Gas engine tuning for newbies....

[bodofish]

Derrrrrrr...... It's a throttle body.

[SydneyFlyer]

NOTE 1:
A very common problem with cowled in engines is, the air pressure in flight changes the "natural" pressure on the float diaphragm. This causes the engine to run rich in flight. There are several possible fixes available. Most of the time you can simply tune your engine for flight by trial & error. However, the easiest fix is to open up the cowling around the carb area to lower the air pressure. You may also rotate the cover to different positions to see if that works. The "BEST" fix is to solder a piece of brass tubing where the vent is, and route the vent line to a better location. I normally route it into the fuse going through the firewall. It works perfectly every time! Plus, your ground tune doesn't change in flight

Hi Guys this is a post from the very start. Can someone provide me with info on exactly how to solder the brass tube in a walbro carb.

Thanks

[Tired Old Man]

Pretty simple really. Soft lead/tin solder works fine but silver solder works a little better. Need more heat and some flux for the silver solder though.

Remove the cover plate, scuff and clean the area around the hole in the plate, and fit a brass tube to the hole in the plate and solder. You might find a better location to route the tube to will be at the intake venturi to the carb. Just be sure the tube is secured in a manner that remains clear of the choke plate.

This is where some thin flat brass stock and another piece of that brass or copper tubing could come in handy. Make a plate that has a hole to fit where the carb retaining screws passes through the carb. The plate then has to be just long enough to solder some brass tube to that aligns with the edge of the venturi. The other end of the tube has to be long enough and sticking out to where a piece of fuel line can connect it to the tube at the diaphragm opening.

[Tired Old Man]

bodofish,

Just to keep you on your toes, and to better educate me, using a basic throttle body at a standard case intake opening makes an EFI unit different from a simple carb how?

Next, how would it improve performance?

I really am curious to what the answers will be. I'm trying to learn what I can about the possible benefits of EFI for our little engines.

[bodofish]

Sorry, TBI/ECU. The only part missing is the fuel pump (case pressure operated). I did contact them for a client that races karts, who was all over injecting for more power. Not going to happen. No more power unless you want to turbo then EI makes sence but still a pain to set up. I sure never said it would give any performance increase, maybe it was someone else. OEM sales only. They would put me in contact with someone who has bought a few hundred but that is all. And you are exactly right they're nothing more than an electronic carb. Just like most of the early GM/Rochester units. Closed loop system. No O2 sensors and no learning. I'm not sure what you would use to config the ECU but I'm sure if a guy were to buy a few they'd fix ya right up. Don't get me wrong, i'm not advocating heading down the EFI for models path. There is not enough hours in the day to beat my head against the wall getting one to work right, I've done that with cars and boats. As you said earlier weight. The TBI/ECU probably weighs as much as a carb before you add the fuel pump. Walbro is trying to get the small engine green so they can CARB them into CA. They claim easier starting but with a fuel pump powered with case pressure I don't see how. The only point I was trying to make is they are available off the shelf. Do what you will with that. The carb is simple and good!

[Tired Old Man]

I'm with you about the easier starting claim. I think you've figured out I'm fooling with you a little bit I work in small engine R&D. All I'll say is been there, done that.

[RTK]

	Quote: Originally Posted by bodofish
	. Walbro is trying to get the small engine green so they can CARB them into CA. !

Don't worry about small two stroke engines anf fuel injection. In california CARB will (in the near future) ban them, or at least that is the direction they are heading.

[Al Lewis]

	Quote: Originally Posted by SydneyFlyer
	Hi Guys this is a post from the very start. Can someone provide me with info on exactly how to solder the brass tube in a walbro carb. Thanks

You can also try this method. Works great.

http://www.flyinggiants.com/forums/s...35&postcount=6

[Tired Old Man]

I'm in the process of changing my state of residency. If the Californians don't finally get out and change who they have in office and those that had been appointed to various positions you won't even be able to use a horse or mule for transportation or energy purposes. You sure as Hades will not be able to grow anything that requires water because some tiny fish or bug never heard of before might be threatened by the water use. You won't be able to buy motor fuel because none of it will be clean enough in pollutant emissions in spite of all the dirt cheap waste chemicals the fuel manufacturers are required to use in CA at grossly inflated cost structures. If any of those things could still be done you won't be able to afford them because of the back breaking tax rates that increase exponentially with each new social entitlement system thought up by some movie star or film producer aligned with Pelosi and Boxer.

[Al Lewis]

Maybe we could get Hilborn to build a injection system!! I'd love a set of stacks coming out the top of my cowl!! LOL Oh darn, only one cylinder so only one stack. Rather have 4 each side like the old days.LOL

[rcign]

Ever think a 4 stroke would run on propane ?
A customer is sending me a Fuji 25 four stroke to ignitionize...He has it running on propane...His test plane is an old Nosen trainer, currently using a 120 glow engine...Stay tuned...and don't say it can't be done, it's running...
I don't know anything else, wait until it gets here next week....

[jamesrxx951]

	Quote: Originally Posted by rcign
	Ever think a 4 stroke would run on propane ? A customer is sending me a Fuji 25 four stroke to ignitionize...He has it running on propane...His test plane is an old Nosen trainer, currently using a 120 glow engine...Stay tuned...and don't say it can't be done, it's running... I don't know anything else, wait until it gets here next week....

i dont see why it couldn't run on propane. forklifts have been for years. curious to see it on a airplane engine though.

[Al Lewis]

Should run fine if lubrication is not an issue. Typically they get a little less power on propane. Seems it would make the plane heavy depending on what he's storing the propane in on the plane.

[Tired Old Man]

All an engine needs to run, unless a diesel, is gas, oxygen, and spark. I already know they will run on various fuels. 3w and others have had heavy fuel (JP-5) engines out for quite some time. I can't understand the reason for a compressed gas fueling system in an airplane.

[bodofish]

	Quote: Originally Posted by rcign
	Ever think a 4 stroke would run on propane ? A customer is sending me a Fuji 25 four stroke to ignitionize...He has it running on propane...His test plane is an old Nosen trainer, currently using a 120 glow engine...Stay tuned...and don't say it can't be done, it's running... I don't know anything else, wait until it gets here next week....

In the late 70s a buddy of mine had a propane powered AMX drag car. It ran right around 10.5. Propane is 110 octane or so I've been told.