hi guys looking at a classic running 0n lpg is there any common problems with the v8 lump?
im told i should see 250 miles from £30?
so any advise on owning a classic common faults and anything else will be great cheers

hi mate , i would say thats maybe about right for a properly set up lpg powered classic , depends as always on your driving style .
although i now run a p38 ive run a few classics and i love em , much more simple to work on than the p38 .
my advice if your new to the marque is take along someone who is clued up on them , if thats not possible then bear in mind these 3 words , corrosion, corrosion, corrosion !!!!!!!! main areas to check are:~
1 rear body xmember ( the one above the chassis xmember ).

2 the sills both inner and outer .

3 inner wings .

4 door pillar bottoms .

ive owned a couple of very late classics ( m reg and n reg ) and although they were perfect bodily both had rear body xmember issues .
whilst its not a difficult job to do it is very time consuming if you are to do a proper job , and tbh forget patching it , just fit a new one .
a nice well looked after classic will serve you very well , but a bad one will put you off for life , i hope this helps .
rick.

That's 19 mpg

I currently get 11mpg at a steady 70mph, but it might be because I'm running on an old single point system or maybe running too rich and need to have it checked out.

Somebody on here suggested that 14-15 mpg on lpg was more realistic.

Yup, my thoughts entirely. Got a 3.9 on LPG, getting around 14mpg on a long run. Got some tweaking to do which should bring it upto around 18mpg.

Also got a Classic on LPG single point and i reckon i get 11 mpg. When you say do some tweaking............what are you going to do if i may ask. I know my system has an adjusting screw on the vaporiser and one on the air pipe that goes into the plenum chamber.
Are these the things that need to be tweaked???

System is running correct as per Chris's instructions from RPi. Going to purchase the improved ignition amplifier which gives an extra 10-14 degrees of ignition advance when on gas and ups the spark voltage to about 50kV from about 35kV as standard.

Already got K&N filter, tubular headers and stainless sports exhaust. If I win the lottery I might get the Optimax dual fuel ECU for another £350...

Ahh right, Understand about the filter but that's about it. Bit too techy for me,I'll just be sticking to 11mpg by the look of it. Although someone did mention if i get a straight through pipe and do away with the middle silencer i might save on fuel???

Yup, but you need to adjust the engine settings to make full use of the modifications. That's where it starts getting a bit expensive, well same price as a service from a main stealer...

My local LPG chap hates the likes of K&N filters for some reason.

I've had a few Classics with LPG, 15mpg on a run should be easily within reach for anything that's set up right using standard parts, never mind using special tweaked stuff.

I'll be a bit ****ed off if my turbo one doesn't do 15 mpg on gas when I get it converted.

As a complete novice to this LPG stuff, could someone give me list of simple things that might increase the mpg without changing the whole system to a multi point system.

Would a K&N filter help?

I don't want to change exhaust,

I'm going to get the LPG system checked by the people who installed it some years ago (luckily the Classic hasn't moved far in the last 8 years) to make sure the mixture is correct.

What does this dual fuel ECU do, is it worth the money? Obviously it's cheaper to change that than the whole system?

Any other ideas as 11 mpg isn't great.

Thanks

ECU and fuelling info page:
RPi Engineering - V8 Engines

Ignition pages:
RPi Engineering - V8 Engine - Electrical

LPG specific info is listed there as well. RPi did the LPG conversion on my Rangie, but a few years back now and is due an update.

Dr W said:

As a complete novice to this LPG stuff, could someone give me list of simple things that might increase the mpg without changing the whole system to a multi point system.

Would a K&N filter help?

Click to expand...

A decent set up is probably all that's needed.

K&N filter probably won't, well, it'll help when on petrol, but AFAIK they don't help much on gas. Doesn't make sense to me..

Get it on an emissions tester, tweak it until the lambda reading is around 1.01 and 1% CO at idle. The screw on the vaporiser does the base setting, the one on the pipe going to the inlet manifold does the vacuum side of it. Quite often there's a mark on the one on the vac pipe and a corresponding mark on the pipe itself. Turn it in until the engine starts to run badly, then back out a turn, maybe two. If your Rangie is auto, put the transfer box into neutral, the handbrake on, and the main gearbox in drive - that way the oil pump in the gearbox is working and you won't overheat the gearbox when you rev the engine. You'll need to clear the engines throat out every couple of minutes by removing the emissions test pipe from the exhaust and revving the motor to 2000 rpm or so for 15-20 seconds. Check the mixture doesn't lean off too much at 2500 or so, try and balance out the settings so the lambda reading at 2500 is 1.00 or 0.99ish. It's better to have the motor running slightly rich at 2500 than going lean.

Also make sure your plug gaps are right, if the gap is meant to be 0.9, set them to 0.8 as that seems to work well with LPG.

Take it for a spin, if it's backfiring or hesitating, you've probably set it a little bit too lean, wind the screw on the vac pipe out 1/4 of a turn at a time until it drives like it should then check the emissions again.

This is all I've done in the past, and it's worked for me. It's not a definative guide, and probably quite a few on here will know more than me about it and correct me where I'm wrong.

Thanks for the info guys.

I'm going to get the mixture checked out and then see if there are other options to improve things further.

Cheers

Drw