What pressure should a Single point vapouriser/reducer be set to?

[LPGC]

For testing purposes just cobble up some sort of restriction to place in front of the mixer / intake. If venturi size / lack of signal is the problem a big enough restriction will reveal it. Could just use your hand... but it can sting a bit like getting a slap if you get a backfire during the process Use something that won't break up and get sucked into the engine in worst case scenario, metal biscuit tin lid etc. We're only talking moving it over the inlet so it blocks some of the venturi off, you don't have to make holes in anything for this... But I've driven hundreds of miles using a mixer made from a baked beans can! Worked very well.

[CNG]

Will do, already used a combination of a bean-tin and bubble-wrap to do the smoke test. Use of available resources Sarge...

[CNG]

OK, I've had a play and as suggestions...:

a) Try running with SU piston removed

Thought about doing this first, but even if it works, I'm not sure it gets me anywhere or tell me much - I need the piston in place, whereas...

b) 1 x BLOS - choking off inlet
Baked-bean tin.... this helped a lot. It proves what removing the SU piston proves but is quicker to do.

c) Filter >> 1 x BLOS >> 70mm mixer >> SU >> Manifold

This failed. Would barely run, all the screws I could find would be right in and then I could get it to idle - just. AFR was very rich. Oddly it'd die weak just off idle. I concluded this was caused by screws in 'full in" strangling demand. I gave up

d) Filter >> 70mm mixer >> 1 x BLOS >> SU >> Manifold

This worked brilliantly, a bit of fettling and it's pretty much at stoich throughout the rev range. 2 x BLOS helped, this it liked more - runs better still. Power valve fitted only to the cooker-ring. Screwed almost home, PV permits a float-level of gas, the majority going thru' the BLOS.

It still looks a fright, but I'm down to 1 x BLOS + 1 x cooker ring. It runs better than it did with 2 x BLOS. I conclude a suction issue related to the greater demands of the gas. A BLOS, be it one or two is superior to plain mixers in this set-up. The BLOS keeps 'stoich' really well. Simple mixers don't seem to create the suction required without a baked-bean tin? I've the richest needle in the BLOS I could get. If I 'doctor' this one or get an ever richer needle, I reckon I could be rid of the cooker ring. The hero in this set-up is the BLOS.

An AEB Leonardo next.

[robertXX]

Excellent ,well done.

[LPGC]

I think it's great that it's running well but there will be a simpler neater solution. Mixers can usually be fitted with various sizes of venturi, this isn't to say a Blos or even 2 won't do just as good a job but beware drawing conclusions. If 2 Blos' are no detriment to 1 Blos, then 1000 Blos wouldn't be a detriment to 1 Blos.. But it's intuitive that 1000 Blos would be a detriment and maybe could be more of a detriment to airflow than a smaller venturi on a 70mm mixer.

[CNG]

Thanks for the pat on the back RobXX, however I can't see it's truly warranted quite yet. As my post the solution works in this set-up, more by luck than judgement. It shouldn't require two of any mixer, BLOS or otherwise, and LPGC is absolutely correct, it's not elegant. Just better than it was. It works better than it has any right to?!

2-BLOS+Mixer-03-03-20-01.gif (163.74 KiB) Viewed 7223 times

I'm pretty sure with more fettling, from what I've learnt about this set-up, putting the second BLOS back on, and it'd be better still. But I don't want 2 x BLOS, at some point down the line, that's asking for trouble.

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And jeez. That gauge is rather incongruous stuck there, however it's been damned useful... Wavering on/very near Stoich at around 16.9 -17.3, for a mechanical device I reckon that's v.good. Mixers alone won't work, the BLOS is needed to give vacuum, and nearly manages this on it's own. Bought with a P38 Leonardo kit on eBay, I've got another 70mm mixer on the way. Added to my current 70mm mixer, I'll give it a go. 2 x mixers metered via the Leo might provide vacuum the SU mixer couldn't. I would agree with LPGC, I'm reaching for a false conclusion. Shoving an AEB Leonardo on will suffice for much better metering than any classic Land rover warrants, but something is still amiss.

BTW: If you like to know this stuff.... and I do, seen mounting the intake tube onto the rocker-cover, that's what's called a Munson Ring [No, I didn't know either].

[robertXX]

is your innovate WB re set to have cng readings ?

[CNG]

I had to smile. I hope so, we're in deep doo-doo if it's not. I'm not sure it'd even run on 14.7. It so happens I now have the gauge displaying Lambda. Lambda 1.0 is Lambda 1.0 is Lambda 1.0 no matter what the fuel type, and in the odd moment I run petrol, it means the scale stays put. The sensor is reading the O2 left after combustion, thus for Lambda 1.0 that's the same regardless of fuel. Minded to this, I'm not sure what the fascination is with AFR, Lambda is far less confusing eg: you wouldn't have needed the question.

