Propane to Gas conversion on JD 4020???

[bbriscoe]

I have a John Deere 4020 that runs on propane - however, a new radiator was installed so there are no tank shutoff rods going into the cab. The tank seems to leak propane anyway and I don't have a good method to refill it.

Therefore I'd like to convert to a gasoline engine. What would I need to do this?

 

[Mace Canute]

I suppose the best bet would be to find a gas 4020 (complete as far as the fuel system goes) that you could get the right parts off of. Maybe check out a tractor wrecker or? Take LOTS of pictures of yours to show every little detail and then go look at the gasser and buy everything that you don't have! Maybe even buy the whole tractor if the price is right. There's lots to be said for that from the convenience point of view and time wise also.
Sorry...can't really make any recommendation other than this...:confused3:

 

[PILOON]

Never converted a tractor but we did convert a Clarke airport baggage tow tractor.

We simply removed and tossed the propane carburetor and went to the scrap (sorry auto recycler) and installed a carburetor that matched the intake flange being careful to select something in the same cubic inch range.
Other than gas tank and plumbing , the conversion went quite well.

 

[Cami]

I don't know your engine...

Most propane engines I've come accross were originally gasoline engines that had a mixer thrown on top....but if it was an engine specifically built to run on propane then it might have a higher compression ratio and cam suited to get the most out of propane fuel.

An engine like that might not take well to a gasoline diet.

 

[Mace Canute]

4020 LP models are supposed to be 9:1 and the gas models are supposed to be 7.5:1.

 

[77bronco]

You would probably have to use a higher grade of gasoline, but cars seem to run fine on regular with a 9.5:1 ratio.

 

[ModMech]

Typical modifications for LPG use include:
- More initial timing advance
- Lower total timing advance @ full throttle
- Colder spark plugs
- Colder thermostat
- Higher compression ratios (although not always)
- No manifold heat (intake)
- No choke provisions

To convert FROM LPG, there are a number of things to consider and I've done this a number of times on various makes.
- New distributor, or at least having the OEM one checked agains the specs for that engine in gasoline and adjusted accordingly.
- Use gasoline timing advance
- Hotter plugs (maybe a range or two colder then the gasoline plugs considering the higher CR).
- Add the correct intake w/manifold heat. I got tripped up big time on this one, yes it DOES matter. A gasoline engine won't run well at all, even warm, w/o manifold heat of some kind.
- Adding the carburetor and choke parts (fuel system).