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empire pilot
Posted by: Eric Gleason (IP Logged)
Date: December 19, 2002 12:24AM
<HTML>Hi,
Still having some trouble getting my empire pilot to burn well. I started out using unleaded in it but kept getting a lot of yellow flame. Tried different fuel pressures and added a needle valve to help fine tune the flow but nothing really seemed to help. So, I tried kerosene and had much the same results. I now rigged it up to burn outside the car on a bed of fire bricks, making sure to keep the intake clear, and still have the same trouble, basicly when it is burning strong it has about a 12" tall flame, mostly yellow with about the lower 1/4" being blue. Wide open it burns about 1/4" above the pilot casting with 10 lbs of pressure in the tank. If I turn it down some the flame gets weak and wispy and stops burning at the far end of the pilot. Right now the oriface or jet size is about that of a #57 drill bit. Could that be the problem, too much fuel coming out? I can not seem to locate any caps the same size as the oriface nozzle so I could not try drilling them out to try different sizes. I tried inserting copper plug washers with smaller punched holes into the jet but I think I still got some leakage around them so I might not have limited the flow much. Anyone have any suggestions?</HTML>
Still having some trouble getting my empire pilot to burn well. I started out using unleaded in it but kept getting a lot of yellow flame. Tried different fuel pressures and added a needle valve to help fine tune the flow but nothing really seemed to help. So, I tried kerosene and had much the same results. I now rigged it up to burn outside the car on a bed of fire bricks, making sure to keep the intake clear, and still have the same trouble, basicly when it is burning strong it has about a 12" tall flame, mostly yellow with about the lower 1/4" being blue. Wide open it burns about 1/4" above the pilot casting with 10 lbs of pressure in the tank. If I turn it down some the flame gets weak and wispy and stops burning at the far end of the pilot. Right now the oriface or jet size is about that of a #57 drill bit. Could that be the problem, too much fuel coming out? I can not seem to locate any caps the same size as the oriface nozzle so I could not try drilling them out to try different sizes. I tried inserting copper plug washers with smaller punched holes into the jet but I think I still got some leakage around them so I might not have limited the flow much. Anyone have any suggestions?</HTML>
Re: empire pilot
Posted by: Mike Clark (IP Logged)
Date: December 19, 2002 10:25AM
<HTML>Eric
Your pilot problem may stem from the fact that you are using fuel with too high a boiling point. I know the Cruban is supposed to work on unleaded but present day unleaded is very diffent to the old stuff.
The type of pilot where the fuel is vaporised in a looped tube and then comes back out to the front allows fuels like unleaded to cool down and condense again before getting back into the jet. The problem would be even worse with kerosene. Check the temperature of the nozzle.
I investigated fuel temperature when I had the problem you describe and sure enough even with the vaporiser tube red hot at 1100 F the fuel drops to 400 F as soon as it gets outside the burner casing and is down to 190 F at the jet. Even at 320 F only 85% of unleaded would be vaporised. When the fuel condenses at the jet it has a much smaller volume than the fully vaporised gas, so squirts through much faster and makes a flaring, smoky flame. The semi liquid fuel draws less air weight for weight of fuel than the gas because a droplet of fuel can’t kick as many air molecules as it would if it were itself split up into molecules. (This cooling effect is not a problem with the main burner and exposed front branch forks and jets simply because the rate of flow of hot fuel is so much faster, the fuel emerging from the jets at 750 F.
Many people in the UK use industrial hexane as pilot fuel. This, being a single paraffin hydrocarbon, has a boiling point of 156 F so is still a gas when it gets to the jet. Unleaded, in contrast, because it has so many constituent hydrocarbons, boils over a range from 95 F to as much as 425 F, so a big part of it is back to liquid at the jet. The snag with hexane is that we can only buy it in cans which are too big to be legally kept at home and no one will ship it.
Coleman fuel is commonly used in the US but I suspect is not as good as hexane since it seems to contain a wider range of hydrocarbons.
The Maxwell type of pilot (which has its own problems – don’t they all) doesn’t suffer from cool fuel as the jet is right inside the burner. It just does not give a strong enough flame.
Mike</HTML>
Your pilot problem may stem from the fact that you are using fuel with too high a boiling point. I know the Cruban is supposed to work on unleaded but present day unleaded is very diffent to the old stuff.
The type of pilot where the fuel is vaporised in a looped tube and then comes back out to the front allows fuels like unleaded to cool down and condense again before getting back into the jet. The problem would be even worse with kerosene. Check the temperature of the nozzle.
