I know that one of you fellows posted the bosch part number for a high speed governor spring for the VE pump.<br><br>I have just spent the past twenty minutes in the search section here looking for that post, and I just can't find it -- it is driving me crazy!<br><br>Can anyone out there help?<br><br>Thanks,<br><br>Alec

Aslitch, I posted the part numbers sometime back.<br><br>The spring part number is Bosch# 1464650366 <br><br>It is a 3200 governer spring that allows your pump to add fuel up to 3000 rpm instead of starting to defuel at around 2700. This spring is used in the Marine VE pump applications, stationary engines and also on the high performance VE pumps. They are not very high and cost under 40 bucks.<br><br>HOWEVER, I had talked to Piers about fueling over 3k. He plainly stated that our pumps would not handle spinning in excess of 3k. Although, jughead and some others have put this spring on there 1st gens with the auto tranny with very good results. This is not the only spring out there, in fact, the VW Rabbit diesel used the same pump as ours, as well as many Land Rover units. Springs varying from 2k to 5k is very common when searching for one. Just be careful and dont use the springs FULL potential.

OBR- where does the spring go on/in the pump?

Jbolt,

Here (http://www.cs.rochester.edu/u/jag/vw/engine/fi/injpump.html) is a link to a non aneriod AFC boost head VE pump. You can see that the governer spring connects to the control lever and the tension lever. Now, if you look at your pump where the aneroid AFC head mounts on top of the pump, you will se 3 allen head screws around the pump. Most of them have yellow paint on the allen head. You take this top cover off to gain access to the spring.

Okie- I've been trying to grasp how all the internal mechanical parts work in these things. The picture in the link really doesn't help. I take it the govener spring pulls on the control lever which inturn closes off more of the spill ports as the throttle is increased? I'm not sure what the tensioning lever and flyweight are for.<br><br>While We are on the subject. Where does the AFC fit into the fuel chain? I'm trying to put together the relationship between the AFC and full power screw.<br><br>Any idea where one could get ahold of a tech manual for the VE pump?<br><br>Thanks,<br><br>Jay

Well...I tried to help. Lets see, where to start.<br><br>Unlike Delphi, Lucas or Stanadyne pumps. The rollers on the VE pump are not actuated by an internal cam ring with lobes on it, but instead the cam ring circular and attached to a round cam plate. As the cam ring rotates with the injection pump driveshaft and plunger, the rollers (which are fixed), cause the cam lobe to lift every 60* in a six cylinder engine. In other words, the rollers do not lift on the cam as in a conventional system, but it is the cam ring that is solidly attached to the rotating plunger that actually lifts as each lobe comes into contact with each positioned roller spaced apart in relation to the number of engine cylinders. With such a system then, the plunger stroke will remain constant regardless of engine rpm. At the end of each plunger stroke, a spring ensures a return of the cam ring to its former position. Therefore, the back and forth motion of the single pumping plunger is positive.<br><br>The sequence of events in a VE pump. The fill slot of the roatating plunger is aligned with the fill port, which is recieving fuel at transfer pump psi as high as 7 bar (100psi), one cylinder only. <br><br>The rotating plunger has reached the port closing position. The pluger rotates a control spool regulating collar. The position of the regulating collar is controlled by the driver though linkage connected to and through the governer spring and flyweights. Therfore, even though the roller may be causing the cam ring plunger to lift, the position of the regulating collar determines the amount of travel of the plunger or prestroke, so the actua effective stroke of the plunger is determined at all times by the collar position. <br><br>As the poiint of plunger lift (start of effective stroke), fuel delivery to the hydraulic head and injector line will begin in the engine firing order sequence.<br><br>The effective stroke is always less than the total plunger stroke. As the plunger moves through the regulating collar, it uncovers a spill port, opening of the high pressure circuit and allowing the remaining fuel to spill into the interior of the injection pump housing. This then is port opening or spill, which ends the effective stroke of the plunger<br><br>With the sudden decrease in fuel delivery psi, the spring within the injector nozzle rapidly seats the needle valve, stopping injection and preventing after-dribble, unburned fuel, therefore engine exhaust smoke. As the same time, the delivery valve for that nozzle located in the hydraulic head is snapped back on its seat by spring psi.<br><br><br>More to come ;D<br><br><br><br><br><br><br>

