sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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LPG on SU carbs?sowen
@sowen
Club Retro Rides Member 24
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Jun 23, 2013 12:21:25 GMT
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I've got a quick question for the RR masses, how does LPG work with carbs when switching over? As far as I can tell, the carbs will still let fuel through until the float chambers empty enough to stop fueling, so how does it work? My parents used to have a Discovery 3.9 V8 on LPG so I've got a good basic understanding of it when running alongside fuel injection.
My circumstances have changed over the past year, and I have a nice carb'd V8 sitting beside my Land Rover and I think I can justify a V8 on LPG now. The other option would be to throw money at the engine and fit injection to start it and when running low on LPG, as I've read somewhere that SU carbs have a tendency to wear the needles when no fuel flows through them, though I believe there is a modification to fix that?
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Jun 23, 2013 18:38:17 GMT
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When you switch over to gas you pause between the 2 settings(both fuels off) until it starts to splutter and then switch to gas, on the reverse lpg -> petrol you just flick straight over, simples once you get used to it - I can do it with an auto without it stalling. Have heard about but never seen any evidence of needle wear with our RR which has been on gas since the late 80's.
The key to a decent conversion is the correct sized mixers (and a good spark), if you just lash on something that will fit yes it might work but chances are you'll never be really happy with it.
You may (or may not) need a non return valve on the petrol return line as well or it will tend to suck through it when running on gas.
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Last Edit: Jun 23, 2013 18:39:45 GMT by dodgerover
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Jun 23, 2013 20:24:51 GMT
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ive never seen a good conversion on a landy v8 running carbs, seen load of really bad ones on EFI lumps as well. However , the systems that inject the gas into each inlet port on the manifold are defo the best from all that i have seen fitted. don't ask me for a name though , as i can barely remember mine!  I have seen these on both carb and EFI lumps and they work loads better than the mixer ones IMHO. |
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'88 Cadillac Brougham hearse (white)
'91 Carlton GSi 24v
'72 Dodge dual cab pick up
'99 Mercedes S55 AMG
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Jun 23, 2013 21:05:20 GMT
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ive never seen a good conversion on a landy v8 running carbs, seen load of really bad ones on EFI lumps as well. However , the systems that inject the gas into each inlet port on the manifold are defo the best from all that I have seen fitted. don't ask me for a name though , as I can barely remember mine! I have seen these on both carb and EFI lumps and they work loads better than the mixer ones IMHO. I'll take some photos of our basic open loop setup, when i get a chance, its spot on, (and get mixer sizes) even our local installer has used the same mixers now for his own RR (+ load of other fancy gadgets) after he had a drive. There really are a lot of bad conversions about, but there's absolutely nothing to be gained from the extra expensive of putting a sequential injection system onto a carb'd V8. You would be better spending the extra money on a megajolt with a decent map to control the sparks. Don't ditch the airbox though - K&N + LPG don't go well together in my experiance, the system relies on a vacuum to work...Also remember if it doesn't go well on petrol then its not going to be better on gas. Tubbs is the man to answer this one professionally though. |
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sowen
Club Retro Rides Member
Posts: 2,245
Club RR Member Number: 24
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LPG on SU carbs?sowen
@sowen
Club Retro Rides Member 24
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Jun 23, 2013 21:38:42 GMT
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I've got Megajolt on my engine already, and the carbs were spot on when fitted to a 3.5. The multi-point/sequential types would be my preferred choice, but it does sound like carbs and LPG aren't the best together.
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I have seen these on both carb and EFI lumps and they work loads better than the mixer ones IMHO.