guys anybody that can help me find a propane conversion kit or tell we what all i need to do for a 1984 Ford F250, with a 460 4 barrel carb., i would appreciate it the carb is gettin bad and with gas prices propane is much cheaper then gas, im tryin to talk to some old timers about propane conversion but so far havent got any info yet.

 

Saw one on eBay the other day....

 

theyre around here all the time for a couple hundred bucks...or with a complete truck for a couple hundred more.
Theres nothing fancy to getting the engine to run on propane. You need the tank, the line, the vaporizer/converter, another line, then the mixer.
Not sure if you need an adapter for the 4v flange or not. I think all the bigger mixers are for 4v carb replacement anyways, dont quote me tho.
I shot you a pm with a link to a propane forum, very knowledgeable people on there. Check it out, search around it, post some Q's.
The converter uses a line tapped into your coolant to heat the propane and vaporize it before being induced into the intake, so the expansion of the fuel vaporizing doesnt displace and oxygen (it expands 270x its size from liquid to a gas).
There are plenty of places that sell conversion kits, just search the web....but start on that link I sent you.

 

thanks for all your help guys its greatly appreciated, maybe i can finally get a propan kit and be able to afford to drive my pickup

 

Do you know for sure it's cheaper to drive with propane?
The fuel is cheaper than gas (I belive it's around $2/gal), but maybe it gets worse mpg. Kind of the inverse of deisel.... fuel costs more but gets better than mpg.

 

From what I've read most vaporizer/mixer (carb type) setups get around 80% of the mileage on propane than what they get on gasoline. If you up the compression ratio to around 12:1 they will get the same kind of mileage on propane that they did on gasoline - but then you can't run gasoline in them any more 'cause even running "premium" 92 octane gas they will ping too much.

 

well even if it does not get as good of mpg as with gas, it cant be to much worse scince i get no more then 10 mpg with gas, so im going to try it but i will have it set up for dual fuel, with the propane and the gas jsut a switch that u have to flip to change it.

 

Try this forum.

 

you can build your engine to run on propane and get better mileage and more power than with gasoline. The stuff is 104 octane...thats like race fuel octane. It has less BTU per unit than gasoline, thus doesnt expell as much energy...therefore requiring more to get the same. Which is why you loose some mileage, generally you get about 80-90% of the gasoline MPG on a direct swap over to propane. 11:1 is a fair streetable compression level easy enough to tune for...getting higher than that takes extra attention in the tuning. The higher compression allows for better VE, making the most out of the energy potential, which is where you can make up the mileage and power loss....
As far as cheaper, it definately is. Where I live, gasoline is $1.00/liter. Propane is in the 50 cent range, sometimes low 60cents...we will say its 60 cents a liter for comparison. The cost is 60% of gasoline...to equal the same mile per dollar you would have to get 60% of the mileage on propane that you would with gasoline. That is not the case tho, you get 80-90% the mileage...thats a +20% mile per dollar increase. Make sense?

now build the engine specifically for propane, and say you get the same mileage. Thats a 40% increase of miles per dollar over gasoline.
To build an engine to run strong on propane you want to pay attention to cylinder pressure. Keeping it high will net you the best results. You can run 11:1 compression with a crappy cam that lets out all the cylinder pressure and end up with an engine that performs worse than a 9:1 engine with a proper cam to keep those pressures up.

Im no cam whiz, im still learning about them. There is a difference between compression ratio and cylinder pressure. Valve timing/overlap is the key there. This is why propane engines run exceptionally well under boost.

Making your truck dual fuel compatible will mean youll have to sacrifice propane performance, or run on premium fuel. There is a tradeoff, you can only have the best of one world there...hmmmm.....unless you turbo it and run an electronic adjustable BOV and turn the boost way down when you run on gas, then crank it up for propane...

460k&n search through that site, the admin there posts on here as "fraso" also.

 

Ford has cams and heads made for propane.I have two trucks that run on propane.they are stock other than the propame parts .My 87 F250 has a 460 and gets 12 miles a gallon .My 89 F350 4X4 gets 8.7 miles a gallon.

 

Does anyone have good cam specs for propane? I know that each engine will be a little different. I have a 351M. But I am looking for good specs. I am planning on rebuilding the engine with 10.5:1 to 11:1 compression. The 335 engine forum likes the Comp Cam 255 for RV/Towing application, so that is where I intend to start, but I think I have to increase overlap to keep the exhaust valves from overheating. Can this be done without sacrificing dynamic compression ratio?

 

fuelsforum (dot) rasoenterprises (dot com)
the guys there may not know what cam will be good for your specific engine, but they will help you find what youre looking for.

 

You might want to check out www.propaneguy.com and www.autopropane.com for some info. From my experiance with gas trucks duel fuel setups can be a pain.some work great.

 

1978crew- all you really need for a cam is as the 335 forum guys said... a good rv cam with a 6 degree bias towards the exhaust, and make sure you replace the valves with good stainless steel ones

 

What do you mean by "bias toward the exhaust?" 335 engine forum recommends the Comp Cam 255 cam but i do not understand all of the cam numbers. I think most cams call for 110degree separation. should I close the gap by 6degrees?