inchman Posted March 18, 2014 Share Posted March 18, 2014 i have a 1997 3.9 disco running on lpg. it was running great on petrol but when i switched over to lpg after 6 or 7 miles it started to develop a missfire, i changed the plugs and cleaned all the electric connections i could see and cleaned the vapouriser, took it for a run and still ok on petrol still missing on gas after a few miles. i decided to changed the cap and rotor. this is were the real problems started, i removed the cap and pulled up the rotor arm but the centre shaft of the distributor pulled up along with it, I had to remove the distributor and reattach the weight spring and put it back it, i think ive the static timing set, no1 on compression rotor arm approaching no1 lead, but no start, i pulled a lead and checked to see it i had a spark, im getting an okish spark but it seems to be very sporradic and not as quick as i thought it would be, has anybody any ideas of what to do next, cheers Gary Quote Link to comment Share on other sites More sharing options...
AndrewHorsfield Posted March 18, 2014 Share Posted March 18, 2014 I spent ages trying to static time my Disco, even got the RAC to help! Eventually worked out I was 180o out With reference to spark strength: Try to avoid resistor type spark plugs, NGK are one of the best. Also need slightly wider gap, up 0.9mm, if I remember right. The timing needs to be more advanced than petrol about 18o on gas and 8o on petrol. Also, you need a good quality distributor cap and rotor arm, even some of the genuine ones are not very good. I got so frustrated when I made my Disco 3.9efi that I switched to Mallory. Have you recently replace/uprated the plug leads. Magnacor or similar may a big difference, and leads breakdown. Try avoid squeezing the leads into the little plastic clips It is all about strength of spark with LPG, as it is harder to ignite than petrol. www.v8engines.com is always worth a look. Best of luck Andrew Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 18, 2014 Share Posted March 18, 2014 Resistor plugs are recommended anywhere there is an EFI system, so stick with NGK BPR6ES. 18 degrees is a bit much, 12 is much more like it. v8engines.com is aplace where they take your money and burn it for you, honestly there's very few people on here that have anything good to say about them. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 18, 2014 Share Posted March 18, 2014 Sounds like ignition amp, they are prone to failing and when they're on their way they work when cold but break down when warmed up. Not too spendy to replace, or you can fit a GM HEI one. Quote Link to comment Share on other sites More sharing options...
inchman Posted March 24, 2014 Author Share Posted March 24, 2014 hi all, i changed the ing amplifier and tried it, no start. changed the rotor arm. ( red no rivit) no start. put on new cap and new leads, checked the timing and no start, any body any clues, it getting fuel ( plugs wet ) and sparking arrrghhh cheers Gary Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 24, 2014 Share Posted March 24, 2014 If plugs are wet ther are probably drowned stick them in the oven at 100Cfor 10mins to dry out and refit whilst hot and then try. Quote Link to comment Share on other sites More sharing options...
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