Cheap & Easy conversion muffler smoke injector
 

Hi,

I've used various means to make smoke oil injectors in my homemade mufflers for my conversion engines, but I think I've found the cheapest and easiest method now.

Just go to the hardware store and buy a 1/8" pipe thread by 1/8" compression tube brass fitting. While you are there, pick up some 1/8" copper tubing and some extra 1/8" compression ferrules or sleeves. If your hardware store doesn't carry these things, any auto store will have them.

First drill the fitting all the way through with a 1/8" drill bit so the tubing can go through the fitting instead of entering a small amount and stopping as is normal. Then drill a hole in the muffler in an appropriate place, and screw in the fitting. I then silver soldered mine, but JB Weld would hold it fine as well. Then insert a piece of 1/8" tubing of an appropriate length, and lock it down with the ferrule and nut. I locate the end of my tubing (injector) in the middle of the exhaust stream near the exhaust entrance in the muffler, and I flatten the tube slightly to disperse flow somewhat, and angle the tube slightly away from the exhaust port.

I used to buy "fuel barbs" to solder to my tubing to prevent the hoses from slipping off, but I now use the 1/8" tubing ferrules. Much cheaper!!

Pics tell the story....

AV8TOR

RE: Cheap & Easy conversion muffler smoke injector
 

I've heard gassers do not need a coil in the muffler, would this work on a gas/glow conversion?

RE: Cheap & Easy conversion muffler smoke injector
 

I don't use coils in mine and they smoke just fine, including my Gas/Glow engines. I was flying my Giant Stik with it's Poulan 42cc on Gas/Glow the other day and it was very overcast/murky out. The smoke showed up well even in those poor conditions. The muffler shown is one of two off of my 48cc twin cylinder Gas/Glow engine.

There are two schools of thought on coils in the muffler. One says to use them, and the other says that the coils cool the exhaust and don't help. Like I said, I don't use coils and have good results.

AV8TOR

RE: Cheap & Easy conversion muffler smoke injector
 

How to get also the Oil there in a cheap manner, i.e. without using a pump, I was thinking to use pressure from the crank-case. Do you think it would work well ?

RE: Cheap & Easy conversion muffler smoke injector
 

Congratulations. I like the idea. Have you run these modified mufflers to test the silver solder and JB Weld?

Still remember standing watching silver solder drip off a gasser muffler modification and land Very close to a bare topped foot, (sandals full time)!

RE: Cheap & Easy conversion muffler smoke injector
 

Yeah, thanks for bringing that up Mike. You CAN NOT use the standard Sta-Brite silver solder on mufflers. It WILL melt. You have to use "real" silver solder with a high silver content, or silver braze. They are available through welding shops or online through McMaster Car.

I have many mufflers running that were made, or modified using the good silver solder with no problems. I also have some that I sealed up the seams where the mufflers are clinched together with JB Weld and it works well also. (No drips on the sandals; worn full time here too!) ;)

AV8TOR

RE: Cheap & Easy conversion muffler smoke injector
 

NikolayTT

You can use crankcase pressure and a one way valve to pressurize a smoke oil tank to deliver the oil to the muffler. Make really sure the tank and hoses are secure, as they will be under pressure all the time and a leak or rupture will make a hell of a mess! I use a Mikuni impulse fuel pump on my systems. I believe you can find them at motorcycle shops. They are the same pumps used in the B & B smoke systems. I did buy a cool adjustable electric pump that will be operated by the radio for my 29% Extra project however....

The pics don't show the shutoff valve. I've used the cheaper Dubro pinch valves with success, but I'm now using a better valve made by Perry. Note also that the pump comes with fittings for 1/4" tubing, which I removed or modified for use with 1/8" tubing.

I've also made little impulse pumps by sawing off the fuel pump part of a old Walbro carb. It can be done and does work. You just have to trace out the passages and block some off and add fittings in the right places.... I'm sorry but I don't have pics of this process to better explain....

AV8TOR

RE: Cheap & Easy conversion muffler smoke injector
 

Thanks Av8tor ! That saves me good deal of time for messy experiements. I am adding also home-made
low-cost check-valves from fuel filters, made by adding inside a ball from ball-bearings and a spring from
a ball pen; so far I have used them only on the fuel line for glow-engines.

RE: Cheap & Easy conversion muffler smoke injector
 

I've heard that this pump works well, and it's sure cheap enough: http://www.jcwhitney.com/webapp/wcs/...atalogId=10101

It's 12 volts, so to save weight I would use a 3 cell LiPoly battery pack. You could rig up a microswitch on the throttle setup somewhere. I would break the pump in by running it for a good while on low voltage to let the brushes seat in so that they won't spark during use and cause radio interference. Just the same I would mount it as far away as possible from the radio equipment.

Lot's of ways to do it.....

Have fun,
AV8TOR

RE: Cheap & Easy conversion muffler smoke injector
 

Thanks, that is really cheap compared to Tower hobbies list.

RE: Cheap & Easy conversion muffler smoke injector
 

AV8TOR,

Those washer pumps work well. I have one [link=http://www.rcuniverse.com/forum/m_3354569/tm.htm]in my USS[/link]. It is the plane you see in my avatar, and the pump is powered by a 4.8V 600 mAh NiCad pack.

Later,
Omaha