Bentley.

[Gremlin]

Mine was set up like that when I got it and it made a bloody horrible screeching noise..
Its now set with bleed screw out about ? and the main one is **?

I have just been fiddling to get it running and tickover OK.
My Mercedes 500 with same vapouriser wouldnt run properly with bleed screw all the way in.
Mercedes starts on the button, cold hot warm.... Couldnt ask for better and does 15 town and 20 on a run.
Bentley did start this morning on gas and continued to run but I turned it onto petrol to warm up. Half mile and then I turned petrol off and then onto gas. Drove for a few hundred yards and stopped at shops. 10 mins later it started first click on gas.

[Gremlin]

Temperature gauge on car says its about 2 degrees this morning and car started on gas but lumpy. I think its because of the choke still being partially closed.... Think I will knock the choke back a bit further bit by bit and see if it gets better and that it will also start OK on petrol without so much choke.....
Tickover is best adjusted by putting the car in drive, adjusting the mixture, then into neutral, giving it a few blips to settle it down, and then back into drive to see if its better or worse...
The beauty of the Mercedes V8 is that it has a tickover control so even when you pull a plug lead off it still stays at the same revs,(well, within 20 or so) and also when you put it into drive.

[Gremlin]

Have a question about the fuel switch on my car.

Its a Landi C97-C.
Is there a particular way of using this switch when going from gas to petrol so that the engine doesnt stop and I have to crank it over to get it running on petrol?

[rossko]

I do not know about this switch, but most carb style switches are smart enough that the centre position acts differently depending which way you are going.
Petrol -> centre, both fuels off to allow float emptying.
Gas -> centre, both fuels on to allow float filling whilst still running gas. You wouldn't normally need to linger there for more than a second.

[Gremlin]

Seems as if I was right about the automatic choke being the reason why the car didnt want to start on gas..... It would fire once and that was it.

A very crude simple and very very cheap solution.......

an elastic band......

Feed the band around the choke linkage and loop the other end over the nut on top of the manifold.....the band holds the choke in the open position and engine will then start on gas.
If you want to start on petrol for some reason, just unhook the band from top of manifold..

A continual suppy of bands is available from
thrownawaybypostmen.com

or you could use a small spring....

[Gremlin]

Just as a follow up....

Bentley does not run properly with tickover screw screwed all the way in and mixture controled by main jet. Why design a twin output system and not use it as it was designed to be used.

Since the above post regarding the use of the elastic band to keep the choke open (now upgraded to a cable tie) I have not used any petrol at all.... Starts perfectly on gas.... cant feel anything from the engine when its on tickover and in gear... At one point I did find that it was not as perfectly smooth as it should be on tickover in gear, but ok in neutral, and an LPG man I was talking to suggested it was running too rich on tickover...... turned out to be too weak as the engine needs that bit of extra fuel because it is in gear but not allowed to go because you have your foot on the brake.....

[Sir Henry]

This thread has been dormant for a while. Since then I've heard about the kludge of preventing the choke flap from fully closing and used it on a couple of occasions with varying results. It seems that cold or sometimes even warm starting on gas is always a matter of turning on the ignition and then waiting a few seconds for the inlet trunking to fill with gas before turning the key to the start position. Unfortunately it doesn't always work so I may still have to start on petrol and run until the choke flap starts to open. Just as a personal preference I don't like using rubber bands or wire ties in such an application (although I had to when I mislaid a securing collar while replacing the high pressure hose on the power steering).

In the meantime I've located a couple of sources for a closed loop upgrade for the current open loop system. There's a couple from Tinley Tech which include everything for a DIY fit or for your tame mechanic to fit for you.

The second is off eBay which appears to be a Polish design and manufacture and doesn't include either the lamda sensor or the fitting boss to weld into your exhaust. I wouldn't worry about the provenance as a lot of people went over to Poland in the early days of LPG fitting and came back with very decent systems. They don't any longer as prices have tumbled in Blighty in recent years.

The only problem I envisge with either system when trying to use it on an 80's RR/B is that the car may have a twin exhaust system and the way the carbs are set (each one feeding 2 cylinders on opposite banks) up can make measuring the O2 in the exhaust gasses problematical. It depends on which of the several exhaust sytems are fitted to your car and where the first balance tube is located. If there's one in front of the gearbox it may work OK, but that may be less likely if the only one is much further along the system. In either eventuality it would be best to get a 4-wire lamda which has it's own (ignition controlled0 heater built in.

I'll be getting the ebay one soon and attempting to fit it shortly thereafter - except for the lambda boss which I'll have done by one of the very few mechanics I will allow near the oily bits of The Old Girl. Fortunately I have 2 other cars to fall back on if I run into any problems along the way. In any event I shall report back with progress reports as I go.

