Camshaft?

[tack43]

My 3.9 seems very sluggish/down on power. Seems ok once up to speed & cruises well on petrol. Will idle & rev on LPG but on changing up to 2nd gear it gets a lot more sluggish than on petrol to the extent its undrivable. Could this be a worn camshaft? what other signs should I look for? Or other faults!  :?

[Range Rover Blues]

If it runs on petrol then chances are the cam shaft is ok.  Early signs of cam wear include high fuel consumption and noise.

Probably a bit lean on LPG, that's all.  LPG is harder to ignite, it has an octane rating of around 115, plus it has a lower calorific value so you will loose power.  Some of it can be recouped by advancing the timing, but be careful if you run on petrol as this makes it harder to start and more likley to do damage in the long term.

I use an ignition advance processor on Blue.  The LSE has a multi-point system and these don't seem to suffer any power loss on LPG but it helps bening an auto too. Blue is manual and I notice a drop in torque when towing/fitting big tyres.

[tack43]

So why is it so sluggish? It's had a recent service/emmissions test. My 90 is quicker 0-60! 

[Range Rover Blues]

Check your timing and that the dizzy is working properly.  Is it misfiring under load? denser air/ful mixes are harder to ignite.

Di you close up the plug gaps?

[Rossko]

Could be worn cam ; the effect of low valve lifts is to effectively reduce capacity  and compression ratio of the cylinders - less air throughput.    It would show up more on LPG because that would rather have a higher CR than petrol to begin with, reduced compression will affect it more.

cheers, Ross K