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Discussion Starter #1
I've got a complete propane setup from a 78 that had a 460. Everything is complete. How many of you guys run propane and what is the tricks to getting it to run right?

My motor
428 cj
.030 over
10.5:1 compression

When i had my heads rebuilt I installed hardened exhaust seats and stainless cj valves. My head guy said that he found 10:3:1 to be the best to run propane. My motor is right there! He also said break in the motor on gas as the propane runs too clean. Motor now is basically broke in and I'm thinking propane could be a sweet setup.

Now will I lose power? I've heard that propane when used creates a perfect air/fuel ratio so if you had a carb not dialed in perfect going to propane some guys actually notice a power increase.
Major benefits are obviously the ability to run on any angle and it's cheaper

What about dual fuel? I've heard mix thoughts as the timing? Has to be set for a happy medium and isn't ideal for either. What's the best tips for setting it up. Do you just mark distributor for gas/propane and adjust for w/e you use. Correct me if I'm wrong

Is propane really worth the effort. Loss of power is a big concern. How much will it effect the performance? Thanks guys
 

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propane contains less energy than gasoline, so yes, there will be a slight loss in power no matter what. like you kinda said though, it's poor man's injection so you may feel a seat of the pants gain due to better response. allgonoshow recently went propane on his rig and said he'd never go back to a carb again. maybe pm him if he doesn't chime in. i've wanted to go propane on a rig for a while, but around here propane motor fuel is not common and refills would be a bitch to do, or i'd have to use grill tanks. you canucks are a lot more propane friendly though. personally i'd never run a dual fuel setup. from my reading on it, they seem problematic and like they'd be more trouble than they are worth.
 

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Horsepower Junkie
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I plan on running propane on my 460. Stock bottom end with some mild ported C9 heads, scorpion rockers. From what I understand (just research I'm new to LP also) your lower rpm range won't be hurt too much. (0-4000 or so) Beyond that a single 425 mixer just does not flow enough. Thus the need for either two mixers or the technocarb 750 cfm mixer. (expensive I hear). But if its ran on the trails how often will you hit 5000 rpms for long periods??

I think if I had a truck that was going to spin to to moon often or just mud run with limited steep angles I would stick to a gas carb. I will be running a crawler/ trail truck that will see steep angles and hill climbs often with a limited amount of high rpm bursts so I think it will work fine for me. If it just needs more later on I may run dual mixers.

Right now I am trying to figure out what cam to get to be more LP friendly or if I should just run the cam that would best match my setup if I was still running gas. Any advice?
 

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huff, just be warned, the only folks i know of making a non tunnel ram dual quad intake for 460's is blue thunder. i wanna say it cost like $600ish.
 

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Had propane for many years...it is very nice other than the inconvenience of having the tanks filled...hook up crank idle down to about 600 rpm and enjoy..pretty simple...With that motor you shouldnt notice the power loss it is only a few percent...only reason my buggy is getting fuel injection this time is because I couldnt fit my propane tank,radiator and fan in the back of my cage after narrowing the cage..
 

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propane contains less energy than gasoline, so yes, there will be a slight loss in power no matter what. like you kinda said though, it's poor man's injection so you may feel a seat of the pants gain due to better response. allgonoshow recently went propane on his rig and said he'd never go back to a carb again. maybe pm him if he doesn't chime in. i've wanted to go propane on a rig for a while, but around here propane motor fuel is not common and refills would be a bitch to do, or i'd have to use grill tanks. you canucks are a lot more propane friendly though. personally i'd never run a dual fuel setup. from my reading on it, they seem problematic and like they'd be more trouble than they are worth.
Propane is capable of making more power then pump gas in a properly setup engine. It contains less energy one to one with gasoline but you just run more of it to equal it out. Methonal and Ethonal are the same way. It just takes more of each to make the same power as gasoline does. It will support alot more compression the gasoline will.
 

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just get a 7.3 powerstroke and be done with it :flipoff2:
 

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Discussion Starter #10
Just pulled the system. Has 2 good sized tanks. Everything was in really clean shape and hose fittings came off with no issues. The mixer is a impco 425. Not sure about size yet with this motor
 

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Horsepower Junkie
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The 425 flows 450 CFM. Go figure. I would have called it a 450.
 

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Pane is awesome, better response, doesn't go bad, doesn't gum up stuff if it sits in the tank for a while, runs at any angle. I'll be one of the ones that will never go back to a carb again.
 

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Discussion Starter #14
You'll love the propane. Only inconvenience is filling the tanks, remedy this by purchasing multiple tanks.
We have enough stations with propane around here it won't be too bad.
Now this setup has the mixer that bolts to intake. If I did go duel fuel would I need something that just sits on my carb. My carb is a 670 Holley truck avenger
Also just curious does propane change the sound of a vehicle. I run dual 40 flowmasters will it slightly tame the sound? Maybe a dumb question..
 

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Discussion Starter #16
I'm really liking this propane idea. Everyone seems to say good things!
 

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I'm still curious about cam choice. I know it will run fine with the stock cam but I'm changing the cam anyway. Is there any sort of rule of thumb when running propane instead of gas? I.E. run a bit more duration than you would with gas? Open the valves quicker? Or am I over thinking it? I haven't found much info on the cam yet. Could Proeliator or some of the other big block gurus chime in?
 

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I'm still curious about cam choice. I know it will run fine with the stock cam but I'm changing the cam anyway. Is there any sort of rule of thumb when running propane instead of gas? I.E. run a bit more duration than you would with gas? Open the valves quicker? Or am I over thinking it? I haven't found much info on the cam yet. Could Proeliator or some of the other big block gurus chime in?

The rule of thumb for cam selection (aside from the obvious ones dictating the power band the motor will be living in and component selection) is that when using propane versus gas you want to use a cam with a wider lobe separation angle and stick with one closer to a medium duration end of the spectrum. Also, use a single pattern over a dual. All things being equal, you will have power loss over gas (long ass thread in here somewhere where I went over the thermal dynamics of pane in a debate with a vendor)...however all things are usually not equal and unless your gas motor is set up optimally you probably won't see a loss. This is assuming that its not an all out performance motor, of course.

This information comes with a caveat that I have not run a propane bbf myself, but is just info I've gathered from reputable sources.
 
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