LPG kit help, again????????

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marcjagman
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LPG kit help, again????????

Post by marcjagman »

I have a 3.5 on carbs and am thinking about fitting LPG, whilst the car is still "in bits" it seems to make sense to do it now. As I am unable to work for a living I will probably have to buy the bits one at a time as I can afford them, at least I'll be able to buy the bits I prefer. I have been reading a lot on the subject but still hesitant. Is there a site somewhere with a simple diagram on how to fit an LPG system? I roughly know all the bits I'll need, tank, filler, vapouriser, valves, etc but still not 100% on how/where to fit, probably due to me not liking things I've not done before. They are probably easier to do than I think and reading the comments on here, they are. My main questions are, how does the gas get into the engine from the vapouriser, is that what one of the valves is for? Not really looking for a step by step just how it goes together and works under the bonnet. Thanks in advance.



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Post by Quagmire »

We have three v8 (carbed) Landrovers in my family, all running lpg. The setup is simple, and although it may be more tricky to mount it all in a "normal" car the principles are the same. :D

The system that goes from one end to the other it goes like this.

Filler -> pipe (carrying liquified gas) -> tank

tank -> pipe (carrying liquified gas) -> vapouriser -> pipe (carrying gassy gas) - mixer rings.

On my 90 I have the tank in the rear loadbay, tight against the rear bulkhead (so right behind the seats). The pipework exits the tank through the floor, with one pipe running to the underside of the rear crossmember where the filler point is attached. This means the filler is in the centre and I can use pumps on either side. :wink:

The other pipe runs forward to the engine bay, staying well clear of rotating/moving parts and hot bits. It needs to be clipped every 30cm.

This pipe connects to the vapouriser which is where the LPG is... vapourised! This then has a pipe running out of it to the mixer rings, feeding them LPG in gaseous form.

I have SU's and the mixer rings are sandwiched between the carbs and the elbows that connect to the airbox:

Image

You can see the feed of gas coming from the top of the vap unit at 10 O'Clock and then splitting off to each carb. The valve you can see on that pipeline is the power valve (also called the economy valve) and this is usually used to adjust the mixture at revs.

The vapouriser needs to be connected to a supply of engine coolant in order to keep it warm and prevent it freezing (I once measured mine with an infrared thermometer from a cold start and it quickly went down to -18C...). On mine the water connections are Teed into the heater circuit at the rear of the engine. In the pic the pipe at 12 O'Clock on the vap is one of the water pipes.

In terms of electrical stuff if you have an open loop system it's pretty simple- You have three solenoid valves on the gas lines, one on the tank itself, one before the vapouriser and one on it. You may also have one on the petrol line, although I have a switch on my fuel pump that I just turn off when appropriate...You also have the tank level sender wiring to route back to the switch.

The LPG switch will have a safety built into it whereby it will need to know if the engine is running for it to keep the valves open. This usually requires a wire run back to it from the coil negative or I believe you can run a wire to the king lead on the dizzy and wrap around it a few times.

Then the only wiring left is ignition switched live and earths I think...

Good people to talk to are Tinley tech- have a google. They are very helpful.

Hope that all made sense!
1974 Rover 3500s
1984 3.5 90
1959 2.25 series 2

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Post by ChrisJC »

:whs :nw :racing

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Post by marcjagman »

Is it really that simple? Sounds and looks straight forward, always wondered what a mixer ring was, now I know. Why 3 solenoids? Can understand one on the tank, stops the gas when on petrol, does the one on the vapouriser come with it? And why the third? The picture and info was very useful.

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Post by ChrisJC »

The solenoids are safety devices, something you can't have too many of on a pressurised system!

You really need to get your vapouriser and mixer rings as a matched set. I have tried mixing and matching from different sources before, and had real trouble getting the mixture about right.

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Post by bobtail84 »

I may still have a vaporiser, rings "Y" piece and other bits for twin strombergs in the shed. I'll have a look if you like.

Jeff
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Post by marcjagman »

bobtail84 wrote:I may still have a vaporiser, rings "Y" piece and other bits for twin strombergs in the shed. I'll have a look if you like.

Jeff
Thanks very much, that would be great. Using Stromberg CD1.75 carbs.

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Post by bobtail84 »

marcjagman wrote: Thanks very much, that would be great. Using Stromberg CD1.75 carbs.
I will look tomorrow and take some photos.

Jeff
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www.essex-ms.co.uk

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Post by marcjagman »

Any joy on the LPG bits yet bobtail?

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Post by bobtail84 »

marcjagman wrote:Any joy on the LPG bits yet bobtail?
I've found the vaporiser but I'm still looking for the other bits. Typical, I've been tripping over all the bits you need for ages but try and find them when you want them... :roll:
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