REFLECTOR:GAMInjectors
Chuck Jensen
reflector@tvbf.org
Sun, 27 Jul 2003 10:54:23 -0400
Soctt,
If you have instrumentation for temp readout of each cylinder (mine is
VM-1000) you really ought to do the "lean test" shown in GAMI's web site:
http://www.gami.com/frames.htm. Even with an autopilot, you really should
have a second person along to look-see while you have your head buried in
the panel. Just start ROP, reduce fuel flow 0.2 to 0.4 each set of EGT and
CHT readings across the cylinder. GAMI has a printable spreadsheet for this
on their site.
As I mentioned in my earlier post, I was pretty surprised how pathetic my
spread was at 2.1 gph, when a good spread is 0.5 or less. If you're already
running smooth LOP, my guess is your spread is markedly less. I know when I
tried LOP operations, I'd get that "rough" feeling. It wasn't blatant, in
that you couldn't see it in any instrument, but is was a "feel".
The only problem I had was when installing the injectors (and thank you
Jean, for excellent pop-off access holes through the cooling plenum), the
fuel connection threads on the injector for #1 cylinder stripped. I haven't
figured out why because there was easy access and I'm 99.9% sure it wasn't
cross-threaded but just as it started to snug up, it went slack again.
Inspecting the injector threads, the tops of the threads were pretty well
gone. I reinstalled the original in #1 and it went back in just fine,
including the fuel line fitting. All the other injectors installed without
glitch. So, I'm mystified as to what happened but its a sick feeling. I'll
post what GAMI does about it (see if they will help correct what must have
been my mistake).
I'm intending to get a couple good set of readings from my OSH trip and will
post them back to GAMI. Based on those readings, they may fine tune the
injectors by changing out one or more (no cost except shipping during first
year) to get to the best balance. I looks like they must have 5 or 6
different size injectors.
In sum, I started out pretty skeptical but am coming around to believing
they may actually be on to something. But, I've been fooled before...often
as a matter of fact!
Full disclosure: I have no interest or relationship with GAMI and have
never done anything with them other than to enrich their treasury. I
understand there is another company out there doing something of the same
ilk, though I don't have a name.
Chuck
-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Scott Derrick
Sent: Saturday, July 26, 2003 11:15 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Low fuel light
Chuck,
Let us know how the Gami's work out. I'm lucky that my IO360 will run
50 to 75 LOP now that I have the EI installed. I wonder how much better
things would be if I caughed up the dough for a set of Gami's.
Scott
Chuck Jensen wrote:
> Brett,
>
> I suspect the point is, why did the air get into the sump or how logical
> is it that air is actually in the sump or, if that is not logical, then
> it does point to a faulty instrument. An investigation tree might look
> like:
>
> Air in sump:
> 1. From the either tank?
> No, both tanks were full and fuel outlets were always
> covered
> 2. From the vent line?
> No, the sump vent line is open and there is no source
> for the line to be pressurized to blow air into sump
> 3. Did the sump become starved for fuel from the tanks and pull
> air in through the vent?
> No, flow paths open and if it was that starved, the
> engine would have stopped.
> 4. Was air in the sump all the time and just hadn't been vented off
> No, the vent to the sump was always open and air should
> have been displaced by gravity flow of fuel.
> 5. Do we know for sure that there is air in the sump?
> No, we only infer that because we are getting the low
> fuel signal.
> 6. Is it logical that air is actually in the sump?
> No, not if it is vented off and there is not pathway or
> mechanism for air getting into the sump
> 7. If air in the sump is not the problem, then what is?
> Then, it would seem to be a faulty instrument (float
> only semi-buoyant) or a faulty signal.
>
> and so on. Of course, if any of the answers in the question-path are
> wrong or different than we think, then that limb breaks off the tree.
>
> I don't mean to insult anyone's intelligence because this is pretty
> simple stuff. I've found difficult problems can be simple to solve with
> a structured approach and simple problems can be difficult to solve with
> a shotgun approach. I've used both!
>
> With that said, I'm still working on the unbalanced tank draw-down
> problem. I have a long trip scheduled next week, so I'll be able to
> test the theory that I'm unbalanced (which comes as no surprise to a lot
> of people) and that I need to shim the rudder slightly.
>
> I just installed a new set of GAMInjectors this morning so I'm looking
> to get some good "lean test" numbers to see if the balance has
> improved. I was confident that my engine was "pretty good" in that area
> because it does run smooth. NOT. There was 2.1 gph difference between
> peak EGT across my cylinders as I leaned out. 1.0 gph is OK, 0.7 is
> acceptable and and <0.5 is an excellent target. That's probably why the
> 540 started to run rough in the LOP region. In sum, mine numbers were
> kind of pathetic side.
>
> The single gph or two that are saved will probably never recover the
> cost of the injectors but if running cooler and smoother increases TBO a
> hundred or two hours, now we're talking real money. And, like many
> things, it feels good for it to be right!
>
> Gotta go. Have some OSH flight planning to do.
>
> Chuck
>
>
>
> min@tvbf.org [mailto:reflector-admin@tvbf.org]On Behalf Of Brett Ferrell
> Sent: Saturday, July 26, 2003 9:06 AM
> To: reflector@tvbf.org
> Subject: Re: REFLECTOR:Low fuel light
>
> Why would you jump to the assumption it's air in the tank? Without
> a sightglass, or replacing that run of tubing to the sump neoprene
> or something, we don't have any idea what's causing the indication.
> Could just as easily be a defect inside the instrument. My whole
> contention was that, if air is entering the sump, it's probably for
> the best b/c the alternative is most likely to pull a vacuum on the
> tank. Air doesn't displace fuel without a reason.
>
> Brett
>
>
> ----- Original Message -----
> From: alventures <mailto:alventures@msn.com>
> To: reflector@tvbf.org <mailto:reflector@tvbf.org>
> Sent: Friday, July 25, 2003 5:56 PM
> Subject: RE: REFLECTOR:Low fuel light
>
> Al,
>
>
>
> This thread started with Rene's problem with occasional low-fuel
> warning with plenty of fuel on board. How is the air getting
> into the sump tank if the strake tanks have enough fuel to keep
> the strake-to-sump fuel lines submerged? The sump vent seems
> the most likely route.
>
>
>
> Keith
>
>
>
> Yes, I agree with that; assuming of, course, that the
> intermittent warning is due to a low level in the sump tank
> and not a problem with the float switch, or something else.
>
>
>
> After giving the issue more thought, the valve in the sump
> vent seems to make sense. Although it is one more thing on
> the checklist, and not convenient to get at. And it doesn't
> preclude fuel exhaustion in the case of a leaky fuel cap.
> If we are going to keep a simple gravity feed system from
> both tanks, we have to pay attention to the fuel caps, and
> be aware of one tank level dropping faster than the other.
>
>
>
> Let's see; if we could just find a different place to put
> the fuel cap; someplace that doesn't happen to see about the
> maximum negative pressure of anywhere on the airplane.
>
>
>
> Al
>
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