15 replies to this topic

[md7708]

im quite new to the tuning game, 

ive got a 1275 sprite, i recently changed the spark plugs and the old ones were white indicating that the engine was lean.

so i fitted a AEM sensor and gauge (which i had been eyeing up for a while) to possibly help me tune the car 

 

took a drive and it was indicating high 15's 16's (the gauge does tent to bounce about a bit)

started ritchening the mixture and ive got it to the point where i put my foot down its nicely sits mid 12's 13's  it also sits like this if i'm just cruising (not going past 2000 RPM)

 

however when i get up to 65-70 and stop accelerating it drops right down to 16's 17's 

is this normal? because i have stopped accelerating it reads lean?? 

i would have thought it would have stayed around the same mark roughly  

 

ive got the standard carb Hiff38 i believe

with a richer needle the garage fitted for me after i fitted my ram pipe and straight through exhaust 

 

and the sensor is fitted just before the gear stick 

 

Thanks for reading this if you did ;) 

 

Mark 

[Turbo Phil]

When the engine is under load like hard acceleration you should be looking for 12.5 to 13-1, part throttle steady cruise shhould see you around 15-16-1. So it sounds about right to me.

Phil.  

[md7708]

Thank you :)
had me slightly worried when I actually saw the numbers just dropping off

[lrostoke]

this is worth a read

 

http://www.terryhunt.../picsb/pics.htm

[ACDodd]

At part throttle cruise I usually aim for 14:1. This way you get a responsive no misfire smooth part throttle running.

Ac

[