21 replies to this topic

[cotty]

hi lads can you give me heads up, for what red or yellow spring and what needle on hif44 1380 

Edited by cotty, 12 October 2023 - 04:02 PM.

[GraemeC]

What cam?

[cotty]

hi thanks for getting back to me it is the minispares evo 1 duration inlet 264 exhaust268 lift inlet 264 exhaust 289 does this help, with a brand new hif44 red spring and bdl neddle, no matter what i do i cant stop it running rich.

[StefanMini]

hi thanks for getting back to me it is the minispares evo 1 duration inlet 264 exhaust268 lift inlet 264 exhaust 289 does this help, with a brand new hif44 red spring and bdl neddle, no matter what i do i cant stop it running rich.

Use a red spring.
What oil do you use in the dashpot? Thinner oil will lean the mixture.

[Designer]

I am intrigued when anyone has a problem with there carburettors more often than not someone will ask what oil is in the Dash Pot of the problem carb whether it is to do with tuning, sticking or slow moving piston or whatever.

As SU Carbs supply a specific oil for Dash Pots surely that is what should be used. It is what I use.

[stuart bowes]

I thought it was more a case of choosing an oil per application, and varying it can have different effects

 

not that i'm any sort of expert that's just what I think I read at one point

 

haven't got to that point yet on mine

Edited by stuart bowes, 13 October 2023 - 11:31 AM.

[KTS]

the question is asked because the fluid that's being used has such a critical influence in the way the carburettor operates but often is not fully appreciated how or why

 

just because SU supply a specific oil for dashpots doesn't mean it will be the correct grade for every carburettor on every engine;  it may be right for a brand new carburettor that machined to exactly the design specifications, but is unlikely to be right for a 40year old unit (which might require an heavier grade)

 

Handy video from ACDodd 

 

Edited by KTS, 13 October 2023 - 11:43 AM.

[cotty]

hi guys the problem i have is i live in blackpool and i cant find anybody to tune my mini .if i lived down south i wouldnt hesitate and get ac dodd to sort it that guy is wizard.su oil is what is in the carb thanks guys anyway.does a lighter oil help my problem ?

Edited by cotty, 13 October 2023 - 01:44 PM.

[Designer]

the question is asked because the fluid that's being used has such a critical influence in the way the carburettor operates but often is not fully appreciated how or why

 

just because SU supply a specific oil for dashpots doesn't mean it will be the correct grade for every carburettor on every engine;  it may be right for a brand new carburettor that machined to exactly the design specifications, but is unlikely to be right for a 40year old unit (which might require an heavier grade)

 

Handy video from ACDodd 

 

 

 

Thank you KTS for your explanation. Fortunately our 35 year old Mini runs ok for our needs. Gentle motoring enjoying the fun of being in a Mini.

I am sure if we took her to AC he could improve on her performance.

[KTS]

hi guys the problem i have is i live in blackpool and i cant find anybody to tune my mini .if i lived down south i wouldnt hesitate and get ac dodd to sort it that guy is wizard.su oil is what is in the carb thanks guys anyway.does a lighter oil help my problem ?

 

impossible to say i'm afraid as there's lot's of different reasons why it might be running rich 

 

Let's start at the beginning :  what makes you think it's running rich ?

[cotty]

the oil smells of fuel through the oil filler cap?

[StefanMini]

Do you have a wideband installed to read the air fuel ratio?
And yes different oils in the dashpot can make huge differences. But as above watch some video's from AC Dodd to check some settings.
Is the carburettor rebuilded?

[sonscar]

I think you need to be more scientific than sniffing the oil filler cap.Over full float bowl can contaminate the oil and run rich.Avoid guessing.Steve..

[stuart bowes]

no matter what i do i cant stop it running rich.

 

just to clarify for people trying to offer suggestions, when you say 'no matter what I do' what is it you have done so far 

 

just so they can cross things off the list and follow the trail of what's happened to this point it's helpful to give as much info as you can

Edited by stuart bowes, 14 October 2023 - 06:57 PM.

[growlerbearnz]

Oil that smells of fuel could also be a leaky mechanical fuel pump.

An initial way of diagnosing a rich mixture is to look for black, sooty spark plugs. But as others have said, you need some real data: get a tailpipe sniffer on that thing and find out what's really going on.