One thing to always remember is that the force of the governor spring is always attempting to increase the fuel delivery rate to the engine, hile the centrifugal force of the governor flyweights is always attempting to decrease the fuel to the engine. Anytime that the centrifugal force of the rotating governor flyweights and the governor spring forces are equal, the governor is said to be in a state of balance and the engine will run at a fixed steady spead. <br><br>Engine acceleration:<br><br>When the throttle initially beyond the idle range, the weights will compress the idle spring and the weight force will now act upon the force of the intermediate spring for a short time. This spring allows a reasonably wide idle speed range, a large speed droop, and a soft or gradual transition from the low idle speed range (governor control) to the pooint where the driver has complete control over the engine speed. The intermediate spring will be completely compressed shortly after the engine is accelerated from idle, and the throttle pedal now acts directly through the linkage to the sliding sleeve. There is not enough weight force to act upon the high speed spring until the engine speed approaches the high end. Engine speed is now directly controlled by the driver.<br><br>High speed control:<br><br>When the engine speed and therefore governor weight force is great enough, the centrifugal force of the weights will oppose the high speed spring until a state of balance occurs. When the weights and spring come into play at the higher speed range, the maximum speed of the engine is limited by the fact that the weights as they fly out cause the sliding sleeve to transfer motion through lever and which will compress the spring and therefore move the control spool to its left to shorten the effective stroke of the pump plunger. In this way, the engine recieves less fuel and the masimum speed of the engine is therefore limited when the weights and spring are in a state of balance. <br><br>The aneroid boost head compensator control:<br><br>Basically, the boost compensator ensures that the amount of injected fuel is in direct proportion to the quantity of air within the engine cylinder to sustain correct combustion of the fuel and therefore increase the hp of the engine. With the engine running, pressurized air from the cold end of the turbo passes through the connecting tube from the engine air manifold to the boost compensator chamber. Inside this chamber is a diapraghm which is connected to a pushrod (eccentric cone) which is in turn to coupled to the pin. Movenment of the diapraghm is opposed by a spring, therefore for any movement to take place at the pin, the air psi on the the diaphraghm must be higher than spring tension. As the engine RPM and load increase and the air psi within the connecting tube becomes high enough to overcome the tension of the spring, the diaphragm and pushrod will be pushed down. This movement causes the compensator pin come in. Forcing the fuel contol rack toward an increased fuel position. The boost compenstor will react to the engine inlet air psi regardless of the action of the governor. When the turbo boost reaches its maximum, the quantity of additional fuel is injected will be equal to the stroke fo the aneroid boost compensator pin, in additon to the normal full load injection amount that is determined by the governor full load stop bolt.<br><br>Clear as mud? Good ;D<br><br> Monty

Monty, That was awesome! !!!<br><br>I'm going to print this, grab a big cup of coffee and read it about 500 times and see if anything sinks in. ;D [eyecrazy]<br><br>I'll be back<br><br>Jay

Monty-<br><br>Earlier you stated Piers said the pump would not handle over 3k. Is this due to the strength of the plunger return spring?<br><br>In the “Engine Acceleration” paragraph you use the term “Intermediate Spring” Which one is that on the picture in the link you posted? <br><br>In the picture it is hard to tell if the governor lever pivots or slides. I’m guessing pivots but the picture makes little sense in this area. It is hard to see how the full power screw works. I’m guessing the full power screw either increases the range of the “effective stroke” or ????<br><br>The 3k spring is then a stiffer spring to counter the flyweight and therefore increase the “effective stroke” of the control sleeve? Changing the spring has the same effect as adjusting the high idle screw but without increasing the control lever movement?<br><br>You say the “compensator pin” in the AFC moves the “fuel control rack” Is this the governor lever assembly or? So movement of the compensator pin changes the effective stroke?<br><br>How am I doing so far?<br><br>Jay<br>

As I recall a similar conversation with Piers on this topic, he felt that the work/trouble to do the spring kit idea was more than it was worth. He felt that using the high idle method was pretty much, just a effective, and a 5 minute job in comparison. I have done the latter method, and now pull right up to 3000 RPM no problem.

