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The Other Greg

1980s S1600 propane engine- gasoline convesrion?

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Hello,  I am still searching for a truck for my property to haul water and dump runs local etc. Every month or so. I have run into a 1981 S1600 in acceptable "pre beater" condition that runs on propane for under $1000. I have yet to take a look as it is under snow but it has a 23,000 GVW, flat bed dump, 5-2 trans, and I think a 346 engine. The front brakes have blown a line and needs to be repaired, there is typical rust in rockers and was at one time a lumber yard delivery truck. Drivers rockers are rotten and will need replacing- any sources for these?- have MiG ready to weld.

The sticky part is the propane. The tank drain is stuck- not allowing the tank to be refilled. I know nothing about propane powered vehicles and need more information here from the experts.

I have read about performing a propane back to gasoline conversion. My local IH guy says "big bucks" but he always says that. I am thinking also of perhaps an injection vs carburetor upgrade? Maybe even a DT conversion- from a former school bus? I dont know. Not looking for a huge complicated and expensive project but have mechanical skill to perform intake manifold, wiring and engine swap if necessary. 

Opinions and information please! Many Thanks. Other Greg,

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Intake will be the same as a gas engine. If its a factory conversion it might be really high compression ratio. I would find a good propane tank.

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Can you post pictures of the engine? It's probably a 404 or a 446.

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you would be money ahead, to just fix, or replace the lp tank. contact your local lp supplier, they may be able to assist you. heck they may even have a tank just like you need.

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Valves can be easily changed out on L-P tanks-------or find a replacement tank.

The L-P fuel system is pretty simple----once you get a base understanding of the principle.  Seems like 90% of any L-P engine issues are usually ignition related.  Ignition needs to be "spot on" (hot).

I have a F-700 with factory propane 429 engine--------lots of power.

Factory propane engines had higher compression ratios vs gasoline engines so to compensate for the energy loss from L-P vs gasoline.  (theoretically balance power with both fuels)

Converting the high compression engine over to gasoline would most likely require running high octane gas----even more expense.

Good luck.

 

DD

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Here are engine pictures- unsure of mileage, engine type/size or condition.  What do I have here? Could you propane power experts walk me through what is what? Thanks Greg

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That's a 345 with a Holley 2 barrel bolt pattern. A Holley or Autolite carb bolts right on. The fuel pump attachment point will have a blockoff plate on it. There might not be an eccentric om the camshaft to run the pump, if that is the case an electric pump will work fine, the advance in the distributor should be swapped for one from a gasser but it will work in a pinch. Strap a gas tank on the frame rail, dump the propane stuff, and you're golden!

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The propane carb is located in the std carb position.  Attached to the carb is the regulator.  On the firewall appears to be a fuel lock device (I don't use those, they are for safety). 

Try hooking up the propane bottle from your bbq grill to see if it will start.  Your propane supplier should have the fitting that will hook it up to the hose.  I use the small tanks to test propane motors, they work fine but not long.  

Thx-Ace

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Thanks for the help so far you guys are great!

So things to think about..

Needed (for propane to gas conversion): a carb, elec. fuel pump, gasser distributor, gas tank lines etc.

Not needed: Intake manifold

How can I identify if the engine has the factory propane and indeed has a high comp ratio? Codes on the outside? Glovebox card?

Also: How hard is installing a new front brake supply line? owner says he blew it (rust) and truck has no brakes currently.

 

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606912754_IHCtruck_propane.jpg.ca292c692151fa0025c63db83a5779f0.jpg

 

The propane set up looks similar to what I have on my Ford F-700.  The Impco model 425 is a popular and dependable vaporizer for those size engines.

I have identified the different items in your picture.   Really don't know if this was factory or not????

Liquid pressure line should run from tank to the safety shut off switch;  and pass on through to the inlet connection on the vaporizer/regulator.  The vaporizer has coolant hoses attached so to heat and vaporize the liquid to vapor which passes through the elbow and into the mixer.  The vaporizer also acts as a pressure regulator-------cutting the high pressure down to low pressure vapor.   The mixer acts just as a gasoline carbruretor--------mixing air and gas.

The safety shut off solinoid is designed to cut the high pressure flow from the tank in case of a wreck, etc. .  It is electronically actuated from the ignition switch.   I agree with Acem on the safety valve-----------I have by passed (done away with alot of them).  Just connect the pressure line from the tank directly to the inlet on the vaporizer.   I have had lots of trouble with the electric solenoid not opening-----------and cutting gas flow off.

Good advice from Acem on connecting a small propane bottle directly to the inlet going to vaporizer just to see what you have.

Cranking process:

A.   Open valve at tank----------feeding line going to engine compartment.   Check for any leaks----------if leaking you should be able to hear or smell .

