Hi Ed,

 

The original valves supplied by Van’s are a tapered plug valve with brass on brass sliding surfaces.  Sliding surfaces of identical metal composition have a tendency to gall and seize.  Lubricating with fuel lube ore something similar helps for awhile but doesn’t seem to be a reliable solution to the problem.  Several years ago, those valves have been superseded by valves of the same design but with delrin  plastic inserts that eliminate the metal to metal sliding contact.  I had two of these valves and they always worked well.  In the end, the fuel system I have now doesn’t require these valves and I gave them to my hangar mate who replaced his original sticky valve with one of the newer ones and he hasn’t had any problems since.

 

The new valves can be purchased from Van’s or ACS for about the same price as the old ones.

 

It doesn’t seem to me that fuel of any kind between the sliding surfaces for lubrication would be a good thing since then the valve would be leaking.

 

Steve Boese 

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Monday, October 20, 2008 7:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Water in Fuel?? (or another adventure in the aviation events of Ed Anderson)

 

I agree, John.  Several folks I mentioned it to at the Rotary Round up thought that the 2 cycle oil in the gas would do the job.  But, I would estimate that the force required to turn the handle had nearly doubled – to the point I was thinking about where I kept my lock-jaw pliers.  I don’t use MM, but that might help.  I must admit that I couldn’t help thinking that if it did not lubricate the ball valve – was the 2 cycle oil doing anything inside the combustion chamber.  Then I remembered that its there as much to cool as lubricate the seals.

 

Perhaps some of the guys with a background in chemistry could tell us why 100LL appears to lubricate a brass ball but 2 cycle oil does not appear to.  Are hydrocarbon molecules much larger than lead Pb molecules and unable  to fit in the tight tolerance of the ball value??

 

Ed

 

 

----- Original Message -----

From: Ed Anderson

To: Rotary motors in aircraft

Sent: Monday, October 20, 2008 8:43 PM

Subject: [FlyRotary] Re: Water in Fuel?? (or another adventure in the aviation events of Ed Anderson)

 

John, I think your analysis makes lots of sense for a gravity fed fuel system (i.e. no pumps).  However, I would think that the EFI pumps would churn the water and fuel together pretty thoroughly.  Although, the difference in specific gravity and viscosity of water and gasoline may well cause one to behave differently in flow in such a system.

 

In any case, I did use some auto gas back a couple of flights ago and did not like it.  The engine had a bit of a miss – nothing bad, but just noticeable – could have been the plugs needing a change to be fair.  I also found out that the lead in the 100LL does do one beneficial thing – the fuel selector used in the RV is a brass ball type.  The lead apparently keeps it lubricated and it turns easily.  I noticed after running about 10 gallons of auto gas that it started to take considerably more force to turn it.  Now that I have run a number of gallons of leaded gasoline through it, it is back being easy to turn.

 

However, after paying $5.40 /gallon for 100LL on this trip, I may way find myself swayed to the “dark side” {:>)

 

Ed

 

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.dmack.net/mazda/index.html

---

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of John Downing
Sent: Monday, October 20, 2008 8:39 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Water in Fuel?? (or another adventure in the aviation events of Ed Anderson)

 

Al, as the water is heavier than the fuel, the water droplets will normally travel along the bottom of the hose or tubing, dropping out at the first low location.  Some turkey stole the gas out of the Piper Colt one time and a 4 inch layer of snow without the cap left a bit of water drops laying around on the bottom of the tank, two cans of dry-gas took care of the condition.  Now if we can get Ed to burn auto fuel, the alcohol will absorb the water and any left over after a sump drain check will go thru unnoticed.  JohnD 

----- Original Message -----

From: Al Gietzen

To: Rotary motors in aircraft

Sent: Monday, October 20, 2008 4:40 PM

Subject: [FlyRotary] Re: Water in Fuel?? (or another adventure in the aviation events of Ed Anderson)

 

In my design, the primary injectors are first in the fuel rail loop with

both secondary injectors following then the pressure regulator.  So perhaps

the primary injectors were injecting a high ratio of fuel/water whereas by

the time the slug got to the secondaries it was mostly water?

 

Wait, turning the cold start on OR turning either injector pair off

(secondary in my incident) both result in the same effect of doubling the

pulse duration.  Any time you turn an injector  pair off you also ground

(turn on) the cold start circuit (right Tracy???).

 

Cold start doubles the pulse to all 4 injectors; turning off one set doubles the pulse to the remaining two.

 

I was guessing maybe the secondary were maybe first in line; but the reality is there is no way of telling where the water was going to go first, or how much in each, or whatever.

 

Al

 

So turning the secondary injectors off probably simply provide the same

effect (for whatever reason) as turning on the cold start.

 

In my "incident" several years ago, I was able to keep the engine running

approx 30-45 seconds longer with the cold switch on than with it off.

Sometimes 30-45 seconds longer engine run might make a difference.

 

In any case, checking fuel for water goes back to getting the emphasis it

deserves.

 

Ed

 

Ed Anderson

 

Rv-6A N494BW Rotary Powered

 

Matthews, NC

 

eanderson@carolina.rr.com

 

http://www.andersonee.com

 

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

 

http://www.dmack.net/mazda/index.html

 

 

-----Original Message-----

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On

Behalf Of Dale Rogers

Sent: Monday, October 20, 2008 11:40 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: Water in Fuel?? (or another adventure in the

aviation events of Ed Anderson)

 

Bob Mears <bmears9413@aol.com> wrote:

> I actually a little surprised it had that much stumble. I would think

> with the fuel injection and a re circulating system it would just pass

> the water through the system and slowly burn it off. I guess it was a

> fair amount of water and thats all that was going through the system

> at the time. Like a quart of so in the bottom of the tank. That would

> take a bit to pass through. Interesting.

 

That depends on how much fuel can be held in a branch that has no outlet

other than the injector.  If the runs off the main path are short, then

the effect should be short lived (but pucker-factor is measured in very

long, individual, nano-seconds).

 

Dale R.

 

 

 

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