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Converting to petrol cos its cheaper than LPG?? 

 

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 Post subject: Converting to petrol cos its cheaper than LPG??
Posted: Sat Dec 15, 2012 11:36 pm 
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Hi guys,
OK as you may know I run my 351 on LPG only, and I have done since putting that engine in. When I first got the Fairlane the engine came out of, it ran fine on both petrol and gas but previously my car had only run on gas, so when I installed the 351 I only hooked the gas up - the petrol side of things hadn't worked in my car since I've owned it, like 12 years or something. Anyway, with LPG going up and up with the excise etc. its now at a point where petrol's cheaper (at least around Adelaide) if you use the `LPG more than 50% of petrol' rule. That, combined with my tank needing an inspection in 2013 anyway, is making me consider just pulling the gas system out and running it on petrol.

So....given that the carby (600 holley) ran fine on petrol 2 or 3 years ago but hasn't had petrol thru it since, do you think it'll need a rebuild, or just run petrol thru it and see how it goes? Obviously I'll need to pull out and clean out the tank, fuel lines etc but I'm just curious about what you all think about the carby...I will probably end up just running petrol thru it and see how it goes but yeh, just seeing what you guys think.

Also curious what other LPG users think generally about the notion of using petrol over LPG ..what are you thinking about the excise and pricing? Has it got to the point that there's no advantage to LPG?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Sat Dec 15, 2012 11:43 pm 
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tearlejc wrote:
Hi guys,
OK as you may know I run my 351 on LPG only, and I have done since putting that engine in. When I first got the Fairlane the engine came out of, it ran fine on both petrol and gas but previously my car had only run on gas, so when I installed the 351 I only hooked the gas up - the petrol side of things hadn't worked in my car since I've owned it, like 12 years or something. Anyway, with LPG going up and up with the excise etc. its now at a point where petrol's cheaper (at least around Adelaide) if you use the `LPG more than 50% of petrol' rule. That, combined with my tank needing an inspection in 2013 anyway, is making me consider just pulling the gas system out and running it on petrol.

So....given that the carby (600 holley) ran fine on petrol 2 or 3 years ago but hasn't had petrol thru it since, do you think it'll need a rebuild, or just run petrol thru it and see how it goes? Obviously I'll need to pull out and clean out the tank, fuel lines etc but I'm just curious about what you all think about the carby...I will probably end up just running petrol thru it and see how it goes but yeh, just seeing what you guys think.


Gaskets would of shrunk from drying out.
Will need a kit at least put through it.
LPG at the moment is expensive because its the Northern Hemispheres Winter and our price is set accordingly.
It will get cheaper over Winter.
Duel Fuel Style setups are always crap. Fit a 425 on your 600 baseplate and get the ignition curved for gas only and it will use less fuel.
Also curious what other LPG users think generally about the notion of using petrol over LPG ..what are you thinking about the excise and pricing? Has it got to the point that there's no advantage to LPG?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Sun Dec 16, 2012 12:03 am 
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agreed on rebuilding the carby, good idea.

LPG pricing, though....yes, I know what you are saying about seasonal price fluctuations but this excise is here to stay, and its only going to go up....believe me I'd love it to go back down so its cheaper than petrol but it just doesn't look like thats going to happen....

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Sun Dec 16, 2012 9:50 am 
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tearlejc wrote:
if you use the `LPG more than 50% of petrol' rule.


Does no one in Adelaide know how to tune LPG?


If the petrol hasn't worked in 12 years, you will not be able to just clean the tank. You'll probably need to replace it and the solid lines.


But you haven't posted the current costs of LPG and petrol in your area.
We are at 89.9 for lpg and $1.60 95 octane. At those prices it was still cheaper to run the AU on an old venturi style LPG system then it was to run petrol.

I don't see how you are going to get a 600 holley to out perform EFI when it comes to economy.
Personally I believe the money is better spent on a retest of the LPG tank and better tune.
What ignition system does the engine have? and is the timing curve setup for LPG?
What LPG system do you have?
what intake manifold?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Sun Dec 16, 2012 12:40 pm 
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Hey Ticky, thanks for the reply - you're in the gas industry, aren't you? OK, first this 50% thing...I don't know, i read that somewhere. I mean, I like using gas, its just all the negative crap I'm hearing about this excise etc...that and my tank coming up just got me thinking. I'm glad I can pick your brains on this issue...

OK, my setup is a 600 holley but with an old school Impco 300 ( you know, the setup that hangs off the side and sits over the rocker cover). I mean , it works fine and all but of course an injection setup would be very nice but I assume out of my price range. Car runs really nicely on it, economy seems pretty reasonable and if gas prices stayed where they are right now or a bit less I'd be happy to keep it like it is.

OK, prices in Adelaide - I just filled up at 76.9 although it has hit around the 80c mark for a while. Petrol has been up and down, around $1.60 but just then I saw it at 1.38.

You were hinting that the 50% rule is crap - what are your thoughts on a comparison of prices? What I mean is, what price would gas need to be compared to petrol price to work out to be the same mileage wise , i.e. at what point is there no point being on gas? Also, what are your thoughts from an industry perspective of the excise? Is there more on the way or are we at the peak?

Appreciate your thoughts....

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 3:11 pm 
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The excise is 2.5 cents per year until it reaches 12.5cents. It's currently at 5c and will be 12.5c in 2015.

