calling those with tiis and AFM gauges (Bill, Justin, JimG)

[jgerry2002]

Does the pump cut fuel all the way on decel on a Tii?

I dont think its smart enough to know how to "cut" fuel all the way, but i could be wrong.

What I think happens is you end up at throttle profile on the kfish that is matched for lower/rpm idle when you lift the throttle. If you were just accelerating, the motor is cranking along at the higher rpm and pushing a lot more air. This quick "fuel cut" means you end up with more air then fuel and hence the AFR around 18-20 on a quick decel or throttle lift.

[Colin]

Does the pump cut fuel all the way on decel on a Tii?

I dont think its smart enough to know how to "cut" fuel all the way, but i could be wrong.

What I think happens is you end up at throttle profile on the kfish that is matched for lower/rpm idle when you lift the throttle. If you were just accelerating, the motor is cranking along at the higher rpm and pushing a lot more air. This quick "fuel cut" means you end up with more air then fuel and hence the AFR around 18-20 on a quick decel or throttle lift.

That makes sense. I know on most modern F.I. systems the ECU will actually 100% cut fuel under most decel situations (that is how my Megasquirt is setup). I was just thinking it'd be pretty cool if they had that figured out with a mechanical system back then.

[thehackmechanic]

Since KFish is completely mechanical, it has no wide-open-throttle or throttle-closed switches on the throttle body. Idle is just the throttle body resting in whatever stop position the speed screw through the side of the tuna can has been set at. I don't think it's a "state" that the KFish recognizes in any way.

(Similarly, I assume there really is no WOT "state." It's just the throttle open as far as it'll go, which if things are adjusted right, should be all the way open and should correspond with the pump lever in the wide-open "pinned" position. Please correct me if I'm wrong about this.)

Given that, I don't see how it can cut off gas when you take your foot off the throttle.

But I agree with those who say that it's natural for the thing to swing lean when you take your foot off, as the pistons keep sucking in air.

[peteinjp]

Actually the system also responds to rpm as well as throttle position. It is completely possible that the system could cut fuel completely in any instance where rpms are higher than idle with the throttle closed.

Pete

[bnam]

+1

[BillWilliams]

+2

The Kugelfischer is an amazing piece of 40 year old technology.

Ever wonder what that big spring inside the pump is for?

[jgerock]

+2

Ever wonder what that big spring inside the pump is for?

Cuckoo clock perhaps??

I was trying out my mechanics stethoscope last weekend on the tii engine (very sensitive!) and heard the fuel pulsing thru the nylon lines at idle and when the throttle was opened. There was definitely a lag in the fuel delivery.

Also interesting to hear the fuel injectors, the fuel at the pressure relief valve, the air at the intake plenum "logs" and exhaust ports at the manifold. My valvetrain is fairly noisy, even after a careful adjustment of the clearance.

[pilotnbr1]

Any updates? It sounds like you were starting to see some positive results!

[c.d.iesel]

[thehackmechanic]

Last weekend I tweaked the verboten screw in another 1/2 turn, so it's now a mind-boggling 2 1/2 turns from where it was when I bought the car. The AFM now sits right around 14 at wide-open throttle in a range of RPMs and engine loads.

The car runs quite well, but I'd expect a bit more zing at WOT from a '72tii. The PO tells me this car did sit for nearly ten years before he bought it. Compression readings are a little uneven (160 +- 10), and leakdown tests are downright scary, showing about 30% leakdown. The leaks appear to be coming past the rings, not the valves or head or gasket. There is, however, zero blue smoke, even on WOT.

There is also a fair amount of carbon buildup both in the intake manifold (I've cleaned the throttle body) and the pistons (my wife bought me a fiber scope last Christmas -- very useful for this purpose). I've put a bottle of Techron in the tank and am resolved to run it a few hundred miles before I do anything else.

I have a few repairs that are going to take the car down (new Silicon Garage radiator, rebuilding the heater box). At that time I think I'll yank the fuel injectors and send them in to be tested and rebuilt if necessary.

[M3M3]

14 is too lean at WOT. max hp is developed when afr is mid to high 12's.

[BillWilliams]

Rob, may I suggest that you call one of the Dave Redzuses and tell him what you are doing and that you write for the Roundel and get 30 minutes of his time "splaining" the wonders of the Kugelfischer.

Both young and old Dave can give you all the skinny.

If you do, let me know how long into the conversation they mention data logging. They love data.

[thehackmechanic]

I do plan on talking with the Redzusii, but I wanted to get some miles on it and some Techron run through it first.

[williamggruff]

Last weekend I tweaked the verboten screw in another 1/2 turn, so it's now a mind-boggling 2 1/2 turns from where it was when I bought the car. The AFM now sits right around 14 at wide-open throttle in a range of RPMs and engine loads.

I left my spare Kfish at Mark B's house recently, but when I get it back in a fwe weeks, I'll take some measurements and photos to support my babblethon below.

