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LP to NG: What is required?


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Old 10-10-2017, 11:39:00 AM
JT240Z JT240Z is offline
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Default LP to NG: What is required?

I currently have a JC genset that has the "tri-fuel" option. I know it will run on gasoline and it was originally set up for either LP or NG. Not sure yet. Exactly what would be required to change from LP to NG or from NG to LP? If it matters, it already has a demand regulator that feeds the carb through a relatively large diameter hose.

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Old 10-10-2017, 12:12:56 PM
Mac Sine Mac Sine is offline
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Default Re: LP to NG: What is required?

For LP (propane) fuel you will need a primary regulator upstream of the demand regulator, feeding a positive pressure not to exceed the maximum inlet pressure value that us stamped on the body of the demand regulator.

For natural gas fuel you may or may not need a primary regulator upstream of the demand regulator, depending on the pressure of the natural gas supply.

A slight adjustment of the carburetor main jet load screw will be needed to trim between propane and natural gas, because of the difference in the heat content between the two fuels.

Optimum spark timing is also different between propane and natural gas. The unit-specific instruction book will provide these values.
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Old 10-10-2017, 01:01:54 PM
JT240Z JT240Z is offline
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Default Re: LP to NG: What is required?

I've checked the operators manual (967-0120) and found nothing about carburetor adjustments between fuel sources. The references that I have seen are to making sure that both gaseous and liquid fuels not being turned on at the same time.
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Old 10-10-2017, 06:54:13 PM
Max Thompson Max Thompson is offline
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Default Re: LP to NG: What is required?

Timing and spark plug gap is the same for both gaseous fuels. It should start on either one with no adjustments. As mentioned above, you may have to make some minor carb adjustments after you get it running, you will need a way to load the generator and measure the frequency (Hz.) and voltage in order to get all carb and governor adjustments correct.

Many of us use a "Kill-a-watt" meter to measure frequency. They are around $20 at the box store or on-line.
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Old 10-10-2017, 07:56:46 PM
JT240Z JT240Z is offline
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Default Re: LP to NG: What is required?

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Originally Posted by Max Thompson View Post
Timing and spark plug gap is the same for both gaseous fuels. It should start on either one with no adjustments. As mentioned above, you may have to make some minor carb adjustments after you get it running, you will need a way to load the generator and measure the frequency (Hz.) and voltage in order to get all carb and governor adjustments correct.

Many of us use a "Kill-a-watt" meter to measure frequency. They are around $20 at the box store or on-line.
Plan on doing a complete load test and adjust once I get her fired up.

Already have one of these and a Fluke 177 meter to do the job:



http://www.homedepot.com/p/Klein-Too...L310/207144577
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Old 10-18-2017, 12:46:17 PM
JT240Z JT240Z is offline
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Default Re: LP to NG: What is required?

I keep hearing of the "slight adjustment" that's needed at the carburetor to go between LP and NG. Can someone give me an idea of how that adjustment would be made or point me in the right direction on any documents that would explain it? Looking for something a little more detailed than "turn the screw".
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Old 10-18-2017, 04:50:35 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: LP to NG: What is required?

That is all there is to it. Turn the large mixture screw until it runs smooth. There is a adjustment rig you can buy. Set you back about 500.00 dollars.
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Old 10-18-2017, 06:18:49 PM
Birken Vogt Birken Vogt is offline
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Default Re: LP to NG: What is required?

Also check and recheck for reliable starting, it is a balance between regulator setting and fuel mixture adjustment at full load to get it to start reliably and run good at full load.

Usually very easy, lots of wiggle room.
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Old 10-18-2017, 08:44:10 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: LP to NG: What is required?

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Originally Posted by JT240Z View Post
... Looking for something a little more detailed than "turn the screw"....
What I do is load the set to near 100% and monitor the frequency. Then adjust the main mixture screw for max frequency or ever-so-slightly richer than max. If you can't fully load the set, you can't properly set the mixture, as far as I'm concerned. You can get close, but the final setting ought to be under full load.

After that, remove the load and fiddle with the 'idle' screw until you get pissed off that it doesn't do much. Then repeat the above step.

From what I've read and understood, one does NOT adjust the regulator this way. The regulator is basically adjusted to be as close to 0 psi as possible without leaking gas. If you have a new-ish Garretson KN, just don't dick with it. It's probably fine and you can easily do more harm than good.

Last edited by Jim McIntyre; 10-18-2017 at 10:17:18 PM.
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Old 10-18-2017, 10:40:49 PM
JohnnyC JohnnyC is offline
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Default Re: LP to NG: What is required?

Quote:
Originally Posted by JT240Z View Post
I keep hearing of the "slight adjustment" that's needed at the carburetor to go between LP and NG. Can someone give me an idea of how that adjustment would be made or point me in the right direction on any documents that would explain it? Looking for something a little more detailed than "turn the screw".
To specifically answer your question, please refer to the arrow in the picture below ( a picture is worth a thousand words).

If the carburetor was already set for PROPANE, you may need to rotate the screw counter clockwise to allow more vapor. Fine tune as needed. 1/4 turn can have dramatic results / changes in the engine's performance.

JohnnyC
New Jersey
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Old 10-18-2017, 10:50:49 PM
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Default Re: LP to NG: What is required?

Quote:
Originally Posted by JT240Z View Post
I've checked the operators manual (967-0120) and found nothing about carburetor adjustments between fuel sources. The references that I have seen are to making sure that both gaseous and liquid fuels not being turned on at the same time.
Look in the engine manual (967-0754), 1-1996, page 26.
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