I investigated fuel temperature when I had the problem you describe and sure enough even with the vaporiser tube red hot at 1100 F the fuel drops to 400 F as soon as it gets outside the burner casing and is down to 190 F at the jet. Even at 320 F only 85% of unleaded would be vaporised. When the fuel condenses at the jet it has a much smaller volume than the fully vaporised gas, so squirts through much faster and makes a flaring, smoky flame. The semi liquid fuel draws less air weight for weight of fuel than the gas because a droplet of fuel can’t kick as many air molecules as it would if it were itself split up into molecules. (This cooling effect is not a problem with the main burner and exposed front branch forks and jets simply because the rate of flow of hot fuel is so much faster, the fuel emerging from the jets at 750 F.
Many people in the UK use industrial hexane as pilot fuel. This, being a single paraffin hydrocarbon, has a boiling point of 156 F so is still a gas when it gets to the jet. Unleaded, in contrast, because it has so many constituent hydrocarbons, boils over a range from 95 F to as much as 425 F, so a big part of it is back to liquid at the jet. The snag with hexane is that we can only buy it in cans which are too big to be legally kept at home and no one will ship it.
Coleman fuel is commonly used in the US but I suspect is not as good as hexane since it seems to contain a wider range of hydrocarbons.
The Maxwell type of pilot (which has its own problems – don’t they all) doesn’t suffer from cool fuel as the jet is right inside the burner. It just does not give a strong enough flame.
Mike</HTML>
Re: empire pilot
Posted by: Pat Farrell (IP Logged)
Date: December 19, 2002 02:07PM
<HTML>Dear Eric, With a 12 inch high yellow pilot flame, you are much too rich. Too much fuel. To lean it out, several factors as have been already suggested need to be applied. In a search for a smaller jet size, in the past, I have peaned the jet smaller with a punch. If you go too small, usually a small torch tip cleaner can ream it larger. If needed, a lower fuel pressure of 5 to 10 pounds will usually give you better vaporization than the 30 pounds that is sometimes seen. For over 22,000 miles, I have always used the Maxwell pilot and with Coleman fuel, I haven't had any problems with carbon build up. I clean out my pilot vaporizer about every 5,000 miles. The flame that you want to see is a blue flame with a hint of yellow at it's tips. The flame should be not more than an inch high. The flame should just be off the burner and not be touching it. If the flame is touching the burner, in time the heat conducted to the burner will eventually burn out the pilot burner. The environment for the pilot changes continually while the car is in motion. For this reason, I run a little higher flame while I am traveling, and when I park the car for lunch, I will turn the pilot flame down a bit for flame stability.</HTML>
Re: empire pilot
Posted by: David K Nergaard (IP Logged)
Date: December 19, 2002 02:30PM
<HTML>I would definately consider a smaller jet. I think #57 drill size is too big for the main burner, let alone a pilot! The usual Stanley pilot jet ia a #64 drill size, with a wire with a flat on one side nearly filling the jet hole. The flat is typically 0.007 inches deep. The equivalent hole size is probably not much larger than #80 drill.</HTML>
Re: empire pilot
Posted by: Mike Clark (IP Logged)
Date: December 19, 2002 05:47PM
<HTML>Eric
I knew I’d seen it somewhere. In Light Steam Power magazine October 1951 there is a picture and comments on experience of the Cruban Pilot. I can see from the picture that the pilot vaporiser runs around almost outside the flame not in it which is good as it won’t cook the fuel and get coked up. The jet is actually rather well connected to the body of the pilot by metalwork, much more than in the Stanley pilot, probably helping to maintain heat in the fuel and not so likely to get fuel condensing as I suggested earlier.
The article says that the nozzle is the same size as the main burner nozzle but (like the Stanley pilot) has a wire through it with a flat filed to control the flow. The author said it was a good pilot on unleaded but did need to have the wire tweaked often to keep the nozzle clean. The pressure used was 30psi. The pilot air intake is a tube about 4 inches long connecting to a casing around the jet and drawing air from below the main burner air intakes. I presume your pilot is one of these.
My suggestion is that you try a bit of extra heat on the outside of the jet area with your gas torch. This will show if the fuel is condensing at the jet. If this doesn’t fix it try a careful squirt of air from an airline up the air intake. This will show whether you have too little air which is the next most likely cause of a yellow flame. If extra air does help then (as you have no adjustment for air) you need to fiddle with the effective jet size and pilot fuel pressure. The problem is all these things interact – if you push too much fuel in it doesn’t get vaporised and doesn’t pull enough air. Less fuel and more pressure may be better.
