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Discussion Starter · #1 ·
Hello guys! Still pretty new here, I have lurked around for a while and posted very little thought I would start a thread for my mower. This will cover more than just the propane aspect but other modifications I am doing to the mower. The first few pictures will be of the propane conversion kit I did on it last year.

I removed the stock carburetor and replaced with with a propane mixer with a throttle body that matched the intake (losing my governor... Ill get to that later)

I also removed the gas tank and mounted my regulator. Out the back I attached two pieces of angle to hold my 20lb tank.


All of these pictures are from last year, it did well over the whole season mowing 3.5 acres weekly the whole season.

Due to my governor being eliminated, I had to manually control my throttle which was a pain but got me by last year, in the next month or two I plan to give a walk through on modifying the stock carburetor for propane so I can have my governor back!

Here it sits as of yesterday, tore some of it down to begin prepping for spring!
 

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Discussion Starter · #2 ·
This evening I tore a little bit more apart :) My first step in building this up for spring time was to upgrade my hitch!

Cut up some scrap 3/16" steel...


Welded on a thicker piece from something, it was threaded...


Original...


Prepped...


First part welded...


Second piece cut...


Welded in place...


Bracing cut...


Probably a little overkill, but I didn't want it being as weak as the old one. Welded in place...


Ball in place!


Should hold up better than the old one!


Tomorrow I will work on the tank mounting. If you guys have any questions or suggestions, let me know :)
 

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Subscribed! :)

Very nice, this will be a fantastic project to follow. Thank you for taking us along for the ride.

What made you decide to convert it to a propane setup, might I ask?
 

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Discussion Starter · #4 ·
I started working for a friend of mine who owns a company that does conversion kits on automotive and industrial applications. After I started working with propane for a while, learned more about it, I ended up preferring it over gasoline!

First off, propane does not go bad, you shut your engine down, let it sit 6 months, walk out and start it right back up, no fuel degradation.

Second, it is very easy to work with, a rich/lean idle adjustment and rich/lean full load adjustment, once those are set correctly, fuel and air are drawn to the engine upon demand. There are no jets to clog or float bowls to varnish or fuel pumps to fail (propane is stored under pressure, no pump needed), you can usually get around 10 years of use from the diaphragms in the regulators before a rebuild kit is needed which will run you round $30.

Third, propane is very clean, has very low carbon so the engine stays clean on the inside (although your oil will still breakdown from usage, it will not turn black, still looks the same when you drain it as when you put it in!) it is a superior fuel compared to gasoline when it comes to carbon footprint.

Last off, this will depend on where you are located, propane is generally cheaper than gasoline. During my mowing season, propane maxed out at $1.99 per gallon while gas got up to around $3.45 Depending on where you get your propane from, the quality may vary and you can have a loss in power/economy, fortunately where I was buying from,the propane was on par with gasoline and my usage was almost identical.

The cons of propane...

First is where you are located. Propane prices will vary up and down widely throughout the states, a few of our customers get propane for $0.47 per gallon, and others unfortunately pay $6.00+ for it.

Second, propane averages around 110 octane and will burn hotter than gasoline, if you do not set your rich/lean idle and full load adjustments correctly, you can burn up your exhaust valves.

Third, if you are running your engine in -15° or lower, you will probably need to heat your tank if it is small (20lb tank)
 

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This will be interesting. I've been looking forward to seeing a thread by you on this since you first joined MLF. Thanks for sharing it with us.
 

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This is a cool project for sure!!! :)
 

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Discussion Starter · #10 ·
Thanks for all the feedback guys! I will provide as much information as I can!

:ditto: Me too for sure!

I have run push mowers on small blow torch cylinders before just using aquarium hose and some zip ties.. Never tried running a tractor before, But It seems pretty easily done..

-Stan
There are some companies that offer kits like these, they work ok but dont deliver fuel upon demand so as the load level on the engine changes, the air fuel ratios bounce all around the place.
 

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Discussion Starter · #11 ·
This is a model J regulator/vaporizer


This regulator will work with 1-100hp engines and will work with vapor withdraw (20lb grill tank or larger grill/heater standard tank) and will also work with liquid withdraw (forklift or automotive tanks) as long as they are heated by engine coolant or oil. You can use vapor tanks on everything up to around 40hp depending on your climate. Larger engines require liquid withdraw. These tanks draw from the bottom of the propane tank (the liquid propane) and have controlled vaporization to deliver large amounts of vapor propane upon demand.

OK, back to my regulator! I have an 18hp engine so I am using a 20lb grill tank which is vapor withdraw. I have modified a standard acme fitting by drilling out the internal overflow valve to allow full flow (I dont like taking the tank connection on and off with a wrench!)


This regulator takes full tank pressure (30-312psi) internally brings the pressure down to -1.5" WC and then allows fuel to travel to the mixer (similar to gasoline carburetor) upon demand.

This is the mixer, it replaces the gasoline carburetor, or if you want to do a dual fuel conversion (gasoline OR propane) will mount between the air cleaner and gasoline carburetor.


You can see the vapor inlet, simple throttle plate and the rich/lean idle adjustment (large flat head screw with spring). The power valve (rich/lean full load adjustment) is not visible but is on top of the fuel inlet. Also you see the air cleaner I used. There are hundreds of different configurations for mixers from 1hp up to 1600hp.

Here is a view into the top of the mixer...


This particular mixer does not use any diaphragms, it uses a finely machined air gas valve assembly with a large spring underneath. The more you open the throttle plate, the more engine vacuum pulls on the valve and the more air and fuel is drawn through. As long as you dont smack it with a hammer, these will last 20+ years

Probably an over load of information but if you put it all together, it is actually very simple to work with. The regulator does the fuel control and the mixer mixes the air and fuel!

