Onan Electronic Ignition and TriFuel... How To

[lokay5]

The boss you drilled and tapped is actually the bolt hole boss that's drilled and tapped to hold the original Onan gaseos fuel adapter in place. The larger boss above it is the correct place to tap the carb for venturi vacuum as it is directly in line with the venturi throat on the Marvel-Schebler carb you're working with....

[bobbyz72]

Yes, but i would have to tap a really big hole to get outside of the thin plug, then i would be risking damaging to bowl. I have found that the 1/8 quickly increased to 5/8 hose, is more then enough.

[Jim Rankin]

you might want to simply drill the larger boss above that one and insert a tube with a gasket maker/sealer on it instead of tapping for threads. With a tab welded on it and one screw in the lower boss, it should do fine.

[lijobi]

Man, this is good stuff. Thanks for taking the time to take the pics and show us. I would also like to see some close ups of the stock set up. Having options based on your tool availability and mechanical skills is always a good thing. I have an extra VD 60 carb sitting around waiting for a project like this.

[bobbyz72]

So I ended up finishing it last night. I mixed some epoxy and applied it around my pipe on my taped hole, just to help hold it, but it really is not needed! From the 1/8" i increased quickly to 5/8, to connect my flex hose. You need ATLEAST 1/2 FLEX HOSE!! 3/8 will not do it!

[bobbyz72]

You can see on my demand regulator, i have a T where the natural gas goes into it. Well, thats also a 3/8 flare, where i can turn the gas off at the wall, and connect to a propane bottle, should i ever want to. Just so you all know, dont expect full power when running on natural gas or propane. With Gasoline i can get for then 5 kw out of the generator. On natural gas, expect only about half or a little more then half, and a little more with propane. This has been my experiance with all my generator, and diffrent types of converstions. By the way, Upgrading to electronic Ignition is GREAT!! Test your spark plugs with your points, do the convertion and test them again... much more spark!! You do NOT need to change your ignition coil to a electrionic ignition coil, your points coil will run fine.

[VaughnSimon]

dont expect full power when running on natural gas or propane. With Gasoline i can get for then 5 kw out of the generator. On natural gas, expect only about half or a little more then half, and a little more with propane.

Whoa! The above confuses me.

The older Onans that I am familar with are usually rated the same with any of the three fuels. I assume that they do this by providing a slightly oversize engine to make up for the loss of horsepower when burning the less energetic fuels.

This may not apply to all models, but I can tell you for a fact that if your dry gas CCK conversion is only giving you half power, you are not done yet. Go after the other half!

Thanks for making the effort to document your work for the rest of us. I have been learning a bunch!

Vaughn

[bobbyz72]

Well, then i need other ideas, i have 4. 3 are set up this way, one is a 6.5. And 1 cck with a adaptor. I can not get full power with natural gas. If i open the needle valves up any more, it will start running rich and flooding. Maybe its because i have VERY long exhaust pipes on mine.

[lijobi]

The dry fuel adapter I fabricated for my 5.0 CCK only yeilded me around 4kw with NG and 4.5kw with propane (as I recall). A 4.0 CCK is the same engine as the 5.0, so the full rating will still be realized. My set up was not optimum as it clamped on top of the carb, so one could achieve better results dedicating their machine to one particular fuel and dialing it in for that fuel. My 6.5 NH, which I installed a propane only carb on, will just barely crack out 50 amps at a still reasonable voltage (112), which turns into 5.6kw with NG. it does much better on propane, around 6.2kw or so. If you're only getting about half output on NG, it could be due to the design of the adapter that you threaded into the body. Maybe it needs to somehow stick into the venturi which could help with the vacuum signal reguired by the demand regulator. I lost patience and stopped fiddling with my CCK after the proof of concept was realized. I also played with different size and lengths of tubing between the regulator and the carb, all with different results. If someone is getting full rated output on all three fuels on a machine where the engine is a close match for the genend (i.e. a 10hp motor on a 5KW machine or a 13hp motor on a 6.5kw machine) maybe they could share their set up with us. The reduced output discussion has been brought up on a number of threads and I am always interested to read them.

[hoppyhunts]

Hi Bobby. Thanks for sharing this project with all of us. It's very much appreciated.

I'm just getting my feet wet with generators, and hope to make some type of hobby with them in the future. I have been a forklift mechanic for the past 22 years, and have quite a bit of LP experience, though not much opportunity for LP experiments! Some of the lines of equipment I have worked on have dual-fuel systems and I can back you up in your claim of H.P. loss, but it shouldn't be half. I suspect the fitting you installed into the carb is too small, restricting the fuel. Your 5/8 I.D. hose is then choked down to 1/4 inch I.D., at the 1/8th pipe. Most any system I have worked on (Impco, Aisan, etc.) as well as the dual-fuel air inlet adapter type, maintain the hose size from the regulator to the carb or air inlet hose, but have a fitting with an adjustable restricter to adjust the power. Suppose that may be where the power loss is in your set-up?

Fuel for thought.