LPG venturi conversion on a 19TZS

[Kevin B]

I am actively considering an LPG conversion on a BX19 TZS estate. This will be a budget conversion. I also intend to fit at the same time a manual choke conversion that I rescued from a scrap yard Peugeot 405 donor some time ago.

I already have an as new kit which I removed from a car that had being siezed for not having insurance, and was going to be squashed, this is the much simpler venturi type setup.

I am well aware of the insurance requirements an installation of this nature creates. New LPG components will be used where required ie new plastic coated liquid LPG pipe work from the tank to the vaporiser.

My question is has anyone had experience of a BX LPG carburettor conversion, and any potential pitfalls to avoid that could be expected.

Three problems I would particuarly appreciate answers to:

The vehicle to be fitted with this kit has a Solex carb, and I am struggling to find a suitable LPG venturi adaptor, I may have to splice a universal type into the rubber pipe between the carb and air filter but I am not keen on this idea.

I understand that should it backfire when running on LPG it can destroy the air filtration rubber and plastic pipework in an instant, what can be done to eliminate this risk.

The LPG liquid line from the tank to the vaporiser cannot be anywhere near the petrol line, on any other car not a problem however on a bx the next best position is where the front to back hydraulic pipes run. Any suggestion as to altenative positions

Any constructive advice on the above would be most welcome. Thanks in anticipation.

[AndersDK]

You will need a suitable venturi adapter. Alterenatively find a breakers carb that fits the adapter you have. Only concern would then be new gaskets. These should be easy to diy make from cardboard.

You will need to set the ignition timing a bit later (closer to TDC) to avoid backfiring. IIRC it should be reset to some 4deg from 8deg BTDC.

I have no idea on the requirements these days for the LPG piping, but would believe some kind of purpose made plasticide hosing is allowed.
Whats wrong routing the pipes next to the hydraulic lines ?
Should not be that hard to find any kind of standard hose clips that could be fitted using a screw/bolt from inside - lifting up the carpet.
Anything will do - as long as the piping is securely fixed with lasting materials.
Standard posters for nylon zippers will do neatly, but you cant use self adhesive types. Will have to be a screw-on type.
There is a large range of standard fittings available for small size electric and modern plasticide piping, which holds anything in the range of 8-20mm dia piping.
Have a look in your nearest DIY home&garden mart.

[Mike E (uk)]

"I understand that should it backfire when running on LPG it can destroy the air filtration rubber and plastic pipework in an instant, what can be done to eliminate this risk. "

Fit a flame arrestor. (remember the Davey miner's lamp from your school lessons?)

Something like a tea strainer filter is what's required.

Mike

[docchevron]

You will need to set the ignition timing a bit later (closer to TDC) to avoid backfiring. IIRC it should be reset to some 4deg from 8deg BTDC.

LPG is a higher octane rating than petrol (about 120 octane to put a figure on it) and hence needs more ADVANCE. In the same way that going from 98 octane fuel to 95 octane fuel needs a smidgen of retard, increasing the octane to 120 means you need a fair chunk of advance.

Either that, or you build the engine with higher compression ratio to allow higher efficiency with the higher octane rating, and reset the ignition to suit the new engine.

Retarding the ignition will simply mean the engine will be running at rubbish efficiency.