Do your own tri-fuel conversion without a collar kit.

[badkins100]

After digging through the internet and examining my commercially modified Honda 3000 carb, I decided to tackle my 23 hp Briggs/Stratton.  As I have said before, I am moderately mechanically inclined, but I normally stay clear of carburetors.  I am sure there are others equally challenged, so maybe this will help them see more clearly how this can be done without the collar kits, or sending your carb off,,, if you dare. 

By feeding propane directly into the carb throat at the venturi, it is said to be the most efficient method, over using collars.  Drilling out the jet orifice and feeding through that would work too, but then you are not tri-fuel, only propane/ng.

This is the beginning of my project as I have 1/4" tubing, bender, and carb gaskets ordered. Today I did my drilling and disassembly and cleaning. I rodded out the jets with tiny wire and flushed it all out with carb cleaner, so I have a clean bowl, float, and jet system.  Hopefully, no more gasoline for this baby.

This 2 barrel carb is great for modifying. It had a shallow indention on either side in perfect alignment with the plane of the gasoline jet outlets in the venturi.  Supposedly this will give the greatest vacuum action upon the propane/ng demand regulator and result is quick crisp operation.

I have reduced my photos to below 100kb each, but I still can't get it to accept them.  Not much good without photos I guess.

[badkins100]

I finally figured out my problem with photos.

[badkins100]

To help avoid confusion for anyone studying the photos, the gasoline fuel inlet tube on top is NOT in the same plane with the gasoline jets in the venturi. Gasoline goes through the inlet tube, into the bowl, and then through the jets located in the middle of the venturi. Also I will have to drill out my 1/4" holes a tiny bit more to allow the 1/4" O.D. tubing to slip in.  A dab of epoxy around the tubing at about 1/4 inch from the tip, which will be slightly protruding inside the venturi, will seal it off and anchor it in place. Then a dressing of epoxy on the outside will further support the tube.  I will post some pictures when I get there. 

[Bruce S]

Nice project you have.
One of the things you might be careful of; most of the epoxies I've tried in the past do not hold up when gasoline is around. Make sure the epoxy you use is for use around fuels
Bruce S

[badkins100]

Thanks for the reminder. That has crossed my mind earlier but I forgot to follow up. I need to go find something appropriate before getting all of my parts in.  I have some 2 part epoxy I used for golf club attachment that I use for everything and I doubt it would be appropriate. The biggest part of this job is getting to the carb and getting it off of the machine. No point in having to go through all that again due to a rough running engine due to an air leak.

[badkins100]

OH Darn!  The tri-fuel mod is going to be a failure.  Looks like I will have a propane/NG generator with no gasoline option.  I got to thinking,,"why were there so many tiny aluminum shavings in the bowl?"

I inspected closer today and found that each of my drill holes intersected 2 internal plumbing tunnels. They appear to be vent tunnels which connect to the surface inside the float area inside the bowl, or they could transport gasoline I guess. I never saw that coming.   Since propane power is far more important to me than gasoline,, I will proceed with the project. If I could get design drawings for the carb, I would buy another one and do the project right.  Anyone know how to go about getting design drawings which would show these hidden tunnels?

[madlabs]

A couple of things that I have done in similar situations:

Drill out a fractional size smaller then the tube, then press fit the tube.

Take a 1/8" NPT male to female compression fitting. Tap the NPT into the carb. Now you can poke the tube in to just where you want it and tighten it in place on the compression side.

I'm not a fan of epoxy and fuels. I admit that there is no real chance of a gasoline leak, but still. I also admit I am a volunteer FF for many years and am a bit paranoid. Still, I would find another way.

Jonathan

[badkins100]

Just to be clear to anyone else wanting to try this conversion,,  You can't drill where I did or you lose the gasoline capabilities and I'm still not sure it's gonna work with propane,, but can't see why it won't make a great propane carburetor. But I could have just removed the main jets from the bowl area and drilled the jet orifices out to accept a hose connector and done the same thing.

