What kind of static advance are you running? If the timing is set up for petrol, and the dizzy is on a petrol curve then this could be a major contributor. You should keep the plug and breaker point gap the same as for petrol as changing them will not give you a better spark. There are probably two things going on:
1)Your initial timing is not advanced enough for gas
2) Yours points dizzy is not providing the fat spark that gas needs.

Youll probably need a HEI dizzy graphed for gas to make the 186 work.

Anthony.

a good sparky can regraph dizzy....
on gas you need good spark
get new plugs,,dizzy cap,,leads etc.....good coil

.....did also read to close plug gap by 5 Thou less than recommended and go 1 range colder .......

thats what i did as well.......

what mixer did you get..(gas carby)

i went vk efi manifold with throttle body....

made a huge difference

if you advance dizzy to much petrol wont run..

quote:

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Originally posted by Anthony333
My static advance is on 10 Degrees Btdc... i have been looking on the net and i see about 26 degrees static... ? Is this correct ? I know LPG needs to be ignited earlier, but that seems quite a lot earlier ....

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That is pretty far out. Maybe all up total advance at 3000 rpm should be 26 degrees, but initial on gas can be between 12 and 18 degrees usually. Depends on what kind of curve your dizzy has. I think gas is steeper and levels off earlier. Its a bit of a compromise if youre running dual fuel though, if you go too far it might not run on petrol.

Maybe try advancing the timing to 16 degrees or so and if that makes a big difference then you can decide from there. Before you go getting your points dizzy regraphed maybe another option would be to run an electronic ignition with a module with multiple curves so you can have one for petrol and one for gas. Thats pretty expensive though.

Im running 16 degrees initial with 30 total at 3000 rpm and that runs just fine on both LPG and petrol, but then again this is a 308 on premium so not exactly the same thing.