305 on propane getting 4 MPG

[LPGbody]

Hey,
Just bought this 1981 C10 with a propane built 305. High lift cam, holley street dominator intake, impco 425 mixer, model L vapourizer.
I fill the tank up to 80L (20 gallons) and I go through it in about 4 days of driving, about 130 km (80 miles). I've fixed all the vacuum leaks and have verified there's no mechanical drag. the engine fires right up and runs very well.

I'm running 30x9.5 tires and I drive very conservatively. I'm honesty at a loss.

 

[LPGbody]

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[bucket]

So I assume that's bad? Lol. I have no idea what kind of mileage should be expected from propane.

Too bad @shiftpro doesn't seem to be posting anymore. He knows a lot about running propane.

 

[Ricko1966]

Check btu gas vs propane to get your gas mpg equivalent. I'll find it. K took a screenshot for you the discrepancy power wise is 27% Now take into account maybe a not professional job or needing some tinkering we change that 27% to say maybe 40%. 4x1.40 = 5.6. Yea still pretty low but a 305 with a big cam and I'm assuming an open plenum manifold is not going to get good gas milage. Make sure your vacuum advance is hooked up and working,make sure the centrifical advance is working,and learn how to set timing that your vehicle needs. It's a 305,with a cam,a different carb,a manifold and different fuel. You are going to have to figure out what the engine needs for timing,not what a stock 305 times at. Also if you read that screenshot,notice propane has a higher octane rating,meaning you could run more compression to make more power . A big cam lowers your dynamic compression.

 

[Turbo4whl]

As Rick stated you can not calculate your miles per gallon. Your tank may have a 20 gallon capacity but in the USA propane is sold by weight. Also the amount you receive varies by temperature.

You need to calculate miles per dollar. Compare that to a gasoline vehicle.

That tank probably equals 12 gallons of gasoline as far as range is concerned. You need another or bigger tank to increase your driving range/ fill up intervals.

 

[Turbo4whl]

One more thing about buying propane as a motor fuel. The government adds a motor fuel tax, per gallon. The metered fuel propane needs to be taxed. Since the price is by weight, the fueling meter will show a calculated gallon amount so it can be taxed.

 

[sidschev]

One more thing about buying propane as a motor fuel. The government adds a motor fuel tax, per gallon. The metered fuel propane needs to be taxed. Since the price is by weight, the fueling meter will show a calculated gallon amount so it can be taxed.

so now you know not to buy it for motor fuel if asked just say it fer your rv hookup screw gooberment

 

[Turbo4whl]

so now you know not to buy it for motor fuel if asked just say it fer your rv hookup screw gooberment

The problem is the retailer knows they are supposed to charge the motor fuel tax. More or less a dead giveaway if you pull up to the dispenser and say fill it up.

I would believe most retailers will not chance getting a big fine and maybe loosing the right to even sell propane.

 

[bucket]

The problem is the retailer knows they are supposed to charge the motor fuel tax. More or less a dead giveaway if you pull up to the dispenser and say fill it up.

I would believe most retailers will not chance getting a big fine and maybe loosing the right to even sell propane.

I'm betting if you go to places like Tractor Supply, they don't know the difference and fill it for the normal cost?

But now I have other questions. The tax would just be for road going vehicles, correct? Not things like forklifts? What about farm use vehicles?

 

[Turbo4whl]

I'm betting if you go to places like Tractor Supply, they don't know the difference and fill it for the normal cost?

Well if you brought in an empty can and took it home to fill your truck, they would not know. That would make you liable for the tax. Again fines etc.

But now I have other questions. The tax would just be for road going vehicles, correct? Not things like forklifts? What about farm use vehicles?

So you have a diesel fork lift, yes you get home heating oil and fill you fork lift. Home heating oil has a red dye in it. Put some in your road vehicle and it coats the fill and tank. Same for you propane fork lift, okay if it is not on the road. People go to jail for tax evasion if they get caught.

I realize the OP lives in Canada, I don't know what they require. Many people may not know there is the red dye in home heating oil. You open a fuel fill on a truck that has had heating oil at one time, you will see a pink color on aluminum. Looks more red on steel.

 

[bucket]

Well if you brought in an empty can and took it home to fill your truck, they would not know. That would make you liable for the tax. Again fines etc.



So you have a diesel fork lift, yes you get home heating oil and fill you fork lift. Home heating oil has a red dye in it. Put some in your road vehicle and it coats the fill and tank. Same for you propane fork lift, okay if it is not on the road. People go to jail for tax evasion if they get caught.

I realize the OP lives in Canada, I don't know what they require. Many people may not know there is the red dye in home heating oil. You open a fuel fill on a truck that has had heating oil at one time, you will see a pink color on aluminum. Looks more red on steel.

I meant a propane forklift or an old propane tractor. Not road going, but they also aren't a travel trailer with a furnace.

What I meant about places like Tractor Supply is the workers may not even know there should be an additional tax. There can't be very many folks that drive their old pickup to Tractor Supply and tell them to fill 'er up.

 

[LPGbody]

Hmmm well thanks for all the help and advice guys.

I'm a diesel guy at heart, my daily is a turbo diesel 4runner. So I'm used to getting 25+ mpg hahahaha.

I'll try and find a bigger tank, this is the parts runner so I plan on taking long road trips in it.

Might even try and find a 6.2 to drop in here...

 

[Turbo4whl]

I meant a propane forklift or an old propane tractor. Not road going, but they also aren't a travel trailer with a furnace.

What I meant about places like Tractor Supply is the workers may not even know there should be an additional tax. There can't be very many folks that drive their old pickup to Tractor Supply and tell them to fill 'er up.

I did understand. I posted a real world analogy using heating oil as an over the road fuel. Since there are a lot fewer propane units, no real way to check where the operator got the fuel. But big brother is watching!

 

[Ncali]

I had that same setup in a 73 long bed. fuel mileage was never better than 10
mpg. dont let your radiator water get low, the system will freeze up on you