Brian Builds the Kerzel Hit and Miss I.C.

[gbritnell]

Brian,
Any spark plug will suffer from flooding. The trick is to get the carb adjusted to where it's not running too rich. When raw gas burns slowly it makes carbon. Carbon is a conductor. When the plug is coated with carbon the spark just follows the easiest path to ground an thus very little or no spark.
Clean up your plug, start the engine until it's a little warm and then start adjusting the carb towards the lean side until the rpm goes down or it falters and then back it out a minute amount. With that setting it shouldn't be flooding the cylinder.
gbritnell

 

[Brian Rupnow]

GBritnell---I am slowly going about the process of eliminating any potential cause for my engine not to run as good as many I have seen on this forum. I KNOW that all of the major mechanical components are good, because there are physical tests to verify the facts. My rings and valve seals are good---I have good compression. My bearings are good---it doesn't rattle or pound and its not difficult to turn over. The coil, points, and condenser are good---pull the coil wire and turn the engine over by hand, and when the points open it will crackle out a blue/white spark 1/2" long. I built a second carburetor to try it with yesterday. There was marginal improvement, but not enough to say that all my problems are solved. By changing/replacing components one at a time, I hope to isolate whatever problem there is. I may be a novice machinist, but I am certainly not a novice mechanic. I have read a great deal about the making of home built sparkplugs, and its a fact---they do wick both moisture and fuel up between the corian and the outer shell and will misfire internally--and intermitantly. I have experienced "no fire" conditions enough times now (I have been test running this engine daily for over a week) to suspect the sparkplug. And the meerest hint of suspicion is grounds enough to change or replace the part at this stage of the game.

 

[Brian Rupnow]

And here's your laugh of the day---I have been doing all my Kerzel testing using the very small gas tank that I have on the Webster engine. A couple of times when it absolutely refused to start, a check of everything found that it had ran out of gas and I was unaware of it. After my great success yesterday with soft solder, and urgently needing a larger fuel tank, I took the fitting I had made to pressure test the cylinder, drilled a hole in the side of the only metal can I had available with a screw on top, and with the addition of a bit of soft solder-- Voila'---instant large fuel tank.

 

[rudydubya]

Brian, I've been following your discussion with Rick about carburetors over on his build thread. I'm no expert on any sort of engine, but I'm wondering why you're not getting enough vacuum to get fuel into your engine unless you raise the tank. My tank is located below my carburetor, with the very top of the tank itself about 1/4" below the level of the needle valve (picture below). For a cold engine, I usually choke it by putting my finger over the bottom end of the carb and turning the flywheel over once or twice. I can see the fuel in the fuel line rise up to the carb inlet as I do that, and there will be fuel on my finger when I finish. The fuel line stays full while it's running, and will actually stay full for several minutes after I shut the engine off (I assume by capillary action). One other thing I didn't mention is the fuel line I'm using. I got it at the local auto supply store, the guy behind the counter said it was used for weed whacker engines. It's inner diameter is less than 1/8" (actually 3/32" I think, a 3/32" drill bit slip fits nicely), but it stretches enough for a nice tight fit over the 1/8" OD carb inlet. I'm wondering why not more vacuum in the fuel line with that simple carburetor. Looks just like mine. scratch.gif

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Regards,
Rudy

 

[gbritnell]

Hi Brian,
I have to echo what Rudy said. Any of these engines should pull enough vacuum to get the fuel to the carb, at least .25 below the needle valve level. Possibly the flooding problem that you're experiencing is because the fuel coming from your can has a 'head' to it and is over feeding the carb. Try making just a simple little container for the time being and put it near the carb.
gbritnell

 

[Peter.]

From my days of building RC model aircraft, I recall the optimum height for the fuel tank is such that the fuel is level with the needle when the tank is half full.

 

[Brian Rupnow]

I did a bit more testing last night. There is a lot of conflicting information available. Many people have been telling me that the tank must be ABOVE the carburetor. My little Upshur style carb will lift fuel about 2" just purely based on venturi effect. It could be that my inconsistent engine running has been a result of the engine flooding out because of the fact that my fuel tank has been above the carburetor. I ordered a new Rimfire sparkplug last night, and once I have it here and a proper adapter made, testing will resume.---Thanks Guys

 

[Metal Butcher]

I did a bit more testing last night. There is a lot of conflicting information available. Many people have been telling me that the tank must be ABOVE the carburetor. My little Upshur style carb will lift fuel about 2" just purely based on venturi effect. It could be that my inconsistent engine running has been a result of the engine flooding out because of the fact that my fuel tank has been above the carburetor. I ordered a new Rimfire sparkplug last night, and once I have it here and a proper adapter made, testing will resume.---Thanks Guys

Brian, I'm not sure why anyone would suggest ("conflicting information") that a simple carburetor, like the one used on the Kerzel engine uses should be gravity fed. Maybe their thinking in terms of carburetors that are gravity fed into a fuel bowl. On those once the fuel reaches a certain level a float pushes up on a needle that seats to cut off the addition of any more fuel. With out this 'cut off' the engine is guaranteed to flood and run erratically, and to even shut off do to a shorted (wet or carbon covered) spark plug.