PS I absolutely agree with David's comments on jet size - the Maxwell jet is even smaller than no.80.
Mike</HTML>
I knew I’d seen it somewhere. In Light Steam Power magazine October 1951 there is a picture and comments on experience of the Cruban Pilot. I can see from the picture that the pilot vaporiser runs around almost outside the flame not in it which is good as it won’t cook the fuel and get coked up. The jet is actually rather well connected to the body of the pilot by metalwork, much more than in the Stanley pilot, probably helping to maintain heat in the fuel and not so likely to get fuel condensing as I suggested earlier.
The article says that the nozzle is the same size as the main burner nozzle but (like the Stanley pilot) has a wire through it with a flat filed to control the flow. The author said it was a good pilot on unleaded but did need to have the wire tweaked often to keep the nozzle clean. The pressure used was 30psi. The pilot air intake is a tube about 4 inches long connecting to a casing around the jet and drawing air from below the main burner air intakes. I presume your pilot is one of these.
My suggestion is that you try a bit of extra heat on the outside of the jet area with your gas torch. This will show if the fuel is condensing at the jet. If this doesn’t fix it try a careful squirt of air from an airline up the air intake. This will show whether you have too little air which is the next most likely cause of a yellow flame. If extra air does help then (as you have no adjustment for air) you need to fiddle with the effective jet size and pilot fuel pressure. The problem is all these things interact – if you push too much fuel in it doesn’t get vaporised and doesn’t pull enough air. Less fuel and more pressure may be better.
PS I absolutely agree with David's comments on jet size - the Maxwell jet is even smaller than no.80.
Mike</HTML>
Re: empire pilot
Posted by: Jeff Theobald (IP Logged)
Date: December 19, 2002 08:10PM
<HTML>Hi Eric,
The Brooks runs this type of pilot, (Cruban) I have run it for many years on unleaded petrol without any problems, I run the fuel pressure at 25 to 30 psi and set it up on the bench, I use darning needles silver soldered to the back screw at a point where it seals the jet when assembled, and then file a flat until by trial and error I get a good strong burn as Pat discribed, for many years I used to bury the pilot in fire cement until it was halfway up the vaporiser, this kept it very stable and protected from the main fire, it would run all day without any attention, the problem is this makes it difficult to get out to clean, so I am now leaving it exposed, up to now it's been OK, from what you discribe with your pilot I would also say far to much fuel, ether decrease your jet size, fit a new needle, and increase your fuel pressure to 25 psi, reducing the jet size will slow the fuel flow and increase the temp at the jet, the higher pressure will draw more air, hope this helps, Jeff.</HTML>
The Brooks runs this type of pilot, (Cruban) I have run it for many years on unleaded petrol without any problems, I run the fuel pressure at 25 to 30 psi and set it up on the bench, I use darning needles silver soldered to the back screw at a point where it seals the jet when assembled, and then file a flat until by trial and error I get a good strong burn as Pat discribed, for many years I used to bury the pilot in fire cement until it was halfway up the vaporiser, this kept it very stable and protected from the main fire, it would run all day without any attention, the problem is this makes it difficult to get out to clean, so I am now leaving it exposed, up to now it's been OK, from what you discribe with your pilot I would also say far to much fuel, ether decrease your jet size, fit a new needle, and increase your fuel pressure to 25 psi, reducing the jet size will slow the fuel flow and increase the temp at the jet, the higher pressure will draw more air, hope this helps, Jeff.</HTML>
Re: empire pilot
Posted by: Pat Farrell (IP Logged)
Date: December 19, 2002 09:22PM
<HTML>The smaller jet size with a cleaning wire with-in should to be the fix for the pilot. With a smaller jet, a higher fuel pressure can then be used for a leaner flame. My lower pressure suggestion was for fuel vaporization. Fuel will vaporize at a lower pressure sooner than it will at a higher pressure for the same temperature. Like water boiling at a mountain top at a lower temperature than 212 degrees. The lower pressure makes a pretty wimpy pilot flame though.</HTML>
Re: empire pilot
Posted by: Eric Gleason (IP Logged)
Date: December 22, 2002 01:49AM
<HTML>Well, thanks everyone! It worked! The trick was to extend my needle out to the point that it just extended beyond the end of the jet when assembled. The needle in this car is carried in a small sleeve that treads into the cleaning screw. When I got the car the needle length was such that it did not extend into the orifice and , after cleaning and everything I just put it back the way it was. Well, I took out the needle, pushed the extra length out of the sleeve and lit things up and it burned really well! I also switched to Coleman Fuel as well. Might try to fire-up after X-mas!</HTML>
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