Classic cars forum & vehicle restoration.

[XL391]

Afternoon Ladies and Gents,

I am the owner of this thing and I have a problem, I think, with the fuel system and I was just wondering if I could pick some brains?

I run a twin choke Nikki carb on this engine, the 1600cc SOHC unit. The symptoms of the problem I have are:

1. Slight initial misfire when revved after idling
2. Sometimes on large or sudden throttle openings, engine feels like it gets starved of fuel causing car to 'kangaroo'
3. After driving for a while and stopping, car will idle normally. When you press the accelerator to move off, the engine will begin to gradually cut out, similar to when a car runs out of fuel, unless you quickly pump the accelerator. If it does cut out, the car will restart pretty much straight away.

I suspect an air leak somewhere? What do you guys think? Your opinions/answers are appreciated!
_________________
Regards,

Will

1972 Daimler Sovereign 4.2 Series 1
1965 Sunbeam Tiger Mk1
1968 Triumph 1300

[PAUL BEAUMONT]

Could do with a few more clues, like has it just started this errant behaviour or does it follow the fitting of the carb or something else? I find that most problems relate to something that has recently been done.
That said if it is a suddenly occurred problem and you have checked all of the obvious things, make sure that the brake servo is not leaking. This is an annoying source of an air leak that is sometimnes difficult to notice. If serious enough it will be accompanied by a hiss from the unit.
Good luck!

paul

[Jim.Walker]

I am not familiar with Nicki Carbs, but generally on twin chokes the engine runs on one choke initially so the air speed through the first venturi does not fall too low and cause petrol starvation. The second choke only opens to allow more air through as engine revs rise.
Is it possible the second choke throttle butterfly is opening too early, or is stuck partly open or not closing fully?
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Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!

[XL391]

Gents, thanks very much for your replies, i'll check both of these when I get back home!
_________________
Regards,

Will

1972 Daimler Sovereign 4.2 Series 1
1965 Sunbeam Tiger Mk1
1968 Triumph 1300

[Nic Jarman]

If the butterflies aren't closing properly it would not idle OK. Some carbs of that era had a pump that squirted petrol directly into the inlet to stop the engine stalling on sudden opening. It sounds like this is could be the problem if it is not set correctly of maybe the diaphram is perforated. Good luck
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1936 Morris 8 Series 1
1973 MGB roadster
1977 MG Midget 1500
Dax Rush

[Nic Jarman]

I had a chat with a friend who works for Past Parts in Bury St Edmunds and his advise was to refurbish the original Solex carb and put it back on. They often get problems with the replacement Japanese carbs.
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1936 Morris 8 Series 1
1973 MGB roadster
1977 MG Midget 1500
Dax Rush

[XL391]