what is good tuning procedure for 3.5 carbie / lpg

[JaapRoskam]

I have a Rangie 1982 with 3.5 carbie on dual fuel. Recently had to replace the timing gear and took opportunity to clean and rewire ignition. Now have to retune it all. Got it reasonably going but not perfect.
It has an Italian BRC AT90E LPG converter. On one side a allan key adjustment screw and thumb adjustment. The thumb-adjustment seems to be to most sensitive in adjusting and then we have the big inline screw valve to the carbies.
First Q. What would be the best timing advance to start - it is a standard 3.5 engine, standard Lucas electronic ignition. Then what RPMs to tune the LPG and how ... Any help is soo welcome . Cheers ! jaap

[bee utey]

I have a Rangie 1982 with 3.5 carbie on dual fuel. Recently had to replace the timing gear and took opportunity to clean and rewire ignition. Now have to retune it all. Got it reasonably going but not perfect.
It has an Italian BRC AT90E LPG converter. On one side a allan key adjustment screw and thumb adjustment. The thumb-adjustment seems to be to most sensitive in adjusting and then we have the big inline screw valve to the carbies.
First Q. What would be the best timing advance to start - it is a standard 3.5 engine, standard Lucas electronic ignition. Then what RPMs to tune the LPG and how ... Any help is soo welcome . Cheers ! jaap

Timing 6-8 degrees BTDC at idle

Set knurled knob on converter for best idle.

Set power adjuster in hose (main mixture) for maximum revs when holding the throttle steady at around 2500 rpm. Unscrew until max revs are obtained, screw back in to the point where revs are just about to drop.

Reset idle if needed

Let engine idle, then rev up engine with full throttle a couple of times.

Test power adjuster a bit each way to confirm best power setting.

Test drive

Reset power if needed

[JaapRoskam]

Hi Bee Utey , what to do with that alan-key screw above the knurled 'idle' knob, it seems to affect something as well. Jaap ( you're a GEM for giving such detailed help anyway!!! ) Thanks !!

[bee utey]

What to do with that alan-key screw above the knurled 'idle' knob.

I don't see many of these, not sure how it goes. If unscrewing it adds gas then try first screwing it right in, set the idle on the knurled screw, screw knurled knob back in until the idle is slow, unscrew allen key knob until smooth idle is again achieved. The main reason converters have 2 screw adjustment is to enable smooth transition from idle to medium rpm. Too much gas from one screw or the other leads to either erratic idling levels or a flat spot off idle. Just play with the balance between the 2 screws until it runs smooth at idle and above.