[Gremlin]

matter of turning on the ignition and then waiting a few seconds for the inlet trunking to fill with gas before turning the key to the start position.

inlet filling with gas with the ignition on but engine not running?

[Gremlin]

Choke.

I bet there are a lot of people on here that do not know what a choke is, as nearly everything today is injection and automatic.

If the choke on an S.U. or similar type carb is closed then there is NO air going into the carb.. and if your gas supply enters the inlet system before the choke flap then no gas is going in either!!! My Bentley does about 11/12 mpg on gas pottering around and about 16 on a run at steady speed and I dont think I will get any better than that.
Best way to improve fuel consumption is to stop driving off from the lights as if you are driving a Formula 1 car... overtaking when approaching traffic lights when you can see the lights are on red and you have got to stop anyway.......screaming along the slip road when joining a dual carriageway and whizzing over to the outside lane.........and then getting off at the next juntion!!!!!!!! When going down a hill.. ease off the pedal.. dont see if you can red line the rev counter before changing gear....
If I drove my Bentley the way I drive my wife's Micra it would do about half what it does now.
On a long run with my 1986 Mercedes 500Sel (lpg) it works out only slightly more expensive than using the Micra.

[Sir Henry]

matter of turning on the ignition and then waiting a few seconds for the inlet trunking to fill with gas before turning the key to the start position.

inlet filling with gas with the ignition on but engine not running?

Exactly. Don't forget that the inlet trunking can't overfill as the gas system should be set up so that it will only feed gas while the engine is actually running except for a few seconds after switching on the ignition after which it will switch off again until it senses that the engine is turning over.

Strictly speaking the carbs on the original V8 RR engine of the late 60's (6.25 litre) to the present (6.75 litre) don't have chokes as such. Instead Crewe fitted a common 'restrictor flap' in the middle of the engine bay with redundant opening systems. As the main one is warmed by the hot exhaust gasses in the 'B' bank manifold the flap will start to open far earlier than most cars and long before the coolant has warmed to any significant degree.

Ps. A choke should never fully close as petrol will not ignite without some free oxygen to combine with. The RR engine is no different as there's still a small air bleed even when the choke flap is as close to shut as it will go.

[Gremlin]

I will hold my hands up to the fact that my Mercedes is wired into the ignition and should I need the ignition on for some reason, I have to switch the gas off.....Never been able to figure out where to wire it to so that its only on while the engine is actually starting/running.

[Gilbertd]

You buy a switch that is intended for the job. Go to www.wtv-uk.co.uk, click on Spare Parts, then Switches, then pick the one you want. They all incorporate a pulse detector that connects to the negative side of the ignition coil. No pulses and the gas solenoids are automatically switched off.

[Gremlin]

You buy a switch that is intended for the job. Go to www.wtv-uk.co.uk, click on Spare Parts, then Switches, then pick the one you want. They all incorporate a pulse detector that connects to the negative side of the ignition coil. No pulses and the gas solenoids are automatically switched off.

Thankyou but I did already know that much.

Far too time consumming trying to figure out which of the many wires is the negative.

[rossko]

Far too time consumming trying to figure out which of the many wires is the negative.

Gosh, basic safety precautions can be such a fag. Please don't let anyone else ride in your car without it, please avoid going on the road as you're probably uninsured.

[Gremlin]

Far too time consumming trying to figure out which of the many wires is the negative.

Gosh, basic safety precautions can be such a fag. Please don't let anyone else ride in your car without it, please avoid going on the road as you're probably uninsured.

No need to be too concerned
I drive very carefully making sure to avoid all the people talking on cell phones...

oh.. and fiddling with sat navs and switches to see how many MPG they are getting.

[Sir Henry]

What he means is that there is a clause in virtually all insurance agreements that the car be maintained to a safe degree and compliant with the 'Construction And Use Regulations' two thousand and whatever. Any car fitted with an LPG system that feeds gas from the main tank while the engine isn't actually running is well outside all these regs and can be considered to be not within the insurance rules. Crash it or hit someone and even if it wasn't relevent to the incident an insurance assessor may find that you've 'lied' on your insurance application and can thereby rescind the insurance. Ipso facto: you were uninsured at that time!

A case in point: My idiot nephew put his occupation as 'welder' on his insurance application as he was a pro-tem welder at the time with an option to take full training as such (which the comapany decided not to follow up on). Unfortunately when he crashed his car into another (the second time in 3 months) the insurance company contacted his employers who said that he was employed as a 'warehouse operative'. He was considered to be uninsured at the time of the ... incident ... and is currently being sued in the Magistrate's Court for all the damages, costs and 'injuries' he caused.