I will post some more pictures this weekend once I finish up my tank bracket.
 

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Wow.. That's very interesting!

When I did it to mowers (4HP Tecumseh and 6.5HP Briggs Quantum) I just connected the propane through the gas line and it worked fine.. Is this a bad idea? I don't think I harmed anything..

-Stan
 

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Great information. In addition to the build, can you tell us where the average tinkerer con find the parts to do something like this, and what the expected cost would be?
 

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Discussion Starter · #14 ·
Wow.. That's very interesting!

When I did it to mowers (4HP Tecumseh and 6.5HP Briggs Quantum) I just connected the propane through the gas line and it worked fine.. Is this a bad idea? I don't think I harmed anything..

-Stan
You didn't harm anything, its not the safest way to go though for you or your engine. The fuel being pumped in will have you running rich and lean depending on the load which in extreme situations can cause valve damage. Also if you shut it down and forget to shut the tank off, you can have propane being pumped out into your garage or work area. The regulators we work with shut off the fuel supply if engine vacuum is lost.
 

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Discussion Starter · #15 ·
Great information. In addition to the build, can you tell us where the average tinkerer con find the parts to do something like this, and what the expected cost would be?
I can link you to our store but I am not sure if I need a star or something to do so? We have a few hundred kits listed for small engines along with automotive and industrial applications.

The project I am working on is a bit different than what we normally work with, I just so happen to have these components so I used them. Most of the time we can supply a venturi adapter that sits between the carburetor and air cleaner. All gasoline carburetors will have a venturi cast or machined into them already, we add a second venturi for the propane/natural gas. These venturi adapters have been used for YEARS in industrial applications.


Here are basic installation instructions, you can see the simplicity.



This is a generator application but applies to mowers as well. Your gasoline carburetor still controls the fuel (don't need a custom governor) you just leave your gasoline OFF. When the engine creates vacuum, it pulls through the carburetor and through the venturi, the venturi creates a draw which will draw the fuel through, engine vacuum is already drawing air. The rich/lean idle and rich/lean power valve adjustments are on the regulator. This is the ideal route to go for a conversion, it is very easy and if you want to run gasoline, you just shut off your propane supply.
 

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I have to say I have always been curious about this, but never really checked into what was involved. Bravo for your thread! It has encouraged me to delve further into the subject. Lots of info out there. I appreciate you sharing your knowledge and project with us......very cool :cool
 

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I started working for a friend of mine who owns a company that does conversion kits on automotive and industrial applications. After I started working with propane for a while, learned more about it, I ended up preferring it over gasoline!

First off, propane does not go bad, you shut your engine down, let it sit 6 months, walk out and start it right back up, no fuel degradation.

Second, it is very easy to work with, a rich/lean idle adjustment and rich/lean full load adjustment, once those are set correctly, fuel and air are drawn to the engine upon demand. There are no jets to clog or float bowls to varnish or fuel pumps to fail (propane is stored under pressure, no pump needed), you can usually get around 10 years of use from the diaphragms in the regulators before a rebuild kit is needed which will run you round $30.

Third, propane is very clean, has very low carbon so the engine stays clean on the inside (although your oil will still breakdown from usage, it will not turn black, still looks the same when you drain it as when you put it in!) it is a superior fuel compared to gasoline when it comes to carbon footprint.

Last off, this will depend on where you are located, propane is generally cheaper than gasoline. During my mowing season, propane maxed out at $1.99 per gallon while gas got up to around $3.45 Depending on where you get your propane from, the quality may vary and you can have a loss in power/economy, fortunately where I was buying from,the propane was on par with gasoline and my usage was almost identical.

The cons of propane...

First is where you are located. Propane prices will vary up and down widely throughout the states, a few of our customers get propane for $0.47 per gallon, and others unfortunately pay $6.00+ for it.

Second, propane averages around 110 octane and will burn hotter than gasoline, if you do not set your rich/lean idle and full load adjustments correctly, you can burn up your exhaust valves.

Third, if you are running your engine in -15° or lower, you will probably need to heat your tank if it is small (20lb tank)
All excellent points and well backed up.

Keep us posted; this is quite foreign to me and interesting to learn about it! :cool
 

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I have to say I have always been curious about this, but never really checked into what was involved. Bravo for your thread! It has encouraged me to delve further into the subject. Lots of info out there. I appreciate you sharing your knowledge and project with us......very cool:cool
Yes, for sure this is a great lot of information coming from someone in the know. Thanks!

All excellent points and well backed up.

Keep us posted; this is quite foreign to me and interesting to learn about it! :cool
Agreed, excellent information all around about the conversion.
 

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Discussion Starter · #20 ·
Thanks again for the feedback, glad this is helpful to some people!

Little update on my tank mount and the other part of my project! Had to get the heater going in the garage today, not sure where you guys are but the temp here has gone from 40s-50s over the past week or two and dropped to the teens and we are expecting rain and single digits tonight, tomorrow isn't looking so good!


Got my angle cut to the length I need, holes laid out ready for drilling. This will tie into my frame for my tank bracket and push mower mount.


Bolted on with some fresh paint too! If I paint before I mount the angle it will help reduce rust between the two.


Brace welded in for the push mower pull bar.


Additional mounting location for the handle of the push mower for my application.


Didn't take as many detailed pictures as last time but this is after I got my angle squared up and attached to the pieces I mounted to the frame. I drilled my holes for the push mower to be adjustable for width and welded the metal onto the push bar for pulling with my riding mower.


I am excited to see how this does once spring shows up, if it works well, I will add another push mower to the other side.
 
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