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Setting A Twin Hs2 Carburettor

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#1 Shak

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Posted 20 January 2024 - 08:13 PM

Dear Experts and Gurus,

 

I have recently purchased a classic leyland mini 1974, it was standing for 2 years, i got it running and noticed rust was in the tank and TWIN HS2 CARBURETTORS,

 

So  i stripped them cleaned up everything put it back together and now i just cannot get it to run smooth without stalling, jerking and or cutting of very randomly.

Please can i have some detailed documents or steps to get it running smooth?

Additional info:
Needles are not bent

New Plugs
Fresh Fuel
Filter

Oil

new points and condensor.

Link to the car and how its sounding etc.

https://streamable.com/qla9vt

(video will expire in 2 days)

 

Thanking you! :gimme:
 



#2 nicklouse

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Posted 21 January 2024 - 10:57 AM

First thing first are they matched? During your rebuild of them just you check and set them so they behave exactly the same?



#3 Lplus

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Posted 21 January 2024 - 11:39 AM

Dear Experts and Gurus,

 

I have recently purchased a classic leyland mini 1974, it was standing for 2 years, i got it running and noticed rust was in the tank and TWIN HS2 CARBURETTORS,

 

So  i stripped them cleaned up everything put it back together and now i just cannot get it to run smooth without stalling, jerking and or cutting of very randomly.

Please can i have some detailed documents or steps to get it running smooth?

Additional info:
Needles are not bent

New Plugs
Fresh Fuel
Filter

Oil

new points and condensor.

Link to the car and how its sounding etc.

https://streamable.com/qla9vt

(video will expire in 2 days)

 

Thanking you! :gimme:
 

Running way too rich at tickover.  You can see the black smoke. Check the plugs and see if they are all black or just 1/2 or 3/4

 

Have you set the idle mixture using the jet nuts? That's what those nuts are for. start with the jet tops two turns below the jet bridge and adjust up or down for weak or rich

 

Are the choke levers stuck and holding the jets down?  Did you centre the jets in the carb base so the needles go down the centre of the jet and don't stick?

 

Is one or both of the needle valves leaking leading to high fuel level?  That said there doesn't seem to be any fuel leakage on the top of the fuel bowls


Edited by Lplus, 21 January 2024 - 11:41 AM.


#4 Shak

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Posted 21 January 2024 - 12:05 PM

@Lplus,

Thanks for your advice, 

Plugs are black.

I have been adjusting the idle mixture using the nut at the back of the Carb,(i can adjust it to a point were it would stop black smoke out the end, however then it cuts off sometimes and jerks)
The choke cable is removed so im guessing it cannot be stuck?

The left Bowl over fills with fuel it seeps out the gasket when i put the keep on and the facet pump send fuel to the bowl.
The need valve is new so what's causing the over flowing? pressure of the facet pump?

Thanks


 



#5 Shak

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Posted 21 January 2024 - 12:07 PM

First thing first are they matched? During your rebuild of them just you check and set them so they behave exactly the same?

Hi Nick, i assume they matched previously not by myself though, they look identical and was built by a very clued up guys who is unavailable to reachout too.
What can i do to establish if they are "matched"? 



#6 Lplus

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Posted 21 January 2024 - 01:01 PM

@Lplus,

Thanks for your advice, 

Plugs are black.

I have been adjusting the idle mixture using the nut at the back of the Carb,(i can adjust it to a point were it would stop black smoke out the end, however then it cuts off sometimes and jerks)
The choke cable is removed so im guessing it cannot be stuck?

The left Bowl over fills with fuel it seeps out the gasket when i put the keep on and the facet pump send fuel to the bowl.
The need valve is new so what's causing the over flowing? pressure of the facet pump?

Thanks


 

The lack of choke cable does suggest the levers should be fully up, but it's worth checking they are all free and the jet moves up and down freely.  After each jet nut adjustment I tend to push up on the jet base to ensure it's seated properly.

 

The float needle can still leak even when new if a tiny speck of dirt/rust gets in the seat.  Remove and flush through if you can. a filter would be a good idea if you can't clean/replace the tank.  A flooded float bowl will most certainly cause rich running, and if you try to adjust for it with the jet nut all you will do is make the part throttle mixture too weak.  The fact the only one needle seems to be leaking suggests the pump is not to blame, though I don't know if facet pumps produce a high pressure. Dealing with this should be the first step.

 

When you stripped the carbs down, did you remove the jets and jet locating nut ( the large nut above the jet adjustment nut)  If so then centring the jet must be done the ensure the needles can't stick in the jet due to being offcentre.  A good check on centering is to lift the piston about 5 mm and let it drop. If it drops onto the bridge with a slight click then it should be centred enough.

 

Matching means they rise at exactly the same rate under equal vacuum application and fall back at the same rate when vacuum is released.  ( rough check, Lift the piston and see how hard it is to lift, lift each piston 10mm and drop and see if they drop at about the same speed.

 

It does seem happy enough when revved, so it has to be the idle fuelling causeing the problem.


Edited by Lplus, 21 January 2024 - 01:03 PM.


#7 Shak

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Posted 21 January 2024 - 07:12 PM

Thanks, im going to first check the bowl over flowing issues, then do all the tests you have mentioned, much appreciated!

will be posting an update as soon as i get this done!


 

 



#8 Shak

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Posted 21 January 2024 - 07:31 PM

so im doing research elsewhere and i came across these legends, wow never new about the air in fuel issue.

https://www.mgexp.co...g.776978/page-2







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