30+ years in Mobile Fire/Rescue myself madlabs, 2002, I retired as inspector/investigator.  I also won't abide with any type of fuel leak or potential fuel delivery failure. 

I think the only way to make this carb run on gasoline again would be to have an arthroscopic surgeon implant/splice small tubing into the holes I exposed to replace the integrity of the plumbing. Gasoline is history for this carb. But before I install it and just go with propane, I may order a new carb and use the old one to experiment with drilling position and directions. But,, I might save that $100 and just go with all propane.  I'm done with liquid fuels in generator equipment anyway.  Propane is plentiful and will be delivered after hurricanes shut down refineries down here.  I was without gasoline for a couple of weeks after Katrina, and had to bug out to a friends lake house due to lack of fuel for the generators.  Plus, no more carb problems just when you need the generator most. My Honda 3000 is tri-fuel, but I don't plan to ever put gasoline in the tank again.

You are correct about the gasoline leakage potential if I were to ever use gasoline in this carb again. The engine would probably not run at all with the small internal tunnels I destroyed. Their paths do indeed lead from, and into the gasoline in the bowl so they probably are fuel carrying tunnels. I will get some Loctite Epoxy Weld to seal my propane feed tubes in. It is resistant to most fuels and oils and resists continued 300 degree temps.

[madlabs]

Glad to know you take fuels seriously. I bet you have seen some self-induced grief in your 30 years. :-)

I've been wanting to convert to propane but I would like to keep the possibility for gasoline just in case. My gennys are alternator conversions for direct battery charging. I have a smaller, older one that I don't use any more. Ripe for experimenting plus I have a few extra carb bowls and bits.

Might be easier to just have a propane carb and a gas carb. The Honda motors I like to use have pretty decent access though.

Jonathan

Jonathan

[badkins100]

The spacer/collar adapter is super easy to install for tri-fuel, but I read lots of incidents where they had to be removed to make the engines run smoothly on gasoline. They are easy to remove by removing the breather housing and slip them off. 

A trained carb mechanic can probably pinpoint where to drill on most carbs.  As I inspected my blunder, I ran a small wire (stripped from a bread wrapper tie) into the little tunnels I exposed.  The tiniest passage toward the rear of my drilled hole, (closest to the engine intake valves) connected to nearly invisible holes just outside the throttle butterfly.  That must be low speed fuel.  This tiniest passage appeared to have intersected the slightly larger tiny passage, but I can't be sure because I excavated that area with my drill bit. That passage went from the bowl to somewhere on top of the carb body. So to be tri-fuel, we have to miss all of those passages, and still hit the middle of the venturi.  What we need in order to be successful with drilling a carb is detailed design drawings, blueprints, or x-rays showing hidden passages.  Otherwise, every hole we drill may strike gasoline. Yippee!

[Mary B]

Use a thicker tube, where those hole come in cut a groove around the tube. Figure out a different way to apply epoxy so you don't seal it up.

[badkins100]

I thought about all those ideas too.  Problem is, there is an intersection of 2 tubes (3 way junction) suppose to be right in the middle of my drilling. 

If I had an hourglass type crimp around the propane feed tube which is exactly where the 3 ends of the open passages enter my drilled hole, that may work in restoring the passages. I'd need to be able to push the feed tube into the venturi and apply epoxy to that end, then drag it back to the proper depth and seal the outside against leaks.  A very dull tubing cutter might make such a crimp.  It would have to be pretty precise. I do okay with horseshoes and hand grenades preciseness, but that is about as precise as I can get.    But I am going to think on this idea some.  I will dull a tubing cutter roller blade and see if I can make a deep groove or crimp in the tubing. It's suppose to be welded 1/4" stainless, so I'm not sure I can press a groove in it. Maybe with my Dremel somehow.  This may work.

