Rover pump on 1.6TD?

[vanbcguy]

OK you are close!

The governor is purely RPM dependant. It allows the control lever in the pump to move to the full fuel position and then decreases fuel once RPMs pass the max RPM range for that particular governor assembly. There's an idle spring in the governor which provides idle speed regulation and there's an intermediate spring that helps the engine be controllable at part throttle.

In contrast the max fuel screw  adjusts the maximum amount of fuel the pump will provide throughout the RPM range. Any time you floor the pedal below the max RPM speed of the governor the pump puts out max fuel more or less. Basically the max fuel screw adjusts the maximum stroke of the plunger.

Not sure how familiar you are with these pumps, if this isn't new info then feel free to disregard!

There's a control collar around the plunger. As the plunger is pressed in to the head by the cam plate a spill port on the plunger is uncovered as it slides out of the control collar. As soon as the spill port leaves the collar the injection event stops. The entire governor assembly controls the position of the control collar. The max fuel screw moves the "max fuel" position of the collar so that the injector event lasts longer. The further you screw it in, the longer the maximum duration of any given injection event.

At the max RPM for the pump the force from the spinning flyweights in the governor overcomes the tension in the main governor spring. That causes the control collar to move away from the max fuel position. Likewise letting go of the pedal does the same thing. Put the pedal half way down, the control collar will go to half way through the range allowed by the max fuel screw. The engine will accelerate till it hits max RPM or the load on it equals the amount of fuel being injected.

[TylerDurden]

...Basically the max fuel screw adjusts the maximum stroke of the plunger.

Well, plunger stroke is constant... the max position of the control collar is adjusted. The spill port on the plunger is covered until the port clears the control collar. Change the collar max position, max fuel delivery changes.

[TimpanogosSlim]

...Basically the max fuel screw adjusts the maximum stroke of the plunger.

Well, plunger stroke is constant... the max position of the control collar is adjusted. The spill port on the plunger is covered until the port clears the control collar. Change the collar max position, max fuel delivery changes.

Right right. Should have recalled the video better.

Still, it's reducing the total amplitude by clipping, to use a signalling metaphor.

Right?

[TylerDurden]

Hmmm... not sure that clipping is the best comparison, if amplitude is analogous to pressure.

Pulse-width limit might be a better analogy, since the plunger delivers above break pressure during injection until the point in time the spill port is opened.

[vanbcguy]

...Basically the max fuel screw adjusts the maximum stroke of the plunger.

Well, plunger stroke is constant... the max position of the control collar is adjusted. The spill port on the plunger is covered until the port clears the control collar. Change the collar max position, max fuel delivery changes.

Yeah "effective stroke" would have been better wording on my part!

[TimpanogosSlim]

So is the max fuel screw just changing the initial position or maximal / minimal position of the governor?

[vanbcguy]

The fuel screw shifts the entire relationship between the accelerator and the output of the pump - IE if you turn the screw in to increase max fuel, you need to adjust the idle speed afterwards as it will have increased.

[TimpanogosSlim]

The fuel screw shifts the entire relationship between the accelerator and the output of the pump - IE if you turn the screw in to increase max fuel, you need to adjust the idle speed afterwards as it will have increased.

Huh. Can you explain the mechanism?

[8v-of-fury!]

The internal throttle lever has two pivot points essentially. One is the case where it is held by, and then one within it self. So, moving the throttle lever moves the control collar from (figuratively) C to D but moving the max fuel screw takes that same travel and moves it up or down from D to E or B to C.

Its like trying to explain a different language in a few short sentences.. its not really possible. lol

[TimpanogosSlim]

The internal throttle lever has two pivot points essentially. One is the case where it is held by, and then one within it self. So, moving the throttle lever moves the control collar from (figuratively) C to D but moving the max fuel screw takes that same travel and moves it up or down from D to E or B to C.

Its like trying to explain a different language in a few short sentences.. its not really possible. lol

The word you're missing is 'fulcrum' I think.

It sounds like this pump on a 1.6td might be able to be turned down far enough that it's only mildly obnoxiously smoky?

[8v-of-fury!]

Pivot, Fulcrum.. they mean the same thing.

piv·ot  (pvt)
n.
1. A short rod or shaft on which a related part rotates or swings.
2. A person or thing on which something depends or turns; the central or crucial factor.

ful·crum 
n. pl. ful·crums or ful·cra (-kr)
1. The point or support on which a lever pivots.

Any VE pump can be de-tuned for fueling with ease. But when there are guys making more horsepower than you will ever imagine on a 1.6 9mm pump.. Why bother? A better matched pump would be a 1.9AAZ pump or 1.9AAZ internals in a 1.6TD pump.

[TimpanogosSlim]

Pivot, Fulcrum.. they mean the same thing.

piv·ot  (pvt)
n.
1. A short rod or shaft on which a related part rotates or swings.
2. A person or thing on which something depends or turns; the central or crucial factor.

ful·crum 
n. pl. ful·crums or ful·cra (-kr)
1. The point or support on which a lever pivots.

Any VE pump can be de-tuned for fueling with ease. But when there are guys making more horsepower than you will ever imagine on a 1.6 9mm pump.. Why bother? A better matched pump would be a 1.9AAZ pump or 1.9AAZ internals in a 1.6TD pump.

OK, well, when i get the thing here, we'll see if anyone wants to trade.

[8v-of-fury!]

Ohh, you bought it already..... I see I see

[vanbcguy]

There's two parts to fueling - volume and duration. The Rover pump will put out much more volume at the same duration, or the same volume in much less duration.

More fuel over a short duration makes a faster, more violent combustion event which in turn makes more noise since it causes pressure to build in the engine very quickly. Injecting the same volume of fuel over a longer time causes the combustion event to be more gentle and causes the cylinder pressure to build more slowly.

So yes, you can turn the Rover pump down to a level where the total volume of fuel is appropriate but it still won't run as smoothly or as quietly as a proper 9mm pump would. Basically that is why there are different sizes of pump heads in the first place.

[TimpanogosSlim]

Ohh, you bought it already..... I see I see

Would you buy a working 300tdi pump on spec from a reputable source for $115 shipped?

I'm wary of sharing what I've learned about stateside diesel rover parts availability until i get shipping confirmation tho. Found an importer who can probably buy them by the crate and a specialty shop.

There's two parts to fueling - volume and duration. The Rover pump will put out much more volume at the same duration, or the same volume in much less duration.

More fuel over a short duration makes a faster, more violent combustion event which in turn makes more noise since it causes pressure to build in the engine very quickly. Injecting the same volume of fuel over a longer time causes the combustion event to be more gentle and causes the cylinder pressure to build more slowly.

So yes, you can turn the Rover pump down to a level where the total volume of fuel is appropriate but it still won't run as smoothly or as quietly as a proper 9mm pump would. Basically that is why there are different sizes of pump heads in the first place.

OK, it seems like i had to ask a lot of questions to learn that, but thanks.