1.0 Carb rebuild kit & Manual Choke?

Hi All

Been living with the Micra now for around 4 months and its been great, up until my mate thought it was a good idea to take the carb off for a clean. I know sod all about carbs and I took his word for it that the gaskets would be OK.

Obviously its never been taken off before, and I spent hours making a set of gaskets which fitted pretty crudely.

I've been searching high & low for a carb rebuild kit to no avail, the winters getting closer and i'm getting more nervous about it not wanting to behave properly.

The automatic choke no longer seems to work, either... have to keep my foot on the gas for a couple of minutes to stop it from stalling so I can only assume the choke is at fault. Are there any manual conversions available for these?

Thanks all
 
OP
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J
Think thats a job for the weekend then, Should have a load of blue Hylomar (I've got a K-series too!)

Any idea with the choke? It would be nice to get that sorted at the same time, unless theres something that might be causing my auto choke to not work, which is repairable?

Cheers Enuo :)
 

h701micra

Deactivated Account
There's no kit or conversion available but they used to be manual. Maybe try and source an older carb with cable etc?

Just an idea :)
Again with the repairing the auto choke its easier to source a second hand complete component
 
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Might be worth doing lol. I'll have a look to see if I can find any being broken.

I didn't know the earlier ones came with a manual choke though, mines an '87 so i thought they all would be :)

Is there something that might be repairable in my current choke? The flap moved freely it just doesnt seem to operate when the car is started.

Cheers guys, very helpful :)
 

Enuo

Glorified Electrician
Auto choke sucks, manual is almost fool proof and can help diagnose lean running when you're tuning the carbs...
 

h701micra

Deactivated Account
You mean these things dont actually work?? :O

I'll see about having a play with it over the weekend... Probably make things worse but ey-oh.

Injection is so much easier :)
Haha nooooo they're a money clinchers thats it. Unless you've a turbo then they can be helpful

Unplug the auto choke relay. If its the same then that's the problem :)

Injection is easier in theory but when a carb works they're just awesome
 
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Haha, I was joking. They wouldn't be any use with a turbo though, surely? I'm in the process of (slowly) building a compound charged rover T16 engine, If i put one of these electric superchargers on all I can see if it being eaten by the engine lol.

I'll give it a go over the weekend, cheers dude :)
 

h701micra

Deactivated Account
Haha, I was joking. They wouldn't be any use with a turbo though, surely? I'm in the process of (slowly) building a compound charged rover T16 engine, If i put one of these electric superchargers on all I can see if it being eaten by the engine lol.

I'll give it a go over the weekend, cheers dude :)
If they're pre turbo they can reduce lag. No point on smaller low boost turbos. I used to have a large turbo and lots of boost. Kept the turbo in positive pressure rather than a vacuum :) saved me twin turbo'ing it

Ooh... you must inform of this turbo build :)

No worries hope it goes well :)
 
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Its only in its early stages at the moment, Looking to go with a T28, undecided on supercharger as of yet but im not going for big power, I want it to be quick but ultimately a brilliant driver, Circa 300bhp in my Rover BRM.

When i get a bit closer to completion i'll see about popping up a thread on there :)
 

h701micra

Deactivated Account
This I'd love some dyno figures for... Skeptical might be putting it lightly... :p
Haven't got any :( this was back on the celica. I have purely logical thinking to share :/

I know that boost is produced by the exhaust gas etc. But a turbo can spool as fast as it like. But the compressor has to physically draw air in. Like our n/a engines. So aiding it by providing it with an already postive flow. It helps. We're not talking 2 seconds reduced lag time. Its more 0.2... but I am that pedantic
 

h701micra

Deactivated Account
Its only in its early stages at the moment, Looking to go with a T28, undecided on supercharger as of yet but im not going for big power, I want it to be quick but ultimately a brilliant driver, Circa 300bhp in my Rover BRM.

When i get a bit closer to completion i'll see about popping up a thread on there :)
Pop a thread up anytime. Love to see progress :)
Forget the name of it but a toyota supercharger is probably your easiest bet :)

300hp in a BRM should be good fun :) I like the way you think... good drive over power :)
 

Enuo

Glorified Electrician
Haven't got any :( this was back on the celica. I have purely logical thinking to share :/

I know that boost is produced by the exhaust gas etc. But a turbo can spool as fast as it like. But the compressor has to physically draw air in. Like our n/a engines. So aiding it by providing it with an already postive flow. It helps. We're not talking 2 seconds reduced lag time. Its more 0.2... but I am that pedantic
The engine draws air faster than the fan can move it except at idle, and fans don't really produce any compression so there is no increased air density so I don't see where the gains could be...
 

h701micra

Deactivated Account
The engine draws air faster than the fan can move it except at idle, and fans don't really produce any compression so there is no increased air density so I don't see where the gains could be...
Not density nor pressure I'm talking about. Purely flow rate.
Those crappy fans no hope... not saying mine is fantastic but its definitely better than your standard ebay job. Cost me £50 to build
They only help at idle as you say, between gears assuming all air 'dumped' and when coasting and boost has dropped off

There's no "gains" purely reduced spool time / effort
In no way do they add power or air pressure
 

Enuo

Glorified Electrician
total possible (edit: volumetric) flow is set tho because its a closed cycle engine, if the fan doesn't generate enough pressure to activate the wastegate or bov then there is no change in flow with or without fan.
 

h701micra

Deactivated Account
total possible flow is set tho because its a closed cycle engine, if the fan doesn't generate enough pressure to activate the wastegate or bov then there is no change in flow with or without fan.
You're thinking into it too much.
It is purely to provide the the turbo with a positive air charge rather than it being in vacuum. That's the difference we're looking at
The fan can produce 1-2 psi at full rpm (24,000)
The turbo spools too quick and takes over from the fan with a matter of a tenth of a second. But without may take 3/4 tenths of a second
Edit: don't forget we're talking a large slow spooling turbo here
 

frank

Club Member
a tubby "pressure" works centrifugally tho surely ? the air is thrown outwards around the edge of the impeller, the intake blades just feed it
very exaggerated by this gas compressor, but same principal

275px-Centrifugal_Compressor_Impeller.jpg
 
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I think the only solution to this is to get your car onto a dyno with and without.