FWIW.... bob.

BTW, Monty,.. awesome post... can I grab that for the benefit of other 1st Genners elsewhere or is it to be left here only??? either way, fantastic info/post... you get a 5 RWHP bonus for that one bud....:):)

bob.

<br>As I recall a similar conversation with Piers on this topic, he felt that the work/trouble to do the spring kit idea was more than it was worth. He felt that using the high idle method was pretty much, just a effective, and a 5 minute job in comparison. I have done the latter method, and now pull right up to 3000 RPM no problem.<br><br>FWIW.... bob.<br><br>BTW, Monty,.. awesome post... can I grab that for the benefit of other 1st Genners elsewhere or is it to be left here only??? either way, fantastic info/post... you get a 5 RWHP bonus for that one bud....:):)<br><br>bob.<br><br><br>Sure Bob, BTW...I have quite a few different pics of the VE pumps workings. I will try and scan them off and put them here in my photo section very soon.

Not so fast Bob, I'm not done with him yet. ;D ;D ;D

Engine Acceleration revised:<br><br>When the engine is accelerated beyond the idle rpm, the centrifugal force of the roatating governor flyweights will force the sliding sleeve to the right and with the starting lever up against the tensioning lever, the idle spring will be compressed. Additional engine speed and weight force will now cause lever to pul against the larger governor spring. Movement of the throttle lever causes the engine speed control lever to move away from the idle speed adjusting screw and toward the full load screw. The travel of the speed control lever is determined by the driver and just how fast he or she wants to go ;D. When the driver stops on the throttle, the previous state of balance condition that existed at idle is upset in favor of the gov spring. The control spool is moved through the starting lever and the tensioning lever so that the effective stroke of the rotating pump plunger is lengthened by moving the control spool initially to its right. As the engine recieves more fuel and accelerates, the centrifugal force of the rotating flyweights will push the sliding sleeve to its right causing the starting lever and the tensioning lever to stretch the governor spring. When a state of balance condition exists once again between the rotating weights and the spring, the engine will run at a steady speed with the throttle in a fixed position. If the throttle is placed in full fuel, the speed control lever will butt up against the full load adjusting screw, which will limit the maximum speed of the engine. Weight force at this point is greater than the spring force, therefore, the sliding sleeve will cause the starting and tensioning lever to PIVOT around the support pin. The control spool will be moved to the left which will reduce effective stroke of the rotating pump plunger. As a result, the engine will recieve less fuel, therby automatically limiting the maximum speed of the engine. When the centrifugal force of the rotating governor flyweights are exual to the governor spring force the engine will run at a fixed RPM at max speed. If the engine was started and accelerated to its max rpm with the vehicle in a stationary position, the action of the governor weights would limit the maximum amount of fuel that the engine could recieve by moving the contol spool to decrease the pump plungers effective stroke. When the engine is running under such a condition (max no load speed) it is no recieving full fuel.<br><br>The reaction of the governor when a load is applied to the engine will always be the same at any speed setting.<br>Description:<br>Load applied at a given speed setting of the throttle, and engine slows down such as when going up a hill.<br><br>Upsets state of balance between weights and governor spring when above idle speed, if at idle, spring in favor of the spring force.<br><br>Spring pressure is greater and therfore the starting and tension lever move the the control spring to its right to lengthen the effective stroke of the rotating pump plunger and supply the engine with more fuel to develop additional HP.<br><br>If the load on the engine continues to increase, the engine will recieve more fuel to try to offset the load, but is will run at a slower RPM.<br><br>As long as the engine can produce enough additional hp, the governor will once again reach a state of balance between the weights and the spring, but at a slower speed than before the load was applied.<br><br>When the load was applied, the spring expanded (lengthened) to increase the fuel to the engine and ins so doing lost some of its compression; therefore the weights do not have to increase their speed/force to what existed before to establish a new state of balance. The engine will produce more hp with more fuel but will be running at a slower RPM.<br><br>Regardless of the governors reaction to increase fuel to the engine, if the load requirements exceed the power capability of the engine, the rpm will continue to drop. In our trucks, the only way that the speed can now be increased is for the driver to select a lower gear by downshifting.<br><br>If the engine was running at an idle rpm and an the air conditioner pump was turned on, the engine would tend to slow down (load increase). the governor through the spring force/less weight force would increase the fuel to the engine to prevent from stalling.<br><br>Engine Decrease:<br><br>Engine speed decreases, weights fly out with more forced and they will cause the sliding sleeve to move the starting and tensioning levers against the force of the spring.<br><br>The control spool will move to its left to decrease (shorten) the effective stroke of the pump plunger and reducde fuel to the engine until a new corrected state of balance condition exists.<br><br>With load on the engine, it requires less hp and less fuel and as the engine slows down, so do the weights until the state ob balance is reestablishied.<br><br>If a vehicle goes down a hill, the load is reduced. If the driver does not check the speed of the truck, it is possible for the driving wheels to run faster than the engine. IF the drive wheels starte to rotate the engine, the governor weights will also gain speed and by doing this, they will reduce the effective stroke of the pump plunger and the engines fuel will automatically be reduced.

