effects of fueling characteristics of gov spring

[ellis93]

Since my thinking is horridly screwed on how my governor spring works inside my pump,I need an expert to splan things out to me . I've looked over old treads and seen where adding different gov springs changed how and when the pump fueled and when it decides to cut it. One such tread is
viewtopic.php?f=4&t=9585&start=0&hilit=kta

Notice kta sayes that adding a different gov spring could change fuel characteristics of a pump he was testing,I take it that way....but hey.....maybe I'm just being silly and the understanding is beyond my simple mind.

Now I know that adding other things like a fuel pin CANT add any power to the engine cause its not doing anything but controlling the distance/timing of when/how the pump fuels right? So why do they (advertiser) usually say a 40HP gain?

[Mark Nixon]

From my 1 or 2 experiences with a 3200 spring, I will say that they tend to make changes in the way the throttle arm lines up on the indexes.
I put a 3200 spring in my old flatbed and I couldn't get the fuel screw to add as much fuel at one throttle lever index, and it was adding way too much at another.
Currently it's sitting at the "too much" point with the fuel screw backed out significantly and the idle screw fully removed.

It blows way more smoke than I can stand as it is, but turning the throttle index other way basically has the fuel screw bottomed and power is off, too.
At that point it's just barely above stock with some of the idle screw still showing.

But then again, I think this pump is suffering from a well worn H&R, too.

Mark.

[m880cummins]

I have done 3 governor springs now with no issue. I install them, loosen the jam nut on the idle screw, remove the high speed stop screw and set the throttle indexes to stock configuration, go 1-2 more turns in on the full power screw and take the intake tube off and have a board ready. Never had one run away on a first start up though. Usually, with the stock index, the idle is really high so you have to back the idle screw off 3-4 turns. Once that is done, it drives just like a stock spring until you get about half into the pedal. From there, the pedal is much more touchy especially with boost at that point. Kind of fun if you ask me! I usually put the star wheel all the way down and then back it off about 1.5-2 turns and have the smoke screw out past stock (less smoke) Throttle levers ground for cleareance and banjo bolts drilled makes it really fun. I can with this setup have very little smoke or I can tweak it to a mosquito killer.

Not sure if that answered your question, but keep this in mind too:

An aggressive fuel pin will give you a possible 40hp. That isn't governor related but it's how you set your star wheel and fuel screw. You need to have the air to support it too.A 3200 RPM spring has in my opinion no effect on how it drives unless you get it up in the higher RPMs (2200+). Once past 2200, you just start getting more fuel with less pedal movement.

Spring rates are different because of the wire size they are manufactured out of. Basic physics tells you how to understand this. Spring calculations are as such:

Force of the spring is based on the distance it moves multiplied by the springs constant. The springs constant is the characteristics of the metal, wire size and the number of coils. The force on the spring is the tension created by the throttle shaft moving. The more you hit the go pedal, the longer the spring stretches. As it stretches, the spring will create more resistance. To make it really easy to understand, I will set up a general chart of spring stretch. Note that these are in no way related to specific bosch spring designs but it gets the idea through. The spring equation is F=kx
Force=constant times the stretch length (cm or whatever unit of measure)

"stock"
Stretch lengh(cm) Constant (k) Force applied to governor (F)
1 cm k^2 = 1 (unit ie Newton)
2 cm k^2 = 4 Newtons
3 k^2 = 9 Newtons

Now, a "366" or "3200" spring example
Stretch length (cm) constant(K) Force applied to governor (F)
1cm k^3 = 1 (unit ie Newton)
2cm k^3 = 8 Newtons
3cm k^3 = 27 Newtons

For chits and gigs, a 4000 spring would look like this:

Stretch length (cm) constant (k) Force applied to governor (F)
1cm k^4 = 1 (unit ie Newton)
2cm k^4 = 16 Newtons
3cm k^4 = 81 Newtons


NOW, I am NOT saying your governor spring stretches 3 centimeters or that my (K) value is that of a governor spring. I left K as a variable because I do not know a cummins ve spring constant. I can figure it out easily though. Our governor springs, whether stock, 3200, 3800, 4000 or whatever, are all the same approximate length but the thicker the wire changes their spring constant. It only takes a minute change in spring wire thickness to make a BIG change at the pedal. Notice how all of the first values (1cm) result in the same force at the governor. This is what I am talking about when there's not much difference at lower rpms. The springs all behave the same with minimal stretching length. However, once you get past a certain stretch length, the thicker wire springs will produce a dramatic increase in force. This is why there isn't a more steady increase in fuel CCs when the rpms are increased by the throttle lever. Also, the concept of a governor is factored into this whole concept. The faster the governor spins, the harder it is to keep the weights "tight"=more fueling. This governor force however, is directly related to the speed at which it spins. Governor weight force is a more constant force in relation to RPMS unlike a spring force with distance as I set up.

Set the pump indexing to stock, ignore all I said about springs and crap and back idle off a little and you will be fine.

Charlie

[Mark Nixon]

I tend to disagree with the "Stand there with a board" anxiety, but I turn the pumps up in a different way.
It effectively ends up being the same.