AFR vs Lambda Table1.png (153.06 KiB) Viewed 7208 times

Methinks, at 6.4 for Lambda, methanol might be entertaining. One thing I've looked-up and not found a proper answer to, is why if stoich is perfect combustion, will racers run 'rich'. It gives more power, but why? I had it we want air and as much as the fuel will burn, not less?

[robertXX]

just checking

[CNG]

I remember now, what the issue is, running methanol I mean....

Methanol Drag Racer Fire suit.jpg (84.92 KiB) Viewed 7200 times

"No thank you, I’ll just stand at the bar. I shouldn’t wish to attract any attention." [Adam West].

[DodgeRover1]

why if stoich is perfect combustion, will racers run 'rich'. It gives more power, but why? I had it we want air and as much as the fuel will burn, not less?

From a motorcycle racing point of view is is better (especially with 2 strokes) to run slightly rich than a fraction lean as rich engines don't seize up, running a slightly rich mixture also helps with cooling - less of an issue in these days of water cooling but when everything was air cooled it was.

Probably teaching you to suck eggs but you have wound the transport screws (that there isn't a single damn mention of in the instructions) fully out on the BLOS's?
Are your units ok at the point where the gas hose goes in? Mine has developed an air leak and required a good amount of grease round it to get it sealed.
Mine also has the problem of too much suck - I'll try a weak needle at some point.

[CNG]

Yes I'd read about cooling, yet i've not found a definitive answer to that question. I think I said Tinley Tech were sending me all sorts of weaker needles for BLOS, two apparently identical 'weak' needles found me with one as rich as I've seen. But they were good about this and got it sorted.

[CNG]

Well, save the COVID lock-down thing, I've done a heap of miles lately and it works. 1 X BLOS + 1 x 70mm mixer, and it sits at Stoich for 95% of the time anyway. The BLOS is very good. I still wonder why I need better, but I'm going for a Leonardo on there anyway.

[DodgeRover1]

Looking forward to the updates

[CNG]

The wiring loom is a real mess, and i've been reluctant to add still more complication, until it's sorted. I'm doing a tidy-up before I hang the Leonardo on.

[DodgeRover1]

Following your tip here I added a power valve before my BLOS, it running a lot closer to stochiometric when reving now without needing the main mixture adjustment on the BLOS to be virtually closed off, I just need to sort out my A/F ratio meter as its had a hissy fit - i think due to the lambda getting clagged with oil from the worn engine, If i really hammer it and let it rev out it will work for a while before failing to read again

[CNG]

Interesting to hear you've found my solution works for you too? Odd, I'm still not convinced I understand why it is necessary in my case, yet it works for me?
Progress on this aspect of my project has come to a halt. It works well as it is.

[CNG]

Yes it works, but why?
It's been a while now, and I've still not got round to improving on this. My current pet-theory for why it needs a BLOS and a power-valve, (or at one point 2 x BLOS), is that that there's already a variable-venturi device sitting upstream. The SU carb? Lest we forget... a BLOS operates much as a an SU.

Thinking about it, if we were to daisy-chain 2 x SU carbs would that work?
If we install: Filter>> No.1 SU >> No.2 SU >> Intake manifold...
If for some mad reason, we did do this, the variable venturi operation of No.2 SU sets to choke the vacuum thru' No.1 SU, preventing correct metering for the No.1 SU. Effectively that's what we have here - The BLOS can't meter as it should because the air its gets is less than it expects. Or am I taking 2+2 and getting 5?

I'm still not convinced the current pet-theory makes rational sense.
If we did have two daisy-chain SU carbs all No.2 SU would do is speed-up the air thru' it, which should NOT affect the 'actual' volume of air thru' the No.1 SU? Thus 2 x SU should work, excepting of course to run at stoich each would be required to supply differing proportions of fuel. No.1 SU carb would give greater vacuum to No.2 SU. I think the key is here somewhere.

I like to have a proper explanation for why this 'abortion' works, as I said " It works better than it has any right to?!" so I won't mess with it, but methinks, my logic and explanation remains woolly somewhere.

OK, some of TinleyTech's rich BLOS needles didn't work, but an extra BLOS or (as now) a power-valve did... that's madness? I like to know this stuff.

Still perplexed. Yes it works, but why?

[CNG]

Covered in another thread on this forum, I'm working on a Volvo conversion. I'll get back to the final leg of this job at some point, only I'm very happy with what I have. As I said, this 'abortion' works and works well, it starts from cold on gas, and in all weathers.

This is not one of those tragic beard-brigade classics that only sees August roads. This is used as a year-round daily-driver, and I love it. I can't remember when I last ran liquid. I own mine to drive it, I'm afraid I'll never grasp why you'd own a classic and not drive it? This thing's out in February too. This is a real-world success, and this conversion makes daily-use possible, and affordable.

What more could I want?