f**king carburettors

[tanz-e]

does anybody know of a good gas specialist in melb?
i need somebody who can find that fine line of tuning a duel fuel carburettor to both fuels...

can anyone put me onto somebody???

[MyGQ]

You don't tune a carbie for Gas, the carbie acts as just a throttle body for LPG, changing any of the mixture settings on the carbie will do nothing at all for gas whatso ever

To tune the gas you need to adjust the mixtures on your LPG converter (if its impco you can only tune the Idle mixture on the Impco mixer).

LPG tunes you have to choose what you want the most power/economy on, gas or fuel, smart option is to tune it to run best on gas as it cheaper, thats how i had mine done

[tanz-e]

im aware of all of this.
a good mechanic will still be able to get both fuels running fairly well...
one will always be better than the other-gas, natuarally...
but the last mechanic i used did a shit job, therefore my car now stalls on petrol everytime i run it...
i have, in the past had it running almost the same on either fuel but that mechanic has since closed shop and changed owners.... (the guy who took over did the shit job!)

[steveoo]

Give Joel and James a call at PGS they did my car wonders i had the same problem as you.

[brad-chevlux]

Your problem is that petrol and LPG require very different ignition curves.

It really shouldn't be hard to get the mixture settings for both fuels right.
stalling on petrol will be an idle mixture issue with the carby, as the idle speed for LPG and petrol are adjusted with the same screw.
Generaly most of the cars i see with dual fuel issues run fine on petrol and crap of LPG as to many 'mechanics' seem to be afraid of LPG.

A simple stand alone ignition only ECU with switchable ignition curves will let you have the best of both fuels.


I know i didn't really help you with finding someone to tune you car.

[tanz-e]

Your problem is that petrol and LPG require very different ignition curves.

It really shouldn't be hard to get the mixture settings for both fuels right.
stalling on petrol will be an idle mixture issue with the carby, as the idle speed for LPG and petrol are adjusted with the same screw.
Generaly most of the cars i see with dual fuel issues run fine on petrol and crap of LPG as to many 'mechanics' seem to be afraid of LPG.

A simple stand alone ignition only ECU with switchable ignition curves will let you have the best of both fuels.


I know i didn't really help you with finding someone to tune you car.

this isnt true....
theres another mixture screw for the gas... located on ontop of the carby.
it has markings on it: L and R
Lean and Rich.
i think theres yet another on the converter thingie as well. (the thing with the water pipes in it that freezes over if ya dot have enough water in ya radiator.) but im not sure about that.
if i crank my petrol idle and get it to run alright, my gas idle will skyrocket.... atherefore you need to adjust sometrhing else to compensate... adjusting the mixture screw on the top of the carby does faaark all...... ive tried so many differnet vairiables that in the end i just decided its easier to get some othe bloke ta do it...

the carby got a full reco no more than a year ago so should be fine.
(how ever the stupid increased idle cam isnt tuning of wen it should be)

[MyGQ]

Your problem is that petrol and LPG require very different ignition curves.

It really shouldn't be hard to get the mixture settings for both fuels right.
stalling on petrol will be an idle mixture issue with the carby, as the idle speed for LPG and petrol are adjusted with the same screw.
Generaly most of the cars i see with dual fuel issues run fine on petrol and crap of LPG as to many 'mechanics' seem to be afraid of LPG.

A simple stand alone ignition only ECU with switchable ignition curves will let you have the best of both fuels.


I know i didn't really help you with finding someone to tune you car.

this isnt true....
theres another mixture screw for the gas... located on ontop of the carby.
it has markings on it: L and R
Lean and Rich.
i think theres yet another on the converter thingie as well. (the thing with the water pipes in it that freezes over if ya dot have enough water in ya radiator.) but im not sure about that.
if i crank my petrol idle and get it to run alright, my gas idle will skyrocket.... atherefore you need to adjust sometrhing else to compensate... adjusting the mixture screw on the top of the carby does faaark all...... ive tried so many differnet vairiables that in the end i just decided its easier to get some othe bloke ta do it...

the carby got a full reco no more than a year ago so should be fine.
(how ever the stupid increased idle cam isnt tuning of wen it should be)

first get your petrol mixtures right

Sounds like you have an Impco setup. that L and R on the top of the carby (thats the Impco mixer) adjusts the idle mixture, lean it out and it will slow down when switched to gas, richen it and it will rev higher on gas

the Impco converter has no mixture screws, Impco converters work on the same principal as an old SU carbi, no mixture settings in their diaphram. thats why load is hard to adjust on Impco.

