LPG, Bio Diesel, Hydrogen, Fuel Cell Questions and Answers last answered over 2 years ago.
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Use good quality leads.. ie known brand.. bosch hella etc...
Plugs... I have only ever used the std plugs in any of mine on LPG and gapped to std setting... if the ign components are in good nick and the LPG is set up nice you shouldnt have a problem really.. you may find advancing the timing a few degrees helps, but you need to speak to someone that can advise about the Aircooled.. (I did run a 1.7L type 4 in the back of an old T25 I had on LPG.. and set it advanced over stock, 5 degrees extra IIRC.. ran real well.. didnt have a petrol system on it at all... cant advise well enough on the CU with twin vac distributor..