tuning help on v8 coversion

[bentley]

I have a 1989 bentley mulsanne s with a brc conversion,i think. I know nothing about how to adjust it. although i,ve been told it,s a combination of 2 systems(the only thing that would work on this car)and can only be tuned by ear not on a machine. are there any enthusiasts in the london area that can show me how to do this. Since i don,t know the lingo i,m lost reading "how to"online. If you can help my phone is 07957548086 thank you in advance, Lee

[LPGC]

Could ask you what parts are fitted etc but might be better if you could post some pics of the installation (under bonnet LPG components).

This thread details how to post pics on this forum http://www.lpgforum.co.uk/viewtopic.php?f=33&t=12009

And then - why do you think it needs tuning... problem?

My Scouser mate owns a Bentley and a Roller, both models around the same year as yours, one converted with a Prins sequential LPG system, the other converted with either a BRC or OMVL LPG mixer system (I forget which). I've tuned both vehicles for him in the past, I believe he was selling one or both...

Simon

[camaro]

My Scouser mate owns a Bentley and a Roller

Both stolen, I assume?

[LPGC]

Both stolen, I assume?

Hey Hey Hey! Nah, he runs a secondhand motorhome sales firm.

[bentley]

thanks for reply.I will apologise in advance about my lack of tech know how.But will try and find some kid who can do pictures. The reason for possible tuning is the lpg failure to operate at low speeds .ie stalling at stops,going around corners,and generally town driving. When started(easily)after stalling pulls away smoothly but stalls when slowing down. It switches over smoothly between gas and lpg at speed,and travels fine on lpg at speed.I've had mechanics look at it and adjust screws on top and side so it idles properly but within a short time problems return. I believe its the BRC combination system I have.Thanks OAP Bentley guy.

[LPGC]

I'm afraid the lack of replies will be due to the lack of info you've provided, pics really would be of benefit here, 'BRC combination system' doesn't help us know what components you have. Probably not the best idea to have general mechanics adjust settings unless they're familiar with setting up LPG systems.

Having said that, it is possible your cutting out on deceleration could be due to 'ram air'... In the case your BRC system is a mixer type system (and we don't know that yet) - Mixer systems work like an LPG carburettor, air flowing through the 'mixer' creates a vacuum signal to the reducer, the vacuum sucks the gas out of the reducer and this gas goes into the engine along with the air. Ram air is the effect of a forward facing air intake pressurising the air as it flows through the mixer, air under pressure is the opposite to a vacuum hence no vacuum hence no gas (or at least not enough gas) is sucked into the engine. Under engine load the system may run OK as adjustments to settings can allow for the slightly more pressurised air but on engine overrun and when returning to engine idle (when LPG flow would be at it's lowest) the ram air effect can prevent enough gas flowing into the engine regardless of settings.

Simon

[bentley]

simon, thanks for the reply. at least now I understand the theory .As I said I will try to find someone to do and send pictures. I don't own a computer but have access at the library so it may take awhile. Might you know anyone in the London area I could contact that would look at car? Thanks once again for helping an old boy out with good info. and when its sorted and I'm on my way to Scotland i'll call in buy you a drink. Lee

[bentley]

the info I have on equip. 8.5 litre capacity , lpg toridal, omvl R90 tandem, BRC . there is a slotted pin on top which can be turned by fingers and one on the front side to adjust with screwdriver.When I've tried turning them there is no appreciable engine tone difference except it will stall when turned to far. There are no guide marks on the finger tight screw and is now set at a few turns from full tight without stalling. Once again I apologise for lack of tech knowledge. thanks

[LPGC]

Pics of the parts would be of help here, need to make sure you actually have an R90 reducer, could also show us pics of the other parts. You were going to email me some pics? I could post your emailed pics on forum so others could join in the thread.

Simon

[Brian_H]

Pics of the parts would be of help here, need to make sure you actually have an R90 reducer, could also show us pics of the other parts. You were going to email me some pics? I could post your emailed pics on forum so others could join in the thread.