You've seen this before:

Interestingly, the kfish pump guide doesn't mention the relative magnitudes of the two controls acting on the regulating lever inside the pump. Adjusting the travel or position of the warm-up regulator can have a relatively large impact on the level of the regulating lever. See the artistic diagram below.

I bought a spare Kfish in hopes of learning why the Kfish on our Lemons car wasn't delivering enough fuel. I took the top off the spare and poked around at the internals.

The regulating lever is a rectangular plate with 4 holes through which the pump pistons pass. The regulating lever acts as a limiter on the stroke of the Kfish pistons. Pushing the accelerator arm to the wide open throttle position causes the cone inside the Kfish to slide toward the rear of the Kfish, lowering the end of the regulating lever where it contacts the cone by a few millimeters. This allows the pump pistons to move a bit more in their vertical cylinders and gather more fuel. But the few millimeters of vertical motion at the cone equates to a much smaller vertical motion of the regulating lever where it impacts the stroke of the pistons. Rotating the cone (which happens when rpms change) does very little to impact the height of the regulating lever at the pistons, as the cone is pretty close to symmetrical. The combined impact of moving the accelerator arm through its full range of motion, and rotating the cone through the full rpm range impacts the range of motion of the pistons by a few millimeters.

From my crudely scribbled drawing above, you can see that rotating the warm-up regulator eccentric clockwise (viewed from the back of the Kfish, looking toward the front of the car) will lower the regulating lever, allowing the pistons to gather more fuel. Conversely, rotating it counter-clockwise (which is what happens as the car warms up) raises the regulating lever, reducing fuel capture.

Under normal circumstances, the warm-up transmitter grows from flush at start-up to poking out by 10mm at full operating temp. This results in the warm-up regulator arm (and with it, the eccentric hinge) rotating about 45 degrees counter-clockwise (see the red arc in the image below.) This raises the regulating lever about a millimeter, or about half as much travel in the regulating lever as you'd get by going from wide open throttle at high RPM to idling.

The warm-up regulator arm is restricted in its motion by a few things: the length of the verboten screw determines the ultimate limit of counter-clockwise rotation; the hat washer, which moves upward as the car warms up, acts as a secondary limit on counter-clockwise rotation, and; the warm-up transmitter acts as a stop in the clockwise direction. Under normal circumstances, the warm-up regulator arm will only rotate in the clockwise direction if the car is cooling down, at which point the hat washer pulls on the warm-up regulator arm as the warm-up transmitter shrinks back into the body of the warm-up regulator. Of course, if you're trying to richen the mixture, you want the warm-up regulator arm to move clockwise, so you tighten the verboten screw, which in turn pushes against its counter-clockwise stop, which results in a lower limit to the counter-clockwise rotation of the warm-up regulator arm. You could also tighten down on the hat washer to get a similar result. These efforts will produce a static change in the height of the regulating lever at the eccentric hinge once the car gets to operating temperature. Note that neither of these efforts will enable you to make the warm-up regulator rotate clockwise while the car is operating, and the counter-clockwise rotation of the warm-up regulator will be driven entirely by the operating temperature of the car, so you won't have any real control over that process either.

Being the curious type, I wanted to see if the regulating lever would continue to lower, allowing for more fuel capture by the pistons, if I rotated the warm-up regulator arm further in the clockwise direction than the warm-up transmitter would allow. So I removed the warm-up transmitter, and I was able to rotate the warm-up regulator arm through about twice the arc (see the yellow arc as compared with the red arc) as would be allowed in the stock configuration. The resulting change in the level of the fuel regulating lever was dramatic. As noted above, rotating the warm-up regulator arm through its full range of motion under normal conditions results in about half as much change in the height of the regulating lever as the combined change imparted by moving the accelerator arm and rotating the cone through their full ranges of motion. However, if the warm-up regulator arm has full freedom to rotate, it has a greater impact on the height of the regulating lever than the accelerator pedal and RPM combined. The accelerator pedal and RPMs can change move the regulating lever down about 3mm at the pistons, while the warm-up regulator alone can move the lever down about 4mm at the pistons.

For our Lemons racing application, we simply cut the warm-up regulator arm short so that it doesn't impact the warm-up transmitter, and we're able to make absurd adjustments to the mixture my manipulating the position of the warm-up regulator arm. I cobbled together a modified version of the Wes Ingram (Ingraham?) warm-up linkage and found that we can make the car run so rich that it floods and stalls out at middle rpms. Not that you'd want to do that to your car, but you get the point. By connecting the warm-up regulator arm to the accelerator arm with a short section of ball chain (like you'd find on an old hanging light bulb), we're able to cause the warm-up regulator arm to rotate clockwise when we press the accelerator pedal, getting more fuel into the Kfish pistons and avoiding our lean condition.

[BillWilliams]

Nice explanation and drawings there batman.

Now riddle me this Batman, how does the Kugelfischer detect RPMs (engine speed) to regulate or change fuel (backward and forward moment of the cone) mixture that you discuss?