 32096 DS4-5521 & others.

O.K. Mathematicians. Figure this. 4 plungers @ .310" diameter, all four pump exactly .028" lift. Hypothetically how much would it pump out out @ one thousand cycles. This would be the most this pump could hypothetically pump. Need answer in mm/3

Bonus question. The engine runs 3000 rpm at the hypothetical max delivery for ten minutes. How much total fuel will be used in the 6.5?

TDG indicated the 30501 ramps to be more aggressive, which would effect the rate of pressure increase.

A taller ramp would increase the rate and raise the upper pressure limit, being required to occur within the same degrees of shaft rotation to satisfy injection event specs.

Stanadyne apparently thought the HD pump would require the rate increase because of the the narrower injection window in the upper rpm ranges.

I would like to test the 5068 manual transmission eprom in my PCM - get an idea of PCM management for comparison

I have one for auto tranny 4068.

Sincerely 'ppreciate the offer, QM, but it would immediately throw all the 4L80E codes - not a good circumstance for reliable testing, imo..........

Ramp appears to be the same or so darn close it's hard to tell with my equipment.

I would like to test the 5068 manual transmisstion eprom in my PCM - get an idea of PCM management for comparison
I'll save you the trouble, 5521 pump with 5068 PROM will probably not even start without moving the optic sensor, if it does, guarantee you that it will not run very well at all, low power, white smoke and poor idle characteristics no matter what you do to the optic sensor.

5068 pump/cam ring, with 5521 PROM on the other hand, well, I've posted my results from the test bench already, and I'll have results to post tomorrow on how it works on the truck.

And as for you Diesel-Pro, I don't know what it is exactly your trying to prove, but I will assure you that this is a battle you cannot win.

Both camrings appear to be the same. I even checked the cam pin hole with relationship to peak cam lobe lift to see if the cam had a different degree setting between the two. No difference. Changing camrings will not change fuel output, fuel rate, or alter timing. Just the fact, Jack!

So if the cam rings are the same than the difference is in the optical position on the cam and ECM programming? I'd like to try and duplicate tex's output before we condem the idea.

Now Thats An New Idea For Some On Here

Would be a good Idea for someone to try it. Just remember, if you swap a component out the timing must be corrected for each time.

I believe if the 5068 was calibrated to 5521 specs and put in place of the 5521 the engine would probably run just the same. And vice a versa.

Putting the wrong pump on will not work with the optic sensor way off. The 5068 application must have the sensor way over to the side and the 5521 must be almost dead center.

Increasing fuel pressure at low speeds will increase fuel output some. Do not recommend pressure increases at high speed.

Need Optic sensor pics, try here and click on optic sensor on right.

http://www.turbodiesel.no/

The encoder (optic sensor) kinda looks like it's offset just like the 5068 should be.

Increasing fuel pressure at low speeds will increase fuel output some. Do not recommend pressure increases at high speed.Diesel-Pro, you of all people should know that that is simply not true. Furthermore, You can't increase low/midrange pressure without bringing up the top end as well. And you should also know, that above 160lbs puts you in danger of siezing the head. Calibration spec check point @1700 RPM, 50mm(3), 145-157psi, the reason, and you can try this on a test bench as well, is that if you turn the pressure up higher than that, you will notice the pressure jumps rapidly, as the regulator will not be able to return enough fuel to the inlet fast enough to keep pressures down. A plain jane DS pump will make 80psi at idle, and 100 or so at 1500, that's plenty, remeber, you only have to fill .028" of 4 plungers.

The test bench doesn't lie, and I've already tested and observed and posted my results.

A 5068 has higher pressure alright, but the set point is 2000 RPM instead of 1500, and its only 10lbs. Be careful what you claim that I have and haven't tried, cranking up the pressure does not increase delivery one IOTA. Conversely, you can drop pressure by about 40% and not lose any delivery quantity either.
I don't have any ADS Certs, I got mine at 92 Deerfield Rd., ever been there? DS/DE.
I don't know why your trying to turn this into a pissing contest...

In technical circles, TDG, it could be called a debate, particularly if the respondents couch their replys as informational, rather than confrontational.
Opposing technical views broaden the database.

For me, the proof of similar DB2 camring difference was by parallax view across pairs of camrings, indexed by the leading edges of the ramps at the 'valleys'.

With three 0.29" 6.2 IP's and one 0.31" 6.5 turbo IP apart and correlated - columns by rows - by component on my work bench, differences and similarities were easily noted, but for the camrings.

-4911 camring part number had a directional arrow on one side only, indicating CCW rotation only.

Same part number camring from a new '95 6.2 IP had directional arrows on both sides, indicating suitability for CCW and CW rotation.