[Bruce S]

In my younger days, both before ARMY trained me right  , I was a certified engine mechanic/ balance & blueprinter .
From the best I can tell from those pics, that hole is the idler bypass; this is to smooth out cold morning starts, if you've oopsed it don't bother trying to repair, make this carb dual-fuel and put your detail into that.
ON a really good note; Honda is very good about using what works!! take a day and head over to the nearest grease-n-go and see if there's anything out there to use. Better yet call them or a few of the area's finest (PAWN shops) see if there's any to be had on the cheaper than new.
Next item; collars: the issue for getting these to allow the gasoline part to idle correctly is to have the engine tuned for the collar (which is as easy as you taking the air breather off and adjusting the idler set screw) there may be an aluminum cap on it, but a dentist's pick can just get under them to pry off. That's pretty much it.
IF you were north of the mason/dixon line I'd say to have a way to keep the propane slightly warm or a way to giggle the tank, but since you're in hurricane area not too many problems with icing . Unless the movie "Day After Tomorrow" happens.
Cheers;
Bruce S
 

[badkins100]

best I can tell from those pics, that hole is the idler bypass; this is to smooth out cold morning starts, if you've oopsed it don't bother trying to repair, make this carb dual-fuel and put your detail into that.
ON a really good note; Honda is very good about using what works!! take a day and head over to the nearest grease-n-go and see if there's anything out there to use. Better yet call them or a few of the area's finest (PAWN shops) see if there's any to be had on the cheaper than new.

Bruce S

Yeah I think oopsed it, but maybe I can rig around it.   It may not work, but like I said, I have 2 nice Honda's ready to go when needed and this PowerMate is just a backup.  And I don't think I will ever put gasoline in my generators again anyway,, but if I could pull success out of a tri-fuel failure,, that would be fun.

I decided to do a rough polish job inside my bored holes so I could see if there was an intersecting tiny hole on the opposite side barrel.  I made an eye opening discovery of sorts. There is no 90 degree intersection within my bored holes. As I gently polished with my dremel, I noticed the tiniest hole was getting bigger.  The I realized (by looking at the carb body too) I bored right between two vertical  passages. I cut through 2 passages on one side, and only 1 passage on the other side.  I can rod both of these tubes with the bowl off, right into and through my bore holes. Here are some photos to help show how it runs.  I think I can patch the tiniest hole with the fuel proof epoxy and let it sit and harden before inserting the propane feed tube so it will have a barrier against the new epoxy and prevent clogging. Then IF I can cut or press in a reduced waistband at the right position on the propane feed tube, it may let the fully cut passage be connected back. If it works it works, but I will be satisfied with a fine propane powered 10K.  Oh, here are the photos. I tried to draw the passages and show the intrusions I made.

[badkins100]

Would using copper tubing as my propane feed tubes be okay?  I'm not sure whether it will react with the aluminum and do bad things.  The stainless steel tubing I have coming is .028 in thick wall. I think 1/4" copper would give me more wall to grind or crimp my groove into. 

I'm trying to picture myself grinding a somewhat useful groove in a piece of pipe who's walls are as thick as a fat gnat, but without grinding through it.  Bruce is right when he said, "don't bother trying to repair".  It may can be done, and would work fine, but it's probably going to be a big waste of time.  Oh well,, I'm retired. It'll keep me off the streets.

[dnix71]

I have piped in NG from the city for cooking, space heating and hot water. I was told that copper lines were not to be used because the mercaptans added to give the gas a smell would react with copper and residue would eventually flake off and clogs the jets on the appliances. Propane and copper are okay as far as I know.

[badkins100]

I was wondering about sticking a copper tube into aluminum housing.