I would set the tank up with its highest possible fuel level (fully filled), a 1/2" below or slightly less (.450"- .500") than the center-line of the needle valve and jet. If the engine won't draw fuel with that level, then you need to make a new carburetor. Raising the fuel level to compensate for a carburetor with a defective draw is not the correct approach to solving the problem.

-MB

 

[cfellows]

MB is right on. If you put the fuel tank above the carburetor, all the fuel will drain out through the carb.

Chuck

 

[Brian Rupnow]

My education continues. I am only beginning, after 3 years to know the people who truly know what they are talking about, and be able to seperate them from the people who don't know but still rush to offer up "constructive advice". The trouble with any public forum, is that there are always a number of well intentioned folks, who have no idea if what they are telling you is correct, or if is what they surmise, or what they heard somewhere, but they have never actually lived the experience themselves. These people are not generally deliberately obstructive. but they want so badly to "help" that they offer up whatever comes into their head. And although I have a reasonably good BS detector, there are many times when I truly don't know, and so I am somewhat at the mercy of those who give questionable advise. Of course, this isn't particular to the internet. If I went to a small engine building club in person and asked 25 people for advice, 5 of them would decline to answer because they truly didn't know. 5 would give great advice, based on their own personal experience, 5 would tell me what they heard a friend did", 5 would make something up just because they didn't want to be left out, and 5 would misunderstand the question so badly they would just stand there with a glazed look in there eyes!!! ;D ;D ;D

 

[bearcar1]

What you say is true Brian, but then of course there are always those that will not listen to good sound advice for whatever reason(s) and go wandering aimlessly into the night much like Don Quixote, tilting at windmills, certain that they are correct in there quest and when they find the error of their ways, it is dismissed as folly and the cycle continues on. It is extremely hard for me to merely dismiss anyones suggestions when I do not know how to rectify a problem, sure it gets frustrating at times but to call someone a fool for attempting to help is a true sign of arrogance onto itself. Better to be humble and say "no thank-you" than to assume that someone else doesn't know what they are talking about. Just saying.

BC1
Jim

 

[Brian Rupnow]

Jim, I've been accused of many things in 64 years, but never of being humble. I've been wrong before, and probably will be again, but I do try not to advise people of things which I know less of than they do.

 

[stevehuckss396]

Hi Brian.

I set the height of my gas cap at the height of the inlet fitting/needle so that even if I over fill, the fuel level will never be higher than the needle. My tank is 1-1/2 inches deep and the carb will suck it dry.

I guess what i'm saying is to set the tank as high as you can without the fuel level reaching the level of the needle.

Works great!!

 

[Brian Rupnow]

Thanks Steven---Is that a Model A I spy in the background?

 

[Brian Rupnow]

Ya never get too old to be kinda dumb!!! I have known for quite a few years now that fluids tend to run down hill. I've known that these small carbs don't have a float bowl, nor a check valve. What was I thinking????----I want a new brain for Christmas!!!!!

 

[stevehuckss396]

Look at it this way Brian. There are thousands of variables when it comes to model engine building. sizes, tolerances, materials, timing and on and on. So you had a brain fart and screwed one up. An easy one to fix at that. Think of all the bad things that could have happened and all you got wrong was something this easy to fix. I would say you have a perfectly fine brain to get you this far. You should be proud of what you have done.

And yes that is a model A

 

[steamer]

....ditto.

Now worries Brian....you need a brain to do what you've done..

And oh by the way...I know a lot of people a damn site smarter than I that couldn't begin to do what you've already done!

Dave

 

[bearcar1]

I wasn't accusing you of being humble.

BC1
Jim

 

[gbritnell]

Brian,

I have been following this thread since day one and have, like others, offered my best advice on building an IC engine. Upon rereading one of your previous posts I see that you edited it and rightly so. In the time that I have been a member I have found that most everyone gives advice from what they have learned, some have just learned more than others.

As Steve so succinctly stated, IC engine building involves so much more than steam/air construction, compression, spark, timing, tolerances etc. and to a beginner it can be truly overwhelming. It's easy to throw up one's hands and say I've had enough but to see a project through takes real perseverance.

I think you have done a very good job on your first IC build. The information you have learned can now be passed along to someone else starting out. That's how the system is supposed to work.

You can chill out now and have a Labatts on me.
George

 

[Peter.]

Another thing just occurred to me Brian. Traditional castor-based fuel used in model aircraft is quite heavy and oily as a fuel with a good surface tension. It's quite possible to have the fuel level above the needle somewhat and not have it run out though the small needle orifice by gravity alone. I gather that the fuel in your engine is a lot lighter and will flow much more readily through tiny holes. Might explain the conflicting advice you're getting somewhat.