My way is to remove the fuel screw, marking it as best I can for stock settings, then I remove the collar.
I put the fuel screw back in.
I then adjust, by whatever means necessary, the low RPM screw, located on the head side of the pump, so that it has 2 or 3 threads showing, to prevent wear on the casting where the throttle arm will rest.
Rigging a remote starter, with the key on, I crank the engine and run it, then adjust the fuel screw in until I have the idle where it needs to be.
No danger of runaway, no removing the intake, no boards to worry with, no friends necessary.

In the end, this is exactly where the fuel screw ends up, adjustment wise.

BTW, do NOT remove the top of the pump WITHOUT FIRST REMOVING THE FUEL SCREW.
I have a few horror stories on why you shouldn't.

Mark.

[ellis93]

800rpm/idle 7cc
1500rpm wot 180cc
2000rpm wot 200cc
2200rpm wot 200cc
2500rpm wot 190cc
2600rpm wot 180cc
3000rpm wot 45cc
This is just for reference
After about 22/2300 the stock spring starts pulling fuel away from our pumps right? So the 3200rpm spring will keep the cc of fuel there longer,right?

Say you have 410 gears and your running 70mph taching 2400RPMs.....your pump is only throwing 180ccs of fuel to the injectors cause the stock rpm spring has the gov defueling the pump......now you it a hill,big hill,trucks slowing down and you mash the throttle harder.....are you gonna have more fuel the harder you mash the throttle or is it going to stay the same?

Same setup but with a 3200 spring that wont cut fuel till around 27/2800,wish I had found testing for this,and
hit the same hill with your pump still capable of throwing 200ccs of fuel, are you still limited fo 180ccs of fuel?

[m880cummins]

When spinning those rpms, it takes more force for the softer stock spring to be able to close the governor for more fuel and rpms. If you had unlimited throttle travel, the spring could achieve 3200 but it would stretch a lot more before it had the force a 3200 spring could put on the governor. Theres an amateur video on youtube showing a ve pump governor working

[ellis93]

When spinning those rpms, it takes more force for the softer stock spring to be able to close the governor for more fuel and rpms. If you had unlimited throttle travel, the spring could achieve 3200 but it would stretch a lot more before it had the force a 3200 spring could put on the governor. Theres an amateur video on youtube showing a ve pump governor working

So yes it would be capable of throwing more fuel then?

[RCCUMMINS89]

A governor spring does nothing more than hold back the slide collar at a certain point for a fueling purpse.

As rpms increse our governor shaft pushes on the fulcrum lever trying to move the slide collar more and more towards a defueling point.

The stronger the governor spring (the higher the rpm) the more it fights against the governor shaft.



What this means is in stock form at 2400rpms you have to push the throttle down at let's say 3/4 throttle to maintain speed. Because the stock gov. spring is then stretched enough to balance things out. When one installs the 3200 spring, one can maintain the same balance at less throttle...... However, this is all ends in the slide collar being in the same place.

[RCCUMMINS89]

When spinning those rpms, it takes more force for the softer stock spring to be able to close the governor for more fuel and rpms. If you had unlimited throttle travel, the spring could achieve 3200 but it would stretch a lot more before it had the force a 3200 spring could put on the governor. Theres an amateur video on youtube showing a ve pump governor working

So yes it would be capable of throwing more fuel then?

Yes, capable of using more fuel...... only at an rpm though that the stock gov spring can't overcome. Meaning at 1500 rpms the 3200 spring won't deliver more fuel... (well not much).

But once again,you have the capability of moving more fuel...but unless you are speeding up you aren't going to use more fuel.....assuming you could maintain the same rpm as with the stock spring.




Let's put it this way.... switching from a 2 barrel carb to a 4 barrel carb does not decrease fuel efficiency unless you change your driving habits.

[ellis93]

if its capable of throwing more fuel at the same rpm,then what's to say that when you hit a hill that it wouldn't throw more fuel at your motor causing mpg loss over the stock spring that was cutting fuel away.

A 2 barrel carb is steadily leaning out from an idle where as a barrel has two more bores to take up the slack

[RCCUMMINS89]

If you go up the hill at the exact same speed (both gov springs).... you are not using more fuel.


If you accelerate up the hill with the new gov spring and you weren't with the old spring, then obviously you are using more fuel.

It has nothing to do with rich or lean.

[ellis93]

If you go up the hill at the exact same speed (both gov springs).... you are not using more fuel.


If you accelerate up the hill with the new gov spring and you weren't with the old spring, then obviously you are using more fuel.

It has nothing to do with rich or lean.

So your telling me that if I have to push the pedal harder up the same hill with either spring I'm using the same fuel?

[RCCUMMINS89]

With the stock gov spring, you'll need to push on the pedal more to achieve the same amount of fuel than with the 3200 spring.

But, if you are driving up the hill at 65 mph you are burning the same amount of fuel....regardless of gov. spring.

essentially the gov spring changes the relation of how much throttle is needed to product the same amount of fuel.

[Mark Nixon]

Wow, this all reads as being more complicated than it actually is.
Unsubscribing before my head explodes.

Mark.

[ellis93]

So was that a yes or no to my question
I take it as a yes because comparison of pedal position to pedal position (spring to spring) you have more fuel,or the capability of more fuel. There by having more rpm that the pump is pushing fuel?