Monty, :o You have way too much time on your hands. ;D

[laugh] Mark, thats my problem, I have NO time, and when I get time I dont know what to do with it [eyecrazy] [laugh]

Monty- you’ve outdone yourself. Many thanks for your effort. It is GREATLY appreciated.<br><br>If I may continue. Taking your brilliant description of the fueling governor how does the AFC tie in? <br><br>Ultimately where I’m going with this is a better understanding of cause and effect from “tweaking” the pump and the pumps limitation.<br><br>Example 1: I have been told that turning up the full power screw effects the lower to middle throttle range more than the top end. Why?<br><br>Example 2: My stock AFC was set up for an engine to make 160 hp @ 2500rpm, max boost somewhere between 13-15 psi, timing around 1.25mm, stock injectors &amp; turbo. From the wear markings on my eccentric pin (factory set at about 20%)I know it has used the full amount of travel at the stock boost levels. With the Lucas injectors, timed at 1.35mm I was making 26psi. I recently set the eccentric to 70%, timed to 1.5mm and I’m only making 22psi but with more power.<br><br>Jay<br><br><br>

I sent this in an e-mail to a fellow who was looking at modifying his AFC. It refers to the pictures from the Bosch VE manual (which can be purchased on-line as a .pdf document from SAE for ~$15). I am guessing from the discussion on this thread that you all might find it interesting, despite its length.<br><br>. . . but I will re-hash my analysis of the pump operation here. (The figures in the manual on pages 22 (Fig. 1)and 37 (Fig. 7) will be helpful for the following discussion).<br><br>There are two adjustments that control the maximum fuel delivered by the pump. The first is the &quot;Full-load adjusting screw&quot; (Fig 7 # 10). It can also be seen in the upper right on Fig. 1 pg. 22. As far as I can tell, it rotates a static lever (fig 7 #11) around a fixed fulcrum. The top of the lever rides on the adjusting screw and the bottom has the fulcrum for the <br>&quot;tensioning lever&quot; (Fig. 7 # 12, but more plainly visible in fig 1).<br>Adjusting the &quot;power screw&quot; moves the fulcrum for the tensioning lever back and forth, and the position of the tensioning lever controls the slip collar on the piston, which controls when the piston spill ports open (ending fuel delivery for that stroke). Turning the screw in moves the tensioning lever fulcrum to the right (as pictured), and thus the slip collar to the right. This is why over-adjustment of the full-load screw results in high idle, and eventually erratic governor operation. The second adjustment is through the AFC. The AFC assembly controls the &quot;Reverse lever&quot; (Fig 7 #3) which acts as an adjustable stop for the travel of the &quot;tensioning lever&quot;. (the following references are to fig. 7) As pressure increases on #14 #8 moves down, letting #4 slide to the right, #3 rotate clockwise, and # 12, the tensioning lever, move further to the left (as pictured).<br><br>By changing the orientation of the &quot;Sliding pin's&quot; &quot;control cone&quot; you can change how far out into the AFC bore the &quot;guide pin&quot; extends, and thus the stop position for the tensioning lever. The further out the &quot;guide pin&quot; is allowed to extend into the bore, the more fuel you get. On my pump, I observed that with the &quot;sliding pin&quot; removed, the &quot;guide pin&quot;<br>would extend out farther into the bore than even the narrowest part of the sliding pin would allow, and that the pump would operate properly with the guide pin extended this far. Running the pump with the &quot;control cone&quot; set in the maximum fuel position, I find that I produce too much smoke at manifold pressures under about 3psi.