[Bruce S]

IF the bowl is in fact true Aluminum then you might have an issue with using unprotected copper.
However most carbs I've ever worked on are actually a mixture of metals, we always called it pot-metal. The tubing sticking out of the carb on my 1/2hp motor is copper and the body is pot-metal.
I do not see any issues.
I'm pretty certain that carb is pot-metal as well so you should be okay.
BUT... if that bowl is pure Al then it will corrode instead of the copper, as the copper is a more noble metal than Aluminum.

[badkins100]

Thanks.  It "appears" that both body and bowl are the same thing.  If I need to use copper rather than stainless, I will go for it.  I think I have 2 potential drilling spots for next time, if I do a next time. I may get a wild hair down the road and buy a new carb and try another drilling.  These two spots will work if there is not some hidden passages there and it doesn't appear there are.

[Simen]

I'm guessing your carb are made of aluminium. If it had been made of Zinc Chromate (used from the '30's to late '50's), it would been an olive-green color. That said; Zinc Chromate are still used today in some carburettors. It is my understanding that Zinc shrink very little during the casting/cooling process, so many of the channels etc. can be cast instead of machined afterwards...

[just-doug]

first,what your attemping,is called a "spud in conversion".to pull fuel properly,it must be in the center of the venturi.off-set  and short of center will porform poorly.this when done right,is a main.it will not do idel and intermeddit.without the idell it will be very difficult to start.since it is probable junk for gasoline now,you should comment to propane only.you would do well to talk to a propane pro.great advise and professeion parts are very helpfull.alternative fuel systems inc. located main office in arlington heights,illinois,is where i get all my propane parts and advice.phone 847-437-2345.i think you should call alternative fuel systems for a kit.

[badkins100]

I think MaryAlana had a good idea. If it don't work. No biggie. My intent was to end the gasoline torture.  If I can make it work, cool. I already have some ideas on how to firmly hold the Drexel tool and precisely space the grinding depth. Waiting on tubing.

Use a thicker tube, where those hole come in cut a groove around the tube. Figure out a different way to apply epoxy so you don't seal it up.

[badkins100]

If the intrusions I did were the idle overflow, I may still work fine for gasoline if I plug the intrusions with epoxy, because this gen does not idle. It is either off or on at 3800rpm.

[badkins100]

Or 3600rpm, whatever.

If you've missed it in the heading of the pages here, check out this interesting read on how things unfolded in the mountains of Colorado.  Great reading and pics, and I ordered 5 of her books after reading how profits are needed.
sallyroth.com

[bart]

   Thanks for the link. Picked up a book also.

[badkins100]

It finally hit me that I have a Dremel tool and lots of bits.  Why not tunnel around where the propane feed tubing will be, and pipe the broken passage I drilled through around the tubing.  Here is my progress. I started with a tiny keen edged bit to draw a line between the top and bottom hole of the passage I destroyed.  Then I moved up to a small round ball type bit. After a while being careful to stay straight, the ball follows it's own path in the trench. Then a larger one, finally my biggest, which is much larger than the passage holes I am connecting. I let it eat until it's shaft bottomed out on the outside rim of my bored hole until the grinding ball wouldn't touch anymore metal.  Now, if I take care with the epoxy and not clog the ditches I dug,, the carb should still function as a tri-fuel.  Tubing comes today.

[badkins100]

I bent, cut, and epoxyed the first tube in. I put epoxy in the bore from the venturi side with a toothpick, making sure not to blob it in my freshly dug ditch.  Then I put epoxy on the tube from the depth of the ditch to the outside of the carb body (easy to do by inserting the ball shaped bit, seated it into the ditch and marked it) and slipped it in. Positioned it perfectly. Came back in about 30 minutes and puffed through the bowl end of the once destroyed passage, and it was clear and free flowing.  I will epoxy the other in once this one locks down tight. Once each has cured, I will sculpt the hold on the tubing more robustly.  I only have a few hours at a time to mess with it,, but I think that may be a good thing. I think this ditching around the tubing was a good idea,, but we won't know for sure for a couple more days.  I'm thinking it's a slam-dunk.  I even adjusted the valves on the engine yesterday so I wouldn't have to do that if this engine ran like my little Honda in another thread.

