Jeep Grand Wagoneer - Single Point System Advice

[Gilbertd]

Don't adjust too much. On the vapouriser, give it no more than a quarter turn at a time.

[Brynjaminjones]

Good morning all,

I'm going to have a play with this shortly, but I just had a thought before I start.

Can I adjust the LPG system with a vacuum gauge like I would when tuning the petrol carb?

[Gilbertd]

Probably not......

[Brynjaminjones]

Right, I've had a good tinker with it today!

I opened the intake flap to the cool air position then tried to tune it first.
Even after getting it to idle as high as possible by adjusting the bias on the R90E, I could get another ~150rpm immediately just by putting my hand over the air intake.

I therefore put the flap back to the hot air position and tuned it like that.

Afterwards the idle improved slightly. It's definitely idling a little smoother. More importantly, I found that I needed to wind the power valves out a little.
Once I was happy I'd got it as good as I could, I put my hand slightly over the hot air intake and the revs immediately dropped, so it looks like it doesn't want restricting further.

I've just been for a good drive and I'm pleased to report that it's more powerful than it's ever been on LPG!

In all the time I've had it, nobody has ever really spent any time tuning it correctly.
I'm sure it's not perfect, but it's much better than before!


Thank you all for your help, I couldn't be more pleased with the results.

[Gilbertd]

Well done, and you've learnt a lot in the process.

[LPGC]

A balancing gauge for multiple carbs wouldn't be of much use but a gauge of manifold vacuum can be useful for getting idle mixture the same as it is on petrol, especially if the engine has automatic idle speed control (or combined with an accurate rev counter if the engine doesn't have automatic idle speed control).

Out of interest, how did idle speed on LPG compare to idle speed on petrol before adjustment and how do they compare now?

[Brynjaminjones]

Yeah, a manifold vacuum gauge is what I used. I did find it helpful actually. I mostly went by the engine rpm, but I managed to fine tune it even further by getting it to peak manifold vacuum.

I didn't actually compare idle speed on petrol/LPG as it's a bit of a pain to switch over. Next time I do though I'll report back!

[CNG]

Unless you've vacuum leaks.... sounds like a mirror the issue i had running 2 x BLOS mixers with an OMVL before it'd run near to Stoich. See my thread on this. To this day I have 1 x cooker-ring + 1 x BLOS on there. Another 'old-skool' and pretty juicy engine with not enough draw on the OMVL.

viewtopic.php?f=33&t=15479&start=20

You likely need a Leonardo, and perhaps 2 x mixers liek me. Leonardo put on hold for now, my BLOS is very, very good so no hurry.