B.  Pressing the button on top of the vaporizer releases some raw gas into the mixer if needed for cranking.   That's also a good test to know you have vapor passing through the vaporizer---------you should be able to hear a slight blow when you press downward on the button.

And-----------a small shot of starting fluid might be needed.   Just don't over do it.

 

If getting gas to mixer and does not crank--------------check ignition.   Ignition is a key issue with L-P gas engines------you need a hot blue spark.

 

After you get it cranked:

1.  Adjust the small idle screw until engine idles at smoothest and highest rpm.   At this setting---------engine should crank near immediately when hitting starter.

2.   There is a load adjustment screw (larger screw with hex head) on front of mixer.   You need to set it for maximum power with a load on it.  Uhhh------along the lines of doing away with the safety switch;   I have ridden along adjusting on the load screw with a driver holding a steady throttle on the accelerator pedal.  You can get pretty close by setting the load screw while someone is holding the brake.

With everything set on the money--------------you should smell little to no propane out of the exhaust.

 

Everything is basically the same principal as with a gasoline engine--------other than you are operating with a different fuel source.

 

Good luck-----have fun.  Keep us posted.

 

Delta Dirt   Avon  Ms   38723

 

edit:  just thinking about determining whether factory propane or not;  see if there is a gas gauge in the dash.   I don't believe my F-700 has a gas gauge in the dash.

 

 

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Correction:  the factory propane F-700 does have a fuel gauge in the dash------same as gasoline model dash.  

But apparently never read the propane level.

So much for that theory.😨

Best to check the line set ticket if you can find it.

 

DD

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Delta gave you some great advice. Let me add some more.

Before you try to start it take the spark plugs out and squirt some oil in the cylinders. Then spin the engine using the starter for a min or so (be sure to leave the plugs out).  Then put the plugs back in to try and start it. This will help your compression at startup.

You can start and run the engine on propane vapor instead of liquid if it is warm outside (above freezing). Dad was having trouble with people stealing propane from the tanks for our irrigation engine so he removed the liquid valve and ran the engine on vapor. It works fine for me 30+ years later. I don't know how it would work in a northern winter though.

Thx-Ace

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I do not know if or where a copy of the lineset was attached in that truck.  If one can be found, the factory LP engines do have separate codes from gas engines.  A lineset can be ordered from the Wisconsin Historical Society or through Navistar dealers.  The engine size is stamped on a pad on the right side of the block next to where the fuel pump for a gas engine would be mounted.  I do not know if this included something to indicate an LP engine as I've never seen one.  If you get a chance to check, I'd like to know if it indicates anything.

SV-8 67 travelall engine motor number.jpg

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I own both an international "modified". irrigation propane engine in 304 and 392 size. they both read V 304 LPG and V 392 LPG where Howard described. I am assuming a factory modified 345 on propane would also read LPG there. I always assumed the factory LPG engines had harder valve seats also, being propane or natural gas was a dry fuel and the gasoline versions were made back when we had lead in the gas. 

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Thanks for that info.  I thought they would be marked, but didn't know that.

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Thanks very much for all of the super informative responses for this post. I know that the owner says the truck starts and runs like a top. the major concern is the lack of a functional front brake system (juice) and a way to verify fullness and fill (stuck vent) the propane tank. 

 

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Hi,

I don't mean to hi-jack the discussion, but can an engine be modified to run on both propane and gasoline with the ability to switch back and forth between the two fuels?  Perhaps stack the propane mixer on top of the carb somehow?  With the price of regular gasoline now over $4.25 a gallon in this city in California, the price of propane is still less than $2.50 a gallon.

Thanks.

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They made such a kit. I have not seen one for sale in a while. They mount on top of the carb and can supply propane or gasoline. electric solenoids select the fuel and a cable went to the propane carb as well. Dad ran one on a 78 1/2 ton dodge 318 for many over 100,000 miles.

Thx-Ace
.

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I ran a dual fuel setup on a Chevy full size van (80's model) with a 305 engine and put over 180,000 miles on the engine with no trouble.  It was nice to have the gasoline backup on long route days to get back to the plant and fill both fuel tanks.  The engine was torn down at that point and rebuilt because the entire engine was worn out EVENLY through the entire block and rotating assembly!  The clean burn of the LP gas lengthened its life substantially.

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The dual fuel set up never seemed to work that good on the fuel injected engines.

My son set a '94 model F-150 (5.0 engine?) up for duel fuel-------it just never worked quite right.  Finally removed it and ran straight gas.  And------we see very few late model p-ups burning L-P anymore.

We ran lots of dual kits on the older models with carburetor or throttle bodies.  Main problem would be not running enough gasoline through the carburetor often enough to keep carb from drying out.  L-P is dry in vapor form (as going through carburetor and intake).  And------having  dependable electric solenoids for switching gas on/off.

 

DD

 

 

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