From the feedback I get my customers are using on average %30 more LPG then they would use petrol, with EFI vehicles fitted with impco or venturi systems.
With carby engines the ratio favours LPG a little more as carbs just don't get the mileage that EFI, but it doesn't effect the LPG.
The break even point with my AU was when LPG was at 76c petrol had to be 24c/L dearer to end up with the same running costs. Any more then that was money saved.
If you are looking at petrol at $1.38 LPG at 80c is still a decent saving.


A 351 should have a 425, not a 300. If you decide to stay LPG find a second hand mechanical secondary holley base and fit a 425 straight to the base, the 300 through a full carb body like you have is not very efficient.

Then setting the correct advance curve in the dizzy will improve both power and economy if it hasn't already been done.

A carb base, impco425 and tank test should be able to be had for under $1000. Calculate the savings based on the %30 usage rule, you only need to save 19.32 a week to pay off $1000 in 12 months but you'll get ten years from the tank and easy 5 years from the 425 before it might need a $50 diaphragm.
Id'd rather spend the money on the gas system to save $1000-$2000 a year then spend money fixing the petrol and paying that extra in fuel. Petrol isn't going to get cheaper, it might fluctuate a bit, the trend will always be up. Just wait till gillard puts carbon tax on fuel. (cos we all know the mole will do it one day.)

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 3:15 pm 
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tickford_6 wrote:
The excise is 2.5 cents per year until it reaches 12.5cents. It's currently at 5c and will be 12.5c in 2015.

From the feedback I get my customers are using on average %30 more LPG then they would use petrol, with EFI vehicles fitted with impco or venturi systems.
With carby engines the ratio favours LPG a little more as carbs just don't get the mileage that EFI, but it doesn't effect the LPG.
The break even point with my AU was when LPG was at 76c petrol had to be 24c/L dearer to end up with the same running costs. Any more then that was money saved.
If you are looking at petrol at $1.38 LPG at 80c is still a decent saving.


A 351 should have a 425, not a 300. If you decide to stay LPG find a second hand mechanical secondary holley base and fit a 425 straight to the base, the 300 through a full carb body like you have is not very efficient.

Then setting the correct advance curve in the dizzy will improve both power and economy if it hasn't already been done.

A carb base, impco425 and tank test should be able to be had for under $1000. Calculate the savings based on the %30 usage rule, you only need to save 19.32 a week to pay off $1000 in 12 months but you'll get ten years from the tank and easy 5 years from the 425 before it might need a $50 diaphragm.
Id'd rather spend the money on the gas system to save $1000-$2000 a year then spend money fixing the petrol and paying that extra in fuel. Petrol isn't going to get cheaper, it might fluctuate a bit, the trend will always be up. Just wait till gillard puts carbon tax on fuel. (cos we all know the mole will do it one day.)


My thoughts as well.
I originally pulled the LPG off my Maverick with all the doom and gloom stories about it.
Didnt take me long to put the Jew Juice back on board.

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 3:33 pm 
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well there you go...I'll be sticking with gas by the looks....can you explain a bit more about the 425 - so, are you saying this goes onto the carby (i.e. straight above it?) or whan you are saying `carby base' as opposed to `full carby body 'you mean like just the lower section of the carb? Sorry I can't quite get my head around what you mean...you wouldn't have any photo's by any chance?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 3:52 pm 
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Basically you take the elephants truck setup off your original carby and through it over your left shoulder.
Remove the throttle body base from your existing 600 Holley and fit a 425 Impco mixer to it.
This is the 425 Mixer
http://www.ebay.com.au/itm/NEW-IMPCO-42 ... 27cdf65d3e

 

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xr6turnip wrote:
More people paid for a ride in a VT commodore then an AU Falcon so the VT is superior.
Based on that fact my Mum is the best around!

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 4:09 pm 
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EVL098 wrote:
Basically you take the elephants truck setup off your original carby and through it over your left shoulder.
Remove the throttle body base from your existing 600 Holley and fit a 425 Impco mixer to it.
This is the 425 Mixer
http://www.ebay.com.au/itm/NEW-IMPCO-42 ... 27cdf65d3e



I see...OK, if I was to fit this do I also need to change the converter to suit or would the existing one be OK?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 5:21 pm 
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Existing convertor should be fine.

 

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xr6turnip wrote:
More people paid for a ride in a VT commodore then an AU Falcon so the VT is superior.
Based on that fact my Mum is the best around!

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 5:49 pm 
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EVL098 wrote:
Existing convertor should be fine.



Cool! If I was to just bolt this on and hook it up I suppose I'd have to get the gas re-tuned? Like adjusted and so forth?

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 5:55 pm 
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tearlejc wrote:
EVL098 wrote:
Existing convertor should be fine.



Cool! If I was to just bolt this on and hook it up I suppose I'd have to get the gas re-tuned? Like adjusted and so forth?


Definately. Goes without saying.

 

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xr6turnip wrote:
More people paid for a ride in a VT commodore then an AU Falcon so the VT is superior.
Based on that fact my Mum is the best around!

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Mon Dec 17, 2012 8:22 pm 
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You can't use a vacuum secondary base with a 425, you need a mechanical secondary base from 650 or 750..

But yeah the 425 bolts straight onto the base plate with no carb body. you then fit a decent sized airfilter and the untrained eye wouldn't notice the gas at first glance.


Like this but please use a bigger filter.
Image

 

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 Post subject: Re: Converting to petrol cos its cheaper than LPG??
Posted: Tue Dec 18, 2012 10:57 am 
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Cool - thanks guys, looks like the way to go...always hated how the current setup hanging off the side of the motor looks...

 

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