Do you periodically clean your Carb. screen, or just wait until it clogs up, and then clean it ?

> Jim

Jim- I run a felt clunk, the kind used in chainsaws, etc. and I haven't had to clean a clogged screen in years. Believe it or not your vent line will suck in debre depending on your runway. I also run a paper filter on my gas can out line. The only time I clean the screen is when I have to replace parts on the carb, (and it always seem clean enough) or the engine was not running right because I did not use a felt type clunk.

Yes.



Periodically, I'll clean it, and usually after it has clogged with something, but not so much (never, actually) since I went to using a lawn mower filter in the fuel jug, then an inline filter (Madison products, not a "screen" - ) in the fill line inside the plane.

Dual filtering has taken care of all issues for me.

From experience, I'd advise that you check it periodically. How do I know?

Well...I was flying my 1/4 Fokker Dr.1 with a Zenoah G-38 at the Danville, VA giant scale fly-in several years ago. The engine, which had run perfectly for two years, began to sputter on acelleration and didn't want to idle well. Like a moron, I ignored these warning signs and taxiied out for takeoff anyway. I made the takeoff rollout and lifted off the ASPHALT runway. About 10 feet in the air, the engine said, "I quit", and did. Now, 10 feet of altitude at just-over-flying speed isn't enough to save a Dr.1 when the engine gets real quiet. The resulting crash sent it back to the shop for a month while I built a new top wing, rebuilt half of the middle wing, and fabricated another set of cabane struts. It also ended my flying on the second flight of the first day of a two-day event. [:@]

The autopsy found a clogged carb filter screen. A $5 rebuild kit got the engine running perfectly again.

Now, I filter my gas three times. Once in the supply can, once at the supply filling barb, and once in the onboard gas tank klunk. I NEVER let the ends of the lines touch the ground, and I listen real careful to what the engine is telling me. I also check and replace the carb filter screens about every 25 flights.

Dr.1

I like periodic preventive maintenance, so yes, I do.

I run the fuel through a filter as it is loaded. I DO NOT use an on-board filter. I was using felt filters, but found that the felt fibers break loose with time and clog the screen in the carb. I had this happen, but caught it on the ground. I clean them by-annually as part of my under-the-cowl preventive maintenance routine. Never find much.

After a few engine failures: When that little mesh filter gets clogged, the dirt in it compacts so fast that you hardly have time to react to the symptoms

I run a felt filter in the tank kneaded in petrol and flushed well before fitting. This filters so well, that the screen in the carb stays clean.
I use a three line tank. One for filling (with fuel dot), one to the carb, and one vent line.
My filler bottle has a paper filter on the outgoing line. Better would be to have that filter in the fill line inside the plane.
When mixing fuel, the fuel is strained through a funnel filter.

I filter the fuel twice before it gets to the carb. Once coming out of the can and once in the tank. A Walbro felt clunk is used at both locations. Periodically I clean the carb screens just in case, but since switching to the felt clunks a few years ago it has proven to be unneccessary....so far. if you filter the gas before it gets to the carb the felt klunk in the tank is good for a couple hundred hours of running time. The one in the can gets replaced more often and as needed.

Those little felt clunks seem to remove every drop of fuel without bubbles too.

Yes, they do.
In my 4-banger spit I had tank foaming problems and the engine would quit often. A fourstroke is less tolerant of fuel line bubbles than a two stroke. After fitting a felt clunk, running became absolutely reliable.
It works like this:
The felt sucks up all fuel it comes into contact with by capillary action, and spreads evenly all around the felt, so no air is prsent anymore. So as long as there is a fuel puddle, or fuel spray/foam/(younameit) it will replenish the fuel used up by the engine. When the tank is completely empty, air can break through that fuel barrier, and the engine very suddenly stops. There will be hardly any warning or lean runs.

edit-PS
In whinemaking, I used to use this kind of filter to get the last bit of that precious fluid out of the fermenting jug without disturbing the lees. I stopped this hobby some ten years ago, because it tended to get out of hand

Always wanted to try my hand at wine making. I used to brew beer, that was loads of fun. Kids, family and business put an end to that[] And yes things can get out of hand

My fuel is filtered three times before it reaches the carb. One felt filter in my gas jug pick-up, a paper element filter in the fill line from my manual hand pump, and an in-tank felt filtered clunk on the carb's feed.

Early on I used an inferior quality felt filtered clunk in the tank and paid the penalty of having some of it's fibers clog the carb's screen. Since then I do take an occassional look see but since switching to using a premium quality felt filter the screen has remained quite clean.

Karol

Though a bit off the beaten track, what do you guys use at the end of your exposed vent line to stop dirt and debris from entering the tank.

Karol

I usually don't use anything. In the past I have used a vent line filter, but I can't remember where I bough it.

I don't do anything to the vent line. Since it is always a bit wet with oil not one single dust particle will make it to the tank inside, where the felt clunk would take care of it anyway. When I fill up, and the ventline overflows, it is clean again. I have never seen it to be dirty on the inside though.
I normally do nut fill up the tank that much, but sometimes it happens. When it does, it flushes any trapped particles in the line.

That's a nice simple solution .... thanks Pe.

Karol

Thank god, you are American and I am Dutch. If we were to be both English, and beerbrewer vs winemaker, we could not be on speaking terms anymore. []
It's a crazy world we live in.

What Walbro filter are you people using, and where can they be purchased?

Greg

I would try any lawn/saw shop. They should have the good ones.

Do you have a model or part #?

Greg

Sorry no, but they are pretty good sized and they have a clasp over the end that holds the felt on.

This may help out.

Warbird Lover

Over here the Tillotson felts are popular, they have no clamp.

Thanks guys for posting the pictures, that helps a lot.

Greg

You can get those vent filters at Dons Hobby Shop,,,,,He has a great line of products ,,plus they have a line for anyone to call for problems. Don is very knowledgable on all gas criteria.----TAZZZZ