Datsun Bluebird 180B - Nikki carb fault?

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Talking Hoarse
Posts: 76
Joined: Wed Jun 15, 2011 5:46 am
Location: Winchcombe, Glos, UK

Datsun Bluebird 180B - Nikki carb fault?

#1 Post by Talking Hoarse » Wed Jul 25, 2018 4:27 pm

The old Datsun has been misbehaving. It is a 1983 Bluebird 180B, 910 estate so with L18S engine, and a Nikki twin choke downdraught carb.
It was running really well a couple of weeks ago but had started running rough & lumpy after I refilled with fuel, especially between 2000-3000rpm. I have probably used all of that fuel by now but fault persists.
I had initially checked & cleaned the points - all well of course but no improvement.
Then after a further run I found the plugs were sooted & black. But the crank breather is dry (it doesn't use oil). When I peep down the air intake the choke flap is open (ie not restricting air flow) - I have already mostly backed off the auto choke. On a long run at the weekend, I estimate about 15-20mpg that is well out of sorts as well as out of my pay grade, and dropping to 2 or 3 cylinders as if flooded at times. Notwithstanding that it will sit and idle quite happily.
The float level is about midway up the glass peep hole (these carbs have a peep hole in float chamber - this indicates correct float level)
Anyway - took me a morning to get the carb off, and have now dismantled and cleaned and reassembled. It was spotless clean inside, and nothing seemed loose or perished so no fault found. But I am no expert.
However I have tried the car again but it is still running very very rich with a black sooty exhaust, and at least one black sooted (but not wet) spark plug. Seems to still run OK at idle, and moderately on 2nd choke.
I believe the carb is a 1983 NIKKI 21A304-341

Help!!
Who can help me?
Do you know of any carb gurus in or near Gloucestershire?
Thanks in anticipation ….
Ed

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JPB
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Joined: Fri Jan 07, 2011 3:24 pm

Re: Datsun Bluebird 180B - Nikki carb fault?

#2 Post by JPB » Sun Jul 29, 2018 1:13 am

Hi Ed, I'm toiling to find anything on the web about that type of carb, but as many downdraught devices with fixed jets are so similar in their basic way of working, I would tend to go looking for a physical obstruction - possibly a very tiny lump of debris that came with that fill of fuel - in the area where the float needle and its seat come together. I'm assuming that you haven't been able to view the float level under normal driving conditions?

Meanwhile, I shall continue to look for more info on the carb before suggesting that it could be replaced with a suitably jetted Weber 34 ICH or similar if all else fails.
;)
John, Operating knackered old sheds as daily transport since 1981. :|

Talking Hoarse
Posts: 76
Joined: Wed Jun 15, 2011 5:46 am
Location: Winchcombe, Glos, UK

Re: Datsun Bluebird 180B - Nikki carb fault?

#3 Post by Talking Hoarse » Sun Jul 29, 2018 6:34 am

Thanks John
No further progress, excepting I have located & ordered kits from Japan for washers, seals, gaskets etc. Probably take a week or so to arrive.
I am a bit reluctant to strip down the carb and rebuild when the bits come - hoping to find someone (very much) more expert than myself to do this!
Ed

Talking Hoarse
Posts: 76
Joined: Wed Jun 15, 2011 5:46 am
Location: Winchcombe, Glos, UK

Re: Datsun Bluebird 180B - Nikki carb fault?

#4 Post by Talking Hoarse » Thu Aug 23, 2018 5:14 pm

Some time has passed, some work /effort but sadly no progress.
I confirmed that the float needle valve is closing off fuel supply, and that the fuel height within the float chamber is maintained when engine is running. This Nikki carb has a small glass spy hole with a dot to indicate the float level - it was at upper part of the dot, so I lowered level (by bending tab on float) to lower to part of the dot.
I also blew back the return pipe to the tank (my carb has 2 fuel pipes, a fuel feed from pump, and a return for unwanted fuel to tank)
Still runs like cr@p, very rich but will sit and idle OKish.

The service kit(s) I ordered from Japan never came - the order was cancelled as parts no longer available!!
However I am now eagerly awaiting a Meat & Doria service kit from Autodoc.co.uk, for about £30. I have also tracked down a Weber conversion kit, but that seems to clock in at over £300 whioch is well beyond my pay grade for the heap.
What I did trip over, is that this carb seems otherwise described as a Nikki DCH340, and appears to share service kits with some Hitachi carbs, so I wonder if there was link between Nikki & Hitachi.
So - no real progress, and still hunting for a sympathetic carb person within 50 or so miles...…
Ed

Talking Hoarse
Posts: 76
Joined: Wed Jun 15, 2011 5:46 am
Location: Winchcombe, Glos, UK

Re: Datsun Bluebird 180B - Nikki carb fault?

#5 Post by Talking Hoarse » Sat Sep 22, 2018 11:28 am

YIPPEE - SORTED AT LAST!!
I did receive the Meat & Doria service kit from Autodoc (took about a week to arrive from Germany). I was reluctant to open up the carb yet again without expertise or plan, so engaged Central Motors Cheltenham to sort. Recommended to them by an retired /veteran local mechanic. They seem to specialise in air cooled VW's but have all variety of work in, and a tidy organised workshop. Expecting the work to be entrusted to an old timer (ie familiar with 30+ year old carbs) I was delighted it was sorted by young Craig - who enthusiastically dismantled, sonic cleaned and rebuilt.
Bill paid, and all now seems well again at last. Root cause was inconclusive, probably muck and a batch of dodgy supermarket fuel.
The M & D kit was a bit alarming as it referred to a Hitachi carb - although the diagram looked just like my own Nikki - but clearly many of the bits inside fitted correctly.
So the heap is back in action once again (to be on parade as usual at Gaydon and Bourton on Water museums regularly as well as at rallies and Prescott etc), and I can now get on with all the other jobs lined up for it, having got this step forward.
Thanks again for contributions.
Ed

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