[ANDREWGQ 351]

Thats not quite right, the impco 300A or similar mixer that most Impco systems use do have mixture screw on top. The L & R are for main gas flow for cruise/ top end supply not idle
There is sometimes a cover bolt on top of this screw, it is verticle and inside the mixer top body

To set

With the engine warm, make sure the idle cam on the carby is released set timming to 10 deg i think thats std. Set the petrol idle mixtures and idle speed on the carby, do this with the mixer on,
Then switch to gas turn the L & R screw to about half way, (this is about normal) then adjust the gas idle mixture on top of the mixer to set smooth running and speed.
Timming may then be able to be increased to around 13 deg to improve gas performance and still be ok for petrol, after any timming change idle speeds may need to be changed

hope this helps

[GUtripper]

I just had my dual fuel rig tuned at Auto gas Connection in Carrum Downs
http://maps.google.com/maps/place?rls=c ... 7907339141

They were great, i was referred to them off here, and would recommend them to anyone gladly.

I had the Holley truck avenger tuned and jetted, and the gas tuned (needed a new converter as it turned out too). It now runs great on either.

They took the time to answer my questions, showed me what/why, and charged a reasonable price too that i was happy to pay. AND they have a 4wd dyno, which (other than seat of pants) is the only proper way to tune stuff IMHO

[coxy321]

Your problem is that petrol and LPG require very different ignition curves.

It really shouldn't be hard to get the mixture settings for both fuels right.
stalling on petrol will be an idle mixture issue with the carby, as the idle speed for LPG and petrol are adjusted with the same screw.
Generaly most of the cars i see with dual fuel issues run fine on petrol and crap of LPG as to many 'mechanics' seem to be afraid of LPG.

A simple stand alone ignition only ECU with switchable ignition curves will let you have the best of both fuels.


I know i didn't really help you with finding someone to tune you car.

this isnt true....
theres another mixture screw for the gas... located on ontop of the carby.
it has markings on it: L and R
Lean and Rich.
i think theres yet another on the converter thingie as well. (the thing with the water pipes in it that freezes over if ya dot have enough water in ya radiator.) but im not sure about that.

Brad was refering to speed, not mixture.

Freezing converter means there's an air lock in the converter (in the water jacket), there's not enough coolant flow, its plumbed incorrectly, or you have a collant temp problem. Most likely the first one.

Spark plugs should run a gap suited to the type of fuel used, and also the correct temp range too. If you use LPG most of the time, gap the plugs to suit and vise-versa. I don't know too many workshops that gap plugs to suit specific fuels, most just replace the old ones without checking. Joel at PGS can help you with plug types and gaps.

[tanz-e]

thanks fellas

[brad-chevlux]

Your problem is that petrol and LPG require very different ignition curves.

It really shouldn't be hard to get the mixture settings for both fuels right.
stalling on petrol will be an idle mixture issue with the carby, as the idle speed for LPG and petrol are adjusted with the same screw.
Generaly most of the cars i see with dual fuel issues run fine on petrol and crap of LPG as to many 'mechanics' seem to be afraid of LPG.

A simple stand alone ignition only ECU with switchable ignition curves will let you have the best of both fuels.


I know i didn't really help you with finding someone to tune you car.

this isnt true....
theres another mixture screw for the gas... located on ontop of the carby.
it has markings on it: L and R
Lean and Rich.
i think theres yet another on the converter thingie as well. (the thing with the water pipes in it that freezes over if ya dot have enough water in ya radiator.) but im not sure about that.
if i crank my petrol idle and get it to run alright, my gas idle will skyrocket.... atherefore you need to adjust sometrhing else to compensate... adjusting the mixture screw on the top of the carby does faaark all...... ive tried so many differnet vairiables that in the end i just decided its easier to get some othe bloke ta do it...

the carby got a full reco no more than a year ago so should be fine.
(how ever the stupid increased idle cam isnt tuning of wen it should be)

idle speed for both is adjusted by the idle speed screw on the carby.