setting ignition timing for gas

[boggy2006]

hi,

I understand the ignition can be advanced for running on gas, is there anything specific it should be set to and is it just done by rotating the distributer(which way?). (4.2 petrol/gas efi).

Thanks

[Bob]

I think the Valve clearances need to be adjusted also. From memory there is a ex LPG Gas Fitter on the Forum who should be able to help you.

[YNOT]

Timing needs to be set with a timing light. For running on LPG the timing can be advanced a few degrees ie. if the factory setting for a petrol engine is 10 degrees BTDC then you can probably advance it to 12 or 13 degrees. Take it for a drive after you advance it, if it pings you will need to retard it again. If you don't know what pinging is then you really shouldn't be adjusting it at all, lave it to someone who knows what they are doing or you could damage the engine.
The downside to advancing the timing for LPG is that when you switch back to petrol it most likely will ping.
I wouldn't bother adjusting valve clearances for gas as I've never seen any need for it.

Tony

[the evil twin]

Shouldn't need to do valve clearances unless you get erosion... upper cyl lube helps with that (such as Flashlube)

Advancing the timing helps but the main problem is that the RPM versus advance curve for LPG is different to Petty and you actually need it advanced at low RPM and retarded a couple of degrees from the Petrol curve at higher RPM.

You can just go for a compromise or spend money on piggybacking a second ECU for LPG. Most people opt to advance the timing a couple of degrees and live with it but if you are after the best performance an LPG curve is the way to go

[YNOT]

Another way to go about it would be to fit an ECUtalk device which (among many other useful features) will give you the abillity to electronically adjust the timing from the drivers seat. Check this thread for more info; http://www.nissanpatrol.com.au/forum...hlight=ecutalk

Tony

[Bob]

Another way to go about it would be to fit an ECUtalk device which (among many other useful features) will give you the abillity to electronically adjust the timing from the drivers seat. Check this thread for more info; http://www.nissanpatrol.com.au/forum...hlight=ecutalk

Tony

Yeah Have Ordered one and will let the Forum know how I go

[boggy2006]

thanks for all the info. I usually just run on gas and it's running fairly well, odd idle sometimes, but might check the timing to see if it's already been advanced a bit.

Bob, would be interesting to see how you go on with that. It looked like from the last post in that thread that the timing function didn't work though.