Propane Conversion - '71

[Jeff10]

Hi Everyone,

We finally are getting some seat time in the Bronco after the propane conversion. I thought the whole process was going to be a lot easier... or at least a lot more straight forward.

We have had the Bronco on some moderate trails (Fins-n-Things and 7-Mile Rim) and on the city streets and some highway... all around Moab. So far, so good. (Actually it is great compared to the gasoline setup.)

TwoDalesDad asked for a rundown on the setup in another thread, so I thought I would start a new thread. I am going to include some pics, although they aren't the best.

Without getting into too much detail on this first post, I'll just include the basics. I'm happy to share what I know, so feel free to ask any questions.

Because the '71 is street-legal, we needed to make sure that the tank installation was legal, too (in conformance with NFPA 58). The tank is a manifold type with a vapor box. The vapor box provides a seal around all of the valves. The vapor box is connected to the exterior through the bed of the truck (actually the roll bar support plate), so any leakage into the vapor box exits through the PVC arrangement shown in the picture. (Propane is heavier than air, so vapor will fall to the lowest point.) The tank and valving were the most time consuming part of the whole process.

The fuel system is set up to run propane only. (There are options to allow you to run either gasoline or propane by operating solenoids for either the gas system or the propane system; but, I really didn't want to bother with the gasoline. For example, the plugs I am running are 1 range colder with a gap of 0.030" which works well with propane. If we were running dual fuel, the plug gap would probably need to be wider.

I am going to run out of room in this message, so I will keep it a little short. Please let me know if you'd like more details.

I found a used tank (after looking hard for about 3 months). (I was even looking for new tanks; but, the lead time was long, the cost was really high, and I never could get the manufacturer to provide the proper design that would work in the bed of the Bronco.) I bought the carburetion kit from Cary Gleason at GotPropane. And the most difficult part was finding a propane dealer that would work with me on the components I needed for the tank and filling system. Wholesalers of propane equipment won't won't sell to independents because of liabilty. I spent more for the valves and hoses than I did for the tank.

I have 6 months of experience making this all come together which is far too long. I'd be happy to share any other information if anyone is interested. I hope the first pictures are clear enough.

(The pictures in this first post are of the remote fill connections and the tank (and the vapor box/piping through floor). I will post another message with pictures in the engine bay of the carburetion equipment.)

Take Care

Jeff

 

[Jeff10]

Hey Again,

Here are the pics of the carburetion system in the engine bay.

Thanks

Jeff

 

[shamu]

Nice work. How many lbs of propane do your tanks hold?

 

[maverickconner]

What type of milage and what do you think the range is? How is the response versus gas?

 

[Gray035]

So what's the ballpark cost of a setup like this?

 

[Jeff10]

Hi Hopper,

Nice work. How many lbs of propane do your tanks hold?

Thanks for the compliment.

The tank holds almost 27 gallons water capacity, which works out to just a little over 21-1/2 gallons of propane.

Thanks

Jeff

 

[Hemi]

I owned a propane company for years. If you need any help, just ask. Keep a rebuild kit for the 425 carb and model E vaporizer. With practice you can rebuild both in 10 or 15 min as long as you can get at both sides of your vaporizer.

 

[Jeff10]

Hi maverichconner,

What type of milage and what do you think the range is? How is the response versus gas?

I have only run a few days on the setup. I'm not sure what the mileage is... the speedometer has never been set up for the current gearing.

The rule of thumb is that propane will result in about a 10% drop in mileage.

I used a little over 10 gallons with some city and highway driving, and two different trails over the course of 1-1/2 days. I'm hoping that we can get a couple good days of trail riding to a fill up.

I love the responsiveness of the setup. I have not changed the timing. The person who sold me the carburetion thinks that there may be performance improvement still laying on the table. I am most excited about the way the Bronco starts after shutting it off when hot... I just bump the starter and the engine fires. It is a great improvement over the carburetor I was running. I know that fuel injection provides a lot of the same benefits... I just like the simplicity of the propane set-up... no electronics of any type.

Take Care

Jeff

 

[Jeff10]

Hi Gray035,

So what's the ballpark cost of a setup like this?

The main consideration with cost is about use. Will the vehicle be used off-road only, or will it be used on and off highway? That makes a difference in the tank installation.

The location of the tank is also important. If the tank is exposed to the interior of the vehicle, technically there needs to be a vapor box and remote fill. That type of set-up can be expensive.

In round numbers, I spent about $150 on the used tank, about $950 on all of the carburetion, $150 to bedline the tank, about $400 on fittings, hoses, replacement valves, and remote fill hardware, and about $150 on other installation materials. If you can get away with using forklift (DOT) cylinders you can install the system for a lot less.

The manifold tanks with the vapor boxes, if purchased new, are probably around $1,500. Then you still need to buy all of the remote fill hardware.

I suppose a lot of the price depends on how hard you want to dig to look for used tanks or carburetion equipment.

Thanks,

Jeff

 

[Jeff10]

Hi Hemi,

I owned a propane company for years. If you need any help, just ask. Keep a rebuild kit for the 425 carb and model E vaporizer. With practice you can rebuild both in 10 or 15 min as long as you can get at both sides of your vaporizer.

How often do you find that the rebuild kits need to be installed?

Where are you located? My Dad was involved with propane when I was younger. Not many of the people that I knew are still involved. Thanks for the offer of help.

The only thing that I have left to tweak (after the transfer case is rebuilt) is to adjust the timing. The seller of the carburetion equipment thinks I should experiment with the timing. I am really happy with the performance at the moment, so I am weighing my options.

Thanks

Jeff

 

[Hemi]

Depends of the quality of your fuel and vaporizer position. As long as the diaphragms are intact, you can clean everything with carb cleaner. I found it best to mount it vertically. The wouldn't gum up as fast. There are two 1/4 inch bolt holes on the bottom for mounting. Plus you can get to the back diaphragm. I'm in so CA.

 

[TAC71]

Welcome to the to the other side. I have had propane on my Bronco for over 20 years. It makes driving a Bronco in Canada as a daily driver affordable. Gas prices here are about $6 a gallon, propane is about $3. With a capacity of 35 gallons I can go about 360 miles on the highway doing 75-80 mph. I do drive it all over the western states to go wheelin at Bronco events.
The best part is the ability to run practically upside down and run the rpm down to 300rpm without stalling.
Keep us posted on how its working for you.