<br><br>So, ideally I would have a &quot;control cone&quot; with a taper that started from no detent, and continued to a detent that was as deep as the guide pin will extend (with the sliding pin out, and the accelerator floored -- can be measured with motor not running).<br><br>I am not sure how much manifold pressure is required to cleanly burn all of the fuel delivered by a fully extended guide pin, but I would guess that it is at least around 10 psi. I know that once I get about 3psi of manifold pressure my smoke goes away. This makes me think that the AFC needs to<br>operate over a wider pressure range. The amount of travel possible for the sliding pin is limited by the flexibility of the diaphragm and the design of the AFC housing. So we can't<br>just make the pin slide further. However, if we had a steeper angle on the control cone, and a stiffer spring, then a specific pressure would result in less movement of the sliding pin, but the same movement of the &quot;guide pin&quot;, and the same fuel delivery for that pressure. Overall, it would allow for a<br>wider pressure range to have an effect on fuel delivery, with the same travel of the &quot;sliding pin&quot;.<br><br>I measured the spring constant of my spring, using a ruler and a scale. I cannot remember what I figured it to be, however, I remember deciding that the maximum travel of the sliding pin took place over a change in pressure of about 6psi, and that about .125&quot; preload would give me a starting point of about 2-3psi. so my max fuel would come in around 8-9psi. So -- my idea was to measure the maximum extension of the &quot;guide pin&quot; and the maximum travel I could get out of the &quot;sliding pin&quot; then cut a notch in a new piece of stock that was linear and ran from the outside edge of the stock to the depth that equal the &quot;guide pin's&quot; maximum extension. The notch would also have to be in the right place, obviously, and I thought<br>that using two nuts (one on each side of the diaphragm) might allow for fine adjustment. Then I thought that I could jam little rubber blocks into the stock spring, starting at the ends, until it was stiff enough so that maximum fuel would only be delivered with sufficiently high manifold pressure (that pressure to be determined by trial and error). <br>

<br>As I recall a similar conversation with Piers on this topic, he felt that the work/trouble to do the spring kit idea was more than it was worth. He felt that using the high idle method was pretty much, just a effective, and a 5 minute job in comparison. I have done the latter method, and now pull right up to 3000 RPM no problem.<br><br>What do you mean by the high idle method? I need to run at least 3000 rpm do to low gearing. What is the best way to achive this goal?<br><br>Thanks Neil<br>

Neil,

You can increase the top end RPM by using what is called the
&quot;high idle screw&quot;.
It is located on the fender side of the pump, just under the domed AFC housing. It will have a stubborn tamper cap on it (if it has not been touched yet) that you need to remove.

I'd cycle the throttle open/closed a few times and watch the throttle lever motion. You'll see that at rest, one end will have a stop plate that contacts the normal idle screw end. At WOT the opposite (high idle) screw will be contacted by a stop plate on the throttle. It MUST make contact with the high idle screw when at WOT. If not, you won't get full RPM's.