It will show the ever so slight decrease in lag if its the case :)
 

Enuo

Glorified Electrician
a tubby "pressure" works centrifugally tho surely ? the air is thrown outwards around the edge of the impeller, the intake blades just feed it
very exaggerated by this gas compressor, but same principal

View attachment 25795
Also, looking down on that image the impellor rotates anti clockwise, and a positive feed to it will tend to make it run clockwise...
 

frank

Club Member
Also, looking down on that image the impellor rotates anti clockwise, and a positive feed to it will tend to make it run clockwise...
yes they look counter rotating eh andy, but what i mean is that i doubt if a tubby compressor will spin very effectively if you were to blow into it, they have tried hybrid electric tubby,s tho :)
 

h701micra

Deactivated Account
a tubby "pressure" works centrifugally tho surely ? the air is thrown outwards around the edge of the impeller, the intake blades just feed it
very exaggerated by this gas compressor, but same principal

View attachment 25795
That's how they work indeed.... but as it spools up the draw from the intake blades is drawing from still or restricted flow (air filter).... so a decent built fan can provide a charge of air at the intake blades for them to draw in reducing the effort the turbo makes :).... if you look into too much detail its becomes confusing and difficult.... keep it simple its easy to see the benefit
 

h701micra

Deactivated Account
If I didn't see an improvement I wouldn't be banging on about it lets be honest :p its not theory its past experience

To aid my point @enuo @ frank.. sequential twin turbos work in the exact same way
 

frank

Club Member
the exhaust turbine is shaped like a waterwheel, and blowing into it spins it efficiently, but the compressor end has this narrow slit that the centrifugal bit feeds (arrowed, where is actually builds the pressure up)
if blowing into the intake had any effect, then high performance turbo,s would have big intake blades and a big entry eh :)

images.jpeg
 

h701micra

Deactivated Account
Not necessarily. That boils down to everything else like the engine in question, power output, power band etc then you go into maximising that setup. That's how building track cars varies from rally cars.
I'm not saying that this increaaed power or boost it merely reduced spool time
In a track car they use larger turbos for max flow/boost for peak power
Rally cars use small turbos that spool up quickly and average out across the rev range
I dont get involved much with engine setups but that's what I see on our builds

If providing an air flow to the intake didn't work the sequential turbos wouldn't work no?
 

Enuo

Glorified Electrician
yes they look counter rotating eh andy, but what i mean is that i doubt if a tubby compressor will spin very effectively if you were to blow into it, they have tried hybrid electric tubby,s tho :)
I know, was trying to give a rough explanation why :)
Exhaust pressure won't allow it
Theres still potentially a counter rotative force from it, even if the driving force from the turbine is much larger.
 

h701micra

Deactivated Account
A gentle slope won't overpower a car, still slows it down :p
Its too late for my poor brain to start again :p
I'm saying... turbo is constantly spinning... so air is constantly drawn. Turbine never stops to be counter rotated.

That's it
My brain has given all it has
 
I believe iv read up that if you have an actual turbo , and take the exhaust side of turbo off , and fit a motor it does actually work , which seams plasuable, youd have to make a flange for the motor and stuff and of corse find a suitable motor ,
 

h701micra

Deactivated Account
I believe iv read up that if you have an actual turbo , and take the exhaust side of turbo off , and fit a motor it does actually work , which seams plasuable, youd have to make a flange for the motor and stuff and of corse find a suitable motor ,
Aye. Aids exhaust flow. But it'd be a very fine line between helpful and a hindrance :) same as this fan thing of mine
 
OP
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J
Guys,

I had a play over the weekend and I've got the auto choke working.
I took the back plate off and it seems it was placed on wrong last time, so I let it warm up and behold... A working choke.
HOWEVER... My problem isn't solved, in fact it's worse!
Cold starts it tries very hard to cut out for about 5 minutes now. From what I'm told it should increase the revs when cold but this isn't happening.

So when it's cold, the revs are very low, but when warm (without a counter) i would say it's idling very high.

Any ideas folks?
 
High idle , may not be the carb , i had trouble with these two thingss which stopped my car from being able to tickover right

Small vacuum hose which goes from intel manifold to the bottom of the air filter box , if thats not plugged in it will not tickover ,

Doubt this is your problem but PCV valve not operational , but id say it would run rougher if that wasnt working

It could still be your carburator , and from your description its in reverse because choke should engage and increase revs while engine is cold and disengage and drop revs when engine warms up. If its not picking up revs then your choke isnt working ?
 

h701micra

Deactivated Account
My vote is vacuum leak

Autochoke partially blocks the entry of air to the carb so it runs rich to help it run whilst cool.

But an improvement in the choke will see a kick up from a potential vacuum leak
 
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