[badkins100]

Success!  I finished buttoning it up this morning (yes I had to take the cowling off 3 times to get it right), hooked it up to the propane feed, primed it with the little spring stem, hit the key and it fired right up, though sluggish, until I grabbed the little load valve and found that wide open was perfect. I put 3000 watts on it and could scarcely hear any change, of course it is a 10000 watt machine.  I was planning to remove the load valve and just use an elbow since it works best wide open,, but it probably would be needed when switching over to gasoline, but I don't know for sure.

It actually ran better than before I violated it.  The valves and plugs adjustment is probably the reason for that.  I let it run for 15 minutes or so and it was as smooth as silk. Then shut the propane off and added a little gasoline to the tank to see if she still liked liquid fuel.  I choked it and hit the key and it fired right up, ran perfectly.  I reached in and pulled the throttle back to idle just to see if my idle overflow repair was a success, and it would idle at any speed, including down to a Harley type idle.   I shut off the gasoline and started trying to rid the carb of it by choking etc. I did a good choking  under propane power too. I did leave the gasoline fuel line open to the carb through the little inline filter where I removed the fuel tank line, and the engine don't seem to notice it.

Hopefully all of this will help someone else who is thinking about doing the tri-fuel themselves. It was slightly over my head and I nearly ended up with bi-fuel, due to not realizing I was drilling through a cast or machined fuel passage in the wall of the carb.  The work-around may help others too.  Just remember that positioning your propane feed tube in the venturi itself is important. And the angle cut on the tube can't hurt at all. The collar of the tube should act as a collar against the wind at the back on a coat.  But the tube collar also creates a low pressure area right at the propane fuel flow and no rushing air is directed into the feed tube. My Honda 3000 had no collar when I got it back from the mod-builder and it seems to run fine, but still, if you are doing it, a little time to fit such things is not a biggie. Also put a little more thought into the tubing bending than I did. I thought that running them out just under the breather pan would be best. I should have gone out the back so I could have made a neater fit of hoses.  Both 1/4" hoses to my feed pipes are cut the same length, just to prevent any possible loss or gain in the vacuum and supply amounts.  Take your time. It's easy if you go slow. But putting the cowling on it the real p-i-t-a.

[Bruce S]

Great NEWS!!!
When you get the chance. Can you make a list of the items used for adding the propane?
This will help others news to DIY.
Cheers
Time for a cold one!!!

[badkins100]

Sure.  I will list the things and add comments about them below. Sounds like a lot, but it is all part of 2 main assemblies. Carb and regulator.  I did shorten my feed hoses to the carb feed tubes and made that a much neater job.


For the regulator:
1 - Garretson IMCO Style KN Low Pressure Regulator. It is a demand and NOT intended to take propane pressure right from a tank. 
1 - 3/4" to 3/8" NPT thread I think (or 1/2" if running a longer hose).
1 - 3/8" (or 1/2") barbed hose connection for the regulator propane feed hose.
1 - 3/8" NPT load block. (screws into the top of the regulator to fine tune vacuum and propane flow)*
1 - 3/8"NPT  thread to 3/8" hose barbed nipple for propane supply to carb modified propane feed tube.

For the Carburetor
1 - Set of gaskets for any parts of the carb you may have to separate, and I advise to at lease remove the bowl for cleaning and to make sure no tiny passages are running through where you want to drill.
2' - 1/4" O.D. steel, copper, or stainless steel tubing.  I used around 1 foot.
1 - Tubing bender for small tubing.
1 - 1/4" drill bit and drill motor.
1 - Pack of JB Weld epoxy (fuel and chem resistant)
? - 1/4" I.D. fuel hose to run from new feed tube to the 3/8" I.D. hose from the regulator.
1 - 1/4" to 3/8" double male barbed fitting to join the 1/4" and 3/8" hose.
? - 3/8" I.D. fuel hose to run from regulator to 1/4" I.D. supply to carb tubes.
1 - Supply hose to connect to the bottom fitting on the regulator and to your propane supply.