Once the tamper cover is off, you'll see a long screw, just like the normal idle screw. This will have 2 locknuts on it, both are 10mm I believe.
Mark the screw somehow, and loosen both locknuts off. Once they are cracked loose, turn the screw out (counter clockwise when viewed from the firewall end) about 3 turns.
Tighten locknuts and test drive.
You may need to repeat a number of times depending on where it is now, and how sensitive the pump is.
Each test drive can be done in 1st gear WOT. Watch the tach, you'll feel the engine start to &quot;fall off&quot;, then, it will contiue to gain RPM much more slowly till it peaks and will go no further. That is your top end RPM, and the point were it falls off is your defuel point.
Right now, my truck will pull right up to about 2900, and creep to 3000 RPM.
Some do this test in &quot;N&quot; or &quot;P&quot; in the driveway (on auto's) but I personally like to have atleast some load on the engine when I run it up like that. Either way should work.

I've attached a pic to show you the layout. The correct one is labelled &quot;governor screw&quot;.

I wanted to say thanks to Monty and asilitch for their controbutions to this thread. <br><br>Great Job guys!

;D i have the utmost respect for piers, but i have to disagree with him on the 3000 governor spring. i tried the high idle method first. it would pull to 2900 plus but not very strong above 2650. the 3000 governor spring will make the engine as responsive as a gasser at low rpm and pull like crazy to 3000 plus. i would never go back. it is more than worth the effort to change. just to brag a little if you can believe the new diesel pickup 1/4 mile slips my 13 year old ctd will drive around all 3 brands of show room pickups. ps i cant touch nascar mark period.

Jughead,

If I read your post correctly, you're saying that the high idle allows you to pull up to 2950'ish, but that you feel a definite &quot;defueling&quot; prior to that??? Did I get that correct??
That is in contrast to the spring change which shows no sign of defueling until ???? when?? . This spring change has allowed you to have a governed speed of roughly 3000 RPM without 'high idle' adjustment???

BTW, what did the spring cost you, and how long was your install time?
I'm a bit concerned over this particular mod. The reason I say this is because, in recent reading up on the VE, there are some extremely close and interdependent tolerances inside. The cam ring, rollers, piston, idle arm lever, and more are extremely interconnected. Don't take this the wrong way, I probably need to dig a bit more into the workings but it seems that changing one item like that spring can effect other stuff like the governor counter weights and more. Thoughts???


Bob.

I have to concurr with Jughead. I have the same experience with the high idle method. I can still feel it defueling at about 2600. Where do I buy the spring?

I am like Bob on this one. To me, a higher tensioned spring would make the flyweights extend further out to create a state of balance with the gov. spring and flyweight at high fueling points (WOT etc.) thus, putting more stress on the flyweights and possibly making them run out. I dunno, im on the fence as well with this one. :(

<br>Jughead,<br><br>If I read your post correctly, you're saying that the high idle allows you to pull up to 2950'ish, but that you feel a definite &quot;defueling&quot; prior to that??? Did I get that correct??<br>That is in contrast to the spring change which shows no sign of defueling until ???? when?? . This spring change has allowed you to have a governed speed of roughly 3000 RPM without 'high idle' adjustment???<br>the governor spring made the truck come alive. it pulls to 3000 plus that is where i chicken out. it has been in there a year 10k mi. plus. 12 passes at strip. one missed gear. went to neutral from 2nd. dont know where tach went. dont know enough about pump to know what is happening just know it works great. good bad or ugly i love it.<br>BTW, what did the spring cost you, and how long was your install time?<br>I'm a bit concerned over this particular mod. The reason I say this is because, in recent reading up on the VE, there are some extremely close and interdependent tolerances inside. The cam ring, rollers, piston, idle arm lever, and more are extremely interconnected. Don't take this the wrong way, I probably need to dig a bit more into the workings but it seems that changing one item like that spring can effect other stuff like the governor counter weights and more. Thoughts???<br><br><br>Bob.<br>

<br>Jughead,<br><br>If I read your post correctly, you're saying that the high idle allows you to pull up to 2950'ish, but that you feel a definite &quot;defueling&quot; prior to that??? Did I get that correct??<br>That is in contrast to the spring change which shows no sign of defueling until ???? when?? . This spring change has allowed you to have a governed speed of roughly 3000 RPM without 'high idle' adjustment???<br>i cant seem to get my posts in the right order. my reply is in the middle of my previous post. on puters on a scale of 1 to 10 i am less than 0. sorry about the mix up.

