fuel filter puzzle

[Dean Pappas]

Hi Earl, and Hi All,
Since I've run pressure fed YSes since '81, with the exception of the suction fed OPS rear-intake in '86 and the early OS-61LSes in '87, I haven't had the problem you mention with an RC ship.

The O.S.61 LS and the 140 RX both share the "Perry-pumped" characteristic of tolerating bottom-end leaness with a small quit-an-catch or POP on throttleup. What Matt says is correct.

On Control-Line ships, we learned that a large air filter like the crap-trap can hold quite a slug of air, if it is oriented just the wrong way. If the input end of the filter is toward the inside of the circle, then a bubble can form there like a backward bathroom sink trap. This bubble usually broke loose at positive to negative "G" transitions or some other horsepower critical spot. As a result, in CL we use a small volume filter (the hard to find,  screw together HR unit is nice) and we orient the filter front-to-back, so as not to create a "trap" shape. I've never seen this in RC, though. 

Do you have room between the pump and firewall for a small filter or for the crap trap lined up with the fuse? This is science!

Say hello for me and the family,
	Dean

-----Original Message-----
From: Brian Young [mailto:b4598070 at yahoo.com]
Sent: Wednesday, March 26, 2003 9:25 AM
To: discussion at nsrca.org
Subject: Re: fuel filter puzzle


Earl, Ive had the same problem. Usually a hesitation
coming out of a long idle, especially on inverted
stuff, you think it has died and then it pops and
goes. Sometimes blows a cool smoke ring.

What Matt said is correct, needle setting. You really
want the filter before the pump cause stuff in the
pump is bad. Maybe by moving the filter ahead of the
pump you dropped your pressure slightly more than
having the filter between pump and carb, thus leaning
the engine a bit more.

--- Rcmaster199 at aol.com wrote:
> In a message dated 3/25/2003 10:19:39 PM Eastern
> Standard Time, 
> jivey61 at msn.com writes:
> 
> 
> > Subj:Re: fuel filter puzzle 
> > Date:3/25/2003 10:19:39 PM Eastern Standard Time
> > From:<A
> HREF="mailto:jivey61 at msn.com">jivey61 at msn.com</A>
> > Reply-to:<A
>
HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> > To:<A
>
HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> > Sent from the Internet 
> > 
> > 
> > 
> >  Earl
> >  I just last weekend started using my Webra 145,
> and noticed a hesitation 
> > when I throttle up. My filter is also before the
> pump. This may be the 
> > problem. I was thinking it may be a little rich on
> low end. I have 2 
> > gallons fuel run through it now.15%.
> >  
> > Jim Ivey
> > 
> 
> Jim,
> 
> If you are running the pipe at the recommended
> length, then what you are 
> describing is a lean idle needle. You may want to
> richen it a lttle at a time 
> until the problem is eliminated.
> 
> Also if you decide to run higher nitro than what you
> are using now, you 
> wantto richen the idle needle.
> 
> To prove it to yourself, I suggest that you run a
> tankful that is about 5% 
> less nitro than what you are using now, and see. 
> 
> Matt Kebabjian
> 


=====
Brian Young
Tulsa
b4598070 at yahoo.com
918-745-6046h
918-838-0900w

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