I got my regulator from ebay for 70 bucks with free shipping)

Looking at the picture of the regulator, you can see that you need to reduce the 3/4 inlet for the regulator down to whatever you use to connect to your regulated propane supply.(11" water column pressure)

*I could not find the standard loading block online or around here so I used the small ball valve, which doesn't seem to be needed on this setup.  I'm thinking they are made from 3/8"NPT T with a male thread nipple going into the regulator, a straight stud screwed into one of the other holes to block the flow somewhat, and the barbed nipple for the feed hose to the carb. They are called a Load Block, but I never found anything like they provide with kits.

Since I had twin cylinders and 2 barrels on the carb, I used 2 feed tubes, one into each venturi.

I ordered 3 feet of 1/4" stainless steel seamless tubing from Amazon and used about a foot. Probably could get by with 10 inches now that I have done it once.  I also bought a Klein tubing bender because you need as close a 90 degree bend as you can get in some instances. Also a Dremel type tool with bits is invaluable.  It allowed me to save my tri-fuel project from being just a bi-fuel.

The JB Weld worked great.  Mix the two parts with a tootpick and paint it on the preformed and shaped feed tubes. Slide them in and position them properly and let them cure for a couple of hours. Then mix some more and make your bond from tube to carb body more robust. Careful, it will try to run for the first hour, so you may have to babysit it to keep it from running or dripping where it is not suppose to be.  I got some in the bolt channel on both sides and once cured, I couldn't cut it out with a knife. I had to use the Dremel and a round grinding bit.  Be sure to wipe the venturi area clear of blobs of epoxy and be careful not to clog the tiny holes in the venturi near the throttle butterfly.

I'm happy to share all this because this site helped me figure out my Honda EU3000 problem. I think you can learn and fix anything by studying it on the internet, and it is frustrating to never quite hit on what your specific problem is.

If you think you might want to do a tri-fuel modification,, remove the breather and it's shrouds so you can get a good look at your carb.  If you have room, and if you can see the venturi area from the outside without any obstructions, you can proceed with removing the carb. Make good closeup photos of linkage, hoses, and brackets so you can refer to them during assembly. Then come here and we will help guide you if you can post photos.    It's actually easier than you think. I just added to my project by not inspecting my carb close enough.  I gotta go eat. Hope I didn't forget anything.

[badkins100]

I failed to call the fitting a "reducer" and the time to modify the post ran out.

For the regulator:
1 - Garretson IMCO Style KN Low Pressure Regulator. It is a demand and NOT intended to take propane pressure right from a tank. 
1 - 3/4" to 3/8" NPT thread reducer, (or 3/4" to 1/2" if running a longer hose).
1 - 3/8" (or 1/2") barbed hose connection for the regulator propane feed hose.
1 - 3/8" NPT load block. (screws into the top of the regulator to fine tune vacuum and propane flow)*
1 - 3/8"NPT  thread to 3/8" hose barbed nipple for propane supply to carb modified propane feed tube.

[badkins100]

I finally found the parts to build the nice compact Load Block for the regulator.  No wonder I couldn't find them to buy. Kit builders must be making them for their kits.  Ancient Chinese Secret.   The nut is a jamb nut to lock the threaded stud once final adjustments are done for a smooth running engine with reserve to quickly handle the demand load.

[badkins100]

A couple of shots of a retired firefighters engine room.  Something in our dna seems to make us think that if it came from the factory shiny, we should keep it shiny.

First is the 16kw, propane only.
Second is the super quiet Honda 3kw and the super loud Coleman 10kw. Both recently converted to gasoline, propane, or natural gas.  Our lights will certainly never go out again.