ChrisLeary
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| posted on 27/1/12 at 09:51 PM |
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Nikki Carb Rejetting
Evening all,
I hope you've all had a good day?
I need to pick the brains of the collective if I can please? My Dad is down visiting and we've been chatting about the fuel consumption of his
Lomax, namely, how high it is...
For reference to the question, the Lomax 3 wheeler uses the Citroen 2CV as the donor, the engine in question has uprated pistons and cylinders,
electronic 1-2-3 igniton and a Nikki Carb.
What I'd like to ask is;
Does anyone know anything about Nikki Carbs, and whether rejetting, or anything else will help towards lower fuel consumption?
Thanks in advance,
Chris (and Dad) 
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BaileyPerformance
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| posted on 27/1/12 at 10:15 PM |
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Hi Chris,
The first thing to do is find out what the fuelling is like at the moment, the best way to do this is to install a wideband sensor such as an LC-1.
If this is not possible simple plug reading can give you some idea of whats going on in the engine, if the plugs are alittle sooty this would indicate
a rich mixture.
Normally an air cooled engine is calibrated as standard to run on the rich side (compared to a water cooled one) to help with cooling, so any carb
alterations must be done with care as a lean mixture will cause the engine to overheat.
A common problem with Nikki carbs is the float level, the float needle valve is prone to wear causing the fuel level to rise or even flood. Some Nikki
carbs had a glass window so its simple to check the fuel level with the engine running.
One final thing to think about, if MPG is poor it mite not be the carb at all, retarded ignition timing or incorrect grade of plugs can really bugger
up economy!
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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ChrisLeary
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| posted on 27/1/12 at 10:30 PM |
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Hi Dale,
Thanks for the reply, I knew someone would have some information on the matter.
The information about the timing was certainly something new and very helpful.
You know what they say..'Everyday's a school day!'
Cheers again,
Chris (it's a long time since school for my Dad! But he says thanks too)
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BaileyPerformance
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| posted on 27/1/12 at 10:39 PM |
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No problem!
Neva played with a 2cv engine, but have fiddled with several Beetle engines (same sort of thing!!), i would guess you need around 28deg of total
timing. To check the total timing rev the engine to 4000rpm and check with a dial-back timing light, should read around 28, let the engine idle and
you should get 5-10deg at 800rpm. I'm sure the actual factory timing settings could be found on the tinternet.
Advancing the timing (no more than 30deg at 4000rpm) will help MPG. Plugs should be grade 6 (NGK) and must be R type (resistor) if you have fitted
electronic ignition.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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rusty nuts
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| posted on 28/1/12 at 11:24 AM |
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The 2CV engine isn't really like a Beetle engine at all , it has no distributor as such and the flywheel has to be removed to get at the points
which may well have closed up . After setting the points the timing for a standard engine is set staticly using a rod of a certain diameter push
through the block into the flywheel as a setting point IIRC . It's been a while since I did one , Sorry if it's a bit vague, it's
like my memory.
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paulf
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| posted on 29/1/12 at 11:34 AM |
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Sounds like a lawnmower engine to me then (' '
Paul
quote:
Originally posted by rusty nuts
The 2CV engine isn't really like a Beetle engine at all , it has no distributor as such and the flywheel has to be removed to get at the points
which may well have closed up . After setting the points the timing for a standard engine is set staticly using a rod of a certain diameter push
through the block into the flywheel as a setting point IIRC . It's been a while since I did one , Sorry if it's a bit vague, it's
like my memory.
[Edited on 29/1/12 by paulf]
[Edited on 29/1/12 by paulf]
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paulf
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| posted on 29/1/12 at 11:38 AM |
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I had a Nikki carb on a hillman imp once that had a glass panel in the float bowl, it was never very successful and I ended up fitting twin strombergs
which were a lot better.
Paul
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