G'day unfamilia. This lpg setup has been done before. In 1994 by myself and it may prove to be an engine melting nightmare. I will let you know where I went wrong with the setup and what I had to do in the rnd to fix it and make it run like a champion.

The first thing is that a 'simple' lpg mixer is a venturi type mixer. The smallest part of the mixer needs to be approx 25% smaller in diamater than your throttle body butterfly's to provide enough neg pressure to effectively draw against the convertor. I used amos mixers from a rover 175cd stromberg and they were almost the same size as the su throat and it caused lean mixtures. It ran smooth and revved but it leaned the L18 to the point of melting the bronze valve seats fitted as standard. New head fitted same problem with the 4gas annalizer.

Second problem is that when you use the plungers of the su you are effectively robbing the lpg mixer of its response from the throttle plate thus weakening the vacum signal to the lpg mixer. The lpg has to not only get past the mixer but the loaded plunger designed solely for the purpose of wet fuel delivery. It is why the su is a 'constant depression' setup. If the mixer size is right and you have enough restriction in the mixer to effectively feed the engine it would be of benifit to remove the plungers so there is only one venturi.

The most effective way to run a twin mixer setup is to use 2 constant depression lpg mixers. 2 impco 125 mixers.

I genuinely hope you have no trouble with yours as your mixers look different to the ones I used but they were designed for a 175 throttle body and not a 150 like yours.

If it does cause problems then I have a spare lpg manifold I made suited to a worked motor for straight lpg. 'VL throttle body and mods to suit either simple or complex mixer' Feel free to give me a pm or call. I am AAFRB accredited and have played with many types of systems although I am far from an expert.

Hope it works well. Don 0418253351