Well, the spring vs. high idle method deserves a bit more investigation....
I have had the chance to do some reading, fairly in depth, since Okie's posts on the VE. I didn't realize just how complex and interdependant the internals were on this pump. Simple as it seems, it's not.
Once again, please don't take me wrong here guys... I'm just now coming to get a bare glimmer of a grasp on things like Okie mentioned such as 'state of balance' etc. Other things like RPM Droop.... ok, don't go there...:)
There are a couple things that I've come across that definitely warrant more investigation for performance reasons...now I just add the spring change to the list....

bob.

Changing the spring does not change the range of motion of the governor weights. (Though adjusting the AFC eccentric does).<br><br>For any given speed, there is a specific amount of centripital force required to keep the flyweights from spreading. This force is supplied by the &quot;tensioning spring&quot;. If there is not sufficent resistence in the spring, the weights spread and push the governor rod forward, moving the slip collar to allow less fuel delivery AND pushing the &quot;tensioning lever&quot; against the &quot;tensioning spring&quot; -- if there is not sufficient resistance in the spring, the tensioning lever will hit a stop on its pivot, and no fuel will be delivered by the pump.<br><br>If the spring tension is greater than the force of the rotating weights, then the tensioning lever will move until it hits the stop controlled by the AFC, and maximum fuel will be delivered.<br><br>The only thing that is changed by changing the stiffness of the spring, is the relative engine speed and accelerator positions that define these two events (no fuel and max fuel). No fueling and maximum fueling can happen at any engine speed.<br><br>Changing the spring does nothing but change the speed range over which the maximum governed speed can be set. All of the parts inside the pump move the same amount, etc.<br><br>As far as droop goes: If the system worked perfectly, then letting off on the accelerator a hair would immediately cause fuel delivery to be completely shut off for a moment until the engine slowed down, and vice versa, which would allow absolute full fuel to flow until the engine hit a specified RPM range (equalling a specific spring tension) and then no fuel at higer RPM's. The reality of spring technology and other intentional modifications for drivability, is that the governor tends to cut the fuel off a little bit gradually with increasing RPMs before it cuts it off completely -- spring constants aren't linear, and the range of motion between no fuel and full fuel is material . . .<br><br>That all said, one spec of dirt can be enough to ruin an open pump, which I find to be an important consideration in open pump surgery.

This is some great info. With my &quot;defueling point&quot; set at 2950-3000rpm, I can see the boost start to slowly fall off before then. This is consistent with my last dyno sheet that showed my max hp at 2420rpm. It will still pull up to the governor fairly strong, but slows about 2420 rpm when the boost starts to drop. So, I actually start to defuel there, and not at 3000rpm. This isn't as noticeable after the hybrid turbo upgrade. I guess it just masked the condition.<br><br>Mike<br>

Another thought - The P7100 has a high idle adjustment, right? If so, why are the GSK's so popular, and not adjusting the high idle screw? <br><br>Mike<br>

Good question Smokey. I have often wondered that too. I think a guy would be alright to run the bigger RPM spring in the VE pump as long as he had the high idle set to 2900-3000 RPM. But, if you can put a larger spring kit and not mess with the high idle on the P Pump. Then that blows that theory clean out the door. ???

;D it is a shame you guys are so far away from soddy- daisy , tenn. i believe just the low end throttle response would convince you the spring is worth it. ps dont want anyone to hurt their truck ,but 3 ? years of the spring hasnt hurt mine. about 30k mi.