As I had been advised that the -4911 CW equiv for NavStar was different than the -4911 CCW for GM, I needed to determine the nature of the two identical pn's, for timing and\fuel rate\ rate of increase possibilities.

Did not appear to be much diff by eyeball, but index-comparison revealed I'd better stick with the uni-directional ring for the -4911 rebuild.

I also have a disassembled '97 5288 IP, so when you guys post, I have a reference base.
I do not have a 5068 camring, and I am aware the 5521 will respond badly to the 5068 eprom, but if engine will start and run, an oscilloscope will give me the info I need to determine why\how\what the engineers were attempting with that IP.

At 3500-3700rpm the injection window is narrow, and the IP injection event timing must be altered to fit within that window.
Injection pressure must be achieved quicker than at low rpm, where the window is wide.

If that 5068 camring has more aggressive ramps, meaning same peak height - same pressure - but shorter ramp to peak - faster rate of increase to pressure - , that would indicate mechanical compensation, requiring considerably different numbers in PCM fuel rate\timing matrices for HD IP, compared to LD IP.

Which would result in the specific conditions reported when replacing the 5068 with any other IP, without replacing the 5068 eprom.

If you IP guys can present reliable mechanical data - and I'm not pointing any fingers here, bowtie, so chill out, please - that will satisfy the mechanical aspects.

A 5068 eprom and a 'scope will verify the mechanical and indicate the electronic aspects.

Personally, I'd say scrap all the 5068 pumps, and use a chip designed to deliver appropriate amounts of fuel.

I've had my fill of straightening out mixed up trucks with 5521 pumps in place of 5068 without proper programming.-:t The more of these trucks that are converted, the better IMHO...

You're right, JK, but, as always - I gots to know........

Mine is an ex-5068 with a 5521 now. There was an ecm swap in it's past as well according to dealer records. How would I tell if it's the correct one and wtf do I do if it's not?

OK, got the 30501 cam ring in now...and some mixed results to post about it...

Pulled the pump, swapped the cam ring, and calibrated it. Reinstalled it in the truck, and crossed my fingers. When it first started, it ran terrible and smoked white like crazy. Scanner said idle fuel delivery was 13mm, and the timing was too advanced. So, advanced the optic sensor and retarded the pump housing exactly back to the line I had it at before. Took it around the block a couple times to clear the air out and warm it up. Ran pretty good, I can't say that I was super impressed. Nice puff of black smoke on free rev, tells me that I have successfully increased fuel delivery, as there was none before. Didn't have much more time to play with it, I had already spent almost 4hrs, so I decided it was atleast running well enough to try it for a while. 0-60 I would say is no change whatsoever, engine sounds different for sure, a little bit of clatter under light load, and the exhaust still over powers the engine sound under load. My surge at idle is also gone, and there is no APP surge or any other signs that the PCM is having trouble managing this new config. On the highway is where I noted the biggest difference, tapped the pedal to pass, didn't even kick down like it normally would, stayed in lock up and accelerated smoothly, and still has no trouble pegging the speedo. To put it comparatively, it runs much better than before the optic bump with the old cam ring, and more controlled feeling than after the optic was bumped. The pedal also feels more graduated, very easy to hold any set RPM. I'm starting to wonder if this stinking thing isn't supposed to have a 5068 pump in it! I mean I tested the pump on the bench to follow closely to 5521 specs, and it ran like crap, bumped to the line scribed for a 5068 app, and it runs like a charm??? So I guess at best I could say the 5068 pump definitely still a possibility for H.O. 5521 apps, but too many uncontrolled variables with this being a '94 truck to say it will work for sure.

[QUOTE=gmctd]In technical circles, TDG, it could be called a debate, particularly if the respondents couch their replys as informational, rather than confrontational.
Opposing technical views broaden the database.

If you IP guys can present reliable mechanical data - and I'm not pointing any fingers here, bowtie, so chill out, please - that will satisfy the mechanical aspects.

QUOTE]
Vey good point gmctd

Here's a couple points I forgot to mention, when I calibrated the pump, I set it just a hair more conservatively than the pump I tested first, when I tried it, I discovered it was obviously too far, late timing was making white smoke unbearable, so I had to advance it on the truck to compensate. I also noted, that before I bumped it, L.I. fuel delivery read ~14mm(3), way high, which let me know I had quite a bit of room before idle concerns would limit optic sensor advance. I also tested the pump with a #9 resistor, and since the cam ring IS more aggressive, the resistor had an amplified effect on delivery quantities, easily enough for a combined gain over 10%, though I can't put an exact figure on it because I changed the calibration on the truck.

Overall, the truck runs better I would say, I'm not blown away with the change, but I'm not through tweaking it yet either. The wife is happy the surge is finally cured, and I'm hoping this will improve mileage as well, so I'm definitely keeping it like it is.