11 replies to this topic

[herdy]

Is 2 and a half turns in relation to the mixture screw a lot. Only reason i ask is because a few months back my dad adjusted my mixture 2 and a half turns and it now drinks fuel like its going out of fashion. It's not been pulled up on it's MOT but i'm just curious because it's costing me no end in fuel. It's a '92 mayfair 1275 running a HIF38.

Thanks, Ben. 

[TehMarchant]

Have you Popped your plugs out yet for a look?

Is the inside of the pipe deep black maybe wet?

Is their a strong smell of unburnt petrol?

[herdy]

no, there's no smell of unburnt fuel, i've not checked the plugs. which pipe do you mean? the one going to the carb or the over flow?

[IainNeon91]

You should really run a HIF44 on the 1275 to get the most performance, but that's up to you...

 

Regarding your question, what was the reason he changed the mixture? Did you add a 'stage 1' kit to your mini? 

 

If this is the case then you will see you will use a bit more fuel than normal, it's only until you get it properly calibrated on a rolling road that you will have the power and using a correct amount of fuel.

 

If this isn't the case, check your fuel lines for leaks.

 

Iain

[herdy]

I'm intending on putting a HIF44 on it but at the moment the engine is completely standard. I've got no idea why he did it. is 2 and a half turns a lot then?

[TehMarchant]

I ment the exhaust, but Neon has the right Idea, you should get her on a rolling road to her sorted properly.

[IainNeon91]

I'm intending on putting a HIF44 on it but at the moment the engine is completely standard. I've got no idea why he did it. is 2 and a half turns a lot then?

On my HIF38 an 1/8th of a turn made a difference once i had reached the 'sweet spot' any further than this point, you could see less MPG, not a dramatic amount though. 

 

There isn't any fuel coming out around the bottom seal of the carb is there? 

[Dan]

2 1/2 turns is loads.  There is a total range of 1 turn where the mixture is roughly right and the car will idle nicely, and the normal level of tune would be 1/3 of the way through that range from the lean end.  

[herdy]

jesus, i dread to think how much fuel i've wasted if that's the case. i wonder what i'm doing tonight. for what its worth, the mini has been a lot more eager to go since

[Dan]

  Just because it needed a lot of adjustment doesn't mean it isn't right though, it may have been drastically wrong before.

[herdy]

i had a gasket between the carb and the manifold fail so that's the reason for me taking the carb off and what not. 

[Ethel]

You'll find info online on setting up SU's. look for "University Motors", an American MG specialist, on Youtube. You need the ignition set up properly first, and the engine warmed up.