Simon

I suspect the tandem part might actually mean theres a pair of them? As you say photos would help alot here, probably helpful to have photos of anything that can be found to be part of the front end (Reducer(s), any wiring/ECU if there is one, and where the gas gets into the intake for starters, nothing much to gain from anything at the tank end.

You say London - whereabouts actually are you in London?

[bentley]

no it wasn't me that sent spurious email. I'm still working on how to send pics. I'm in hammersmith&fulham area. thanks for replys lee

[LPGC]

Lee (Bentley man) emailed me pics today.

Here they are...





Not the best angles in the pics but I reckon Impco system....

Simon

[Gilbertd]

Is it Impco or a Blos carb? Mind you, I can't even see a vaporiser, it looks like that is tucked away down in the front somewhere.

[LPGC]

Could be Gilbert. I assumed the reducer was the thing you can just about make out mounted front offside in the top pic, in the bottom pic the pipes to the mixer seem to run towards that. Some of the Impco mixers (with various adaptors) look similar to Blos and some Impco reducers look similar to the thing, well, from what we can make out from the bit of the thing we can see.

Edit - just had another look and it does look like a Blos mixer but reducer (if that's what thingy is) probably not an R90.

If this was converted in the UK then it's likely TinleyTech supplied the parts for this conversion and would be able to advise. I've fitted a few Impco systems but Impco has a wide range of adaptors etc that they will be far more familiar with, or will be able to help even if it were something like a Blos setup.

I just receieved an email from Tinleytech on another subject, replied with an email that should draw their attention to this thread.

Simon

[Tinleytech]

That is a Blos mixer but fitted upside down, they recommend to fit with the gas input on top, can be angled either side but must be higher than horizontal. Not certain if this has direct effect on running (or is more for longevity by allowing release of contaminants) but definitely worth spinning it over first.
Adjustment is all on the mixer the small screw in the (what should be) bottom is the idle and the bigger one the main adjuster. Normally set the reducer with the smaller screw about half a turn out from lightly seated and the big screw about 3 turns out from lightly seated. The blos tends to slam the reducer fully open as soon as you get off idle (the slide in the mixer regulates gas flow) so no point in fiddling with the main adjuster on the reducer after initial setting.
Best to check CO pecentage if you can, about 1.5% on idle and 0.75% at 3000rpm is correct but not an exact science!

hope this helps.

[Tinleytech]

Also, these mechanical injection engines really need a 'Stop KJ' emulator box to switch off petrol, if a relay is used instead, slugs of petrol can get sucked through and cause slow speed stalling.

[LPGC]

Nice one! And credit where it is due.
What's your take on the model of reducer then?

Simon

[classicswede]

I was recently advising an installer about the need for a K stop

[LPGC]

I was recently advising an installer about the need for a K stop

That will have been me regards the old classic Merc I saw a few months back? The guy had had one system fitted by a firm but that system had issues, so he went to another firm who removed that system and fitted another system but this system also had issues. Reckoned he'd spent about £10k on just having the head gasket done and having two LPG systems fitted, neither of which worked properly. He approached me on the basis of having me write a report for a court on it which he presumed might heavily criticise both installers, and also to have me sort out the issues with it... But he seemed to go off the idea when I told him I couldn't comment about the first conversion much at all, while the second conversion seemed to have appropriate components fitted and the car had run OK in my presence after I'd made just a couple of minor adjustments to settings and there might not be much scope for further improvements... Then he told me he was off to see yet another installer whom he had faith in because this installer had once converted a VW campervan for him which ran OK. This installer is very close to where he lives, begging the question why, when he had faith in the nearby installer, he didn't go there before coming the considerable distance to me. I did advise him that successful conversion of a VW camper wouldn't have much bearing on whether or not they could improve on results with the the old Merc.

Since we're talking KJet I cannot resist the chance of bringing up the subject of flap openers! 'Hello Mr LPGman could you advise me?'. 'Yes love ooh Kjet petrol system eh. You need a flap opener and you've come to the right place'

Simon

[classicswede]

Vacuum or pressure operated?