Outer Limits 4x4 Board

Hi

I have just had a used LPG setup installed into my GQ. There is no cable to pull when changing over to petrol. Looking at the mixer I cant see where a cable might go to allow more air to flow when on petrol and I heard someone say that some work on vacuum.

By looking at these pic can anyone tell me how mine would work?

At the moment I pull the hand throttle out a little to stop it stalling at idle if I ever have to use petrol.

Cheers
Eric

theres parts missing from the bottom of the mixer

theres like a round disc with 4 wedges that raise the mixer base but i cant see it on that mixer

dont worry it aint needed it just makes the diafram last a bit longer

The thing that bothers me is it stalls on petrol at idle when I switch over.

So you dont think it is one that would have worked on vacuum?

The mixer is a COPY of the Impco 300A series 1&20....
The "lift for petrol" set up is MANUAL on these mixers and in your pic I can see all the nessecary bits are there for the lifting operation but for the actuator slide plate...... its missing !

The lift plate is designed to manually open the thing when on petrol ..... some engines have enough engine vacume to do this and therefore dont need the manual cable or as in other systems the vacume lock which lifts and holds the plate up.

Obviously the engine vacume you have isnt enough to lift the plate so its not getting the right mix of air / fuel when on petrol..... wreckers will have the slider plate, at a guess an Impco one should fit....... I have a dozen odd here if all else fails .....
V8's dont need em


QUESTION.............

You said you'd just had it installed...... by whom ???? if it were a qualified fitter then it should be running well on both petrol & LPG.... in which case TAKE IT BACK ! ....... there is obviously a need for a far better tune up to be done !

Kingy

Cool, the gaskets seem average. Could that cause a lack of vacuum?

I had it installed by my mechanic and then certified by a gas fitter.

I was waiting to tune it because I have to enclose the air filter.

Thought it would be better to wait after I had done that.

The plastic surrounds you can buy for these dont look like they would seal well at all. I am just trying to work out how to build one that lets me change the air filter easily

Cheers
Eric

V8Patrol wrote: Obviously the engine vacume you have isnt enough to lift the plate so its not getting the right mix of air / fuel when on petrol.....
Kingy

I dont know about that. Mine works on vacuum and all is fine. Its a TB42.

rOd wrote:

V8Patrol wrote: Obviously the engine vacume you have isnt enough to lift the plate so its not getting the right mix of air / fuel when on petrol.....
Kingy

I dont know about that. Mine works on vacuum and all is fine. Its a TB42.

Does your mixer look the same as mine?

rOd wrote:

V8Patrol wrote: Obviously the engine vacume you have isnt enough to lift the plate so its not getting the right mix of air / fuel when on petrol.....
Kingy

I dont know about that. Mine works on vacuum and all is fine. Its a TB42.

Some do some dont...... dont ask me why as I have no idea

I've got three 253's here and all are on LPG using the same Impco setup, yet one of these motors will not run on petrol without a plate lifter, even tried to swap the mixers / converters around but with no success.
One of the 308's needed to be lifted if it was a cold start on petrol but didnt need it if the motor was warm
The 350 on the otherhand has never needed it at all
The commodore has a "new generation" setup and its vacume operated, again when its a cold start on petrol it needs to be lifted yet when its warm it doesnt need the vacume setup at all

Ive asked the fatherinlaw previously about this drama and he has no real answers as to why exactly either, he's fitted hundreds of LPG systems and has found as I have that some need it while others dont.

What about if I just get you to pop a 308 into my SWB then prob fixed?

an injected 308 ?????

Cool

After putting the mixer back together and I also had the fuel tank out to fix the sender the car now idles on petrol.

One thing different that I did do what seal around the pick up and the tank a little better.

Does one of the hoses on the tank have anything to do with vacuum?

EricB wrote:

rOd wrote:

V8Patrol wrote: Obviously the engine vacume you have isnt enough to lift the plate so its not getting the right mix of air / fuel when on petrol.....
Kingy

I dont know about that. Mine works on vacuum and all is fine. Its a TB42.

Does your mixer look the same as mine?

similar in appearance, but mines an impco.