Natural gas conversion - where to feed the gas

   #1  

Travelover

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I'm converting a small gas generator to allow for it to be able to run on gasoline or natural gas. Most of the commercially available kits add a small venturi between the between the carb and the air cleaner. This causes packaging problems and messes with the choke linkage, so I'd like to apply the gas either to a tapped inlet on the manifold or directly in front of the inlet in the air cleaner box. The inlet pipe has to have a small vacuum in order to open the regulator valve, which functions as a safety device so the gas quits flowing if the engine stops.

Anyone done this or have experience with propane / natural gas engine intake systems?


Generator Conversion Kits to Propane and Natural Gas.
 
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   #2  

RNeumann

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Good luck- I’ll give this a bump for you just cuz I’m curious.

If I’m reading it right it looks like you are trying to add propane (like a diesel with propane injection) rather than eliminate gasoline. The only tri fuel gen I’ve seen was an old Onan. But that required some carb parts change etc to switch from one fuel to another. I’m not sure how a simple valve that opens with vacuum could be the only fuel. Starting and cold running are two areas that would need more attention.
 
  
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Travelover

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Good luck- I’ll give this a bump for you just cuz I’m curious.

If I’m reading it right it looks like you are trying to add propane (like a diesel with propane injection) rather than eliminate gasoline. The only tri fuel gen I’ve seen was an old Onan. But that required some carb parts change etc to switch from one fuel to another. I’m not sure how a simple valve that opens with vacuum could be the only fuel. Starting and cold running are two areas that would need more attention.
I'm adding natural gas, not propane. That is relevant because propane requires a bit more effort to get it properly vaporized and mixed with the incoming air than natural gas. There are several companies that sell these conversion kits and they all have the same basic components - I linked one of them in my initial post. Generators are easier to convert to natural gas or propane, as they run at a constant rpm.
 
   #4  

pmsmechanic

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You still need some kind of a venturi device to meter the natural gas. Yes generators run at a constant speed but they don't run under a constant load.
 
   #5  

Rocky J

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I converted my generac 10 hp Briggs over to Propane . I did not buy a kit , I used a on demand regulator like you are talking about. It was intended for a floor scrubber . I removed the carb to get to the plastic spacer that is between the carb and the block. I drilled and tapped a hole for a barb fitting , this was for the vacuum line that shuts off the full if the engine quits,any place on the engine side of the throttle plate will work, like you said safety devise . I drilled a hole in the back of the plastic air cleaner just a little smaller then the rubber vapor feed hose from the regulator , pulled it over in front of the inlet , cut the hose at a little angle to get it close , this is on the engine side of the air FILTER , this is where you get the vacuum to open the diaphragm in the regulator ,the closer the regulator the better because less hose to build vacuum in,be sure to mount the regulator vertical not horizontal, if laid down flat the weight of the diaphragm will through off the calibration of your regulator , mine starts second pull. I put the same regulator on my Toro Grounds Master and on my Case loader with my only problem is the 20 pound grill tank will freeze up at times but not many because of the larger engines calling for more vapor then the tank will naturally make.
 
  
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Travelover

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I converted my generac 10 hp Briggs over to Propane . I did not buy a kit , I used a on demand regulator like you are talking about. It was intended for a floor scrubber . I removed the carb to get to the plastic spacer that is between the carb and the block. I drilled and tapped a hole for a barb fitting , this was for the vacuum line that shuts off the full if the engine quits,any place on the engine side of the throttle plate will work, like you said safety devise . I drilled a hole in the back of the plastic air cleaner just a little smaller then the rubber vapor feed hose from the regulator , pulled it over in front of the inlet , cut the hose at a little angle to get it close , this is on the engine side of the air FILTER , this is where you get the vacuum to open the diaphragm in the regulator ,the closer the regulator the better because less hose to build vacuum in,be sure to mount the regulator vertical not horizontal, if laid down flat the weight of the diaphragm will through off the calibration of your regulator , mine starts second pull. I put the same regulator on my Toro Grounds Master and on my Case loader with my only problem is the 20 pound grill tank will freeze up at times but not many because of the larger engines calling for more vapor then the tank will naturally make.
Thanks, this is exactly the kind of information I was looking for. The regulator I'm using, a Garretson, is the same one used by the three major retrofit companies. It does not use a separate vacuum line, it is set up so the engine has to pull the gas through. I think this also allows for varying gas feed depending on load.

Regulator Garretson KN Beam Impco how valve works for Propane or Natural gas generator - YouTube
 
   #7  

Rocky J

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Thanks, this is exactly the kind of information I was looking for. The regulator I'm using, a Garretson, is the same one used by the three major retrofit companies. It does not use a separate vacuum line, it is set up so the engine has to pull the gas through. I think this also allows for varying gas feed depending on load.

Regulator Garretson KN Beam Impco how valve works for Propane or Natural gas generator - YouTube

Yes, it sounds and runs like it is on gasoline, throttles up and idles and follows the Governor for rpms . I remember my generator running a little rich, slight black smoke when I first started it after converting it , they make a adjustable inline valve to correct it , goes between the regulator and carb. I pinched my vapor feed line a little and it cleared right up so I cut a one inch long piece of thin hose that fit inside the vapor feed line to restrict it like a orifice. Got lucky first time, runs on propane better then gasoline, well better then 2 year old gasoline that I normally had in the tank when I needed it.
 
   #8  

thatguy

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i converted two EU2000 inverter generators using the US Carb 'snorkel' kit to run on propane.. took longer to figure out where to mount the regulator than do the actual conversion..

Ran both generators for a total of 30 hrs a few months back without any issues.. Much better set up than trying to store 15 gallons of gas

brian
 
   #9  

thatguy

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every now and then US Carb run holiday specials - I got my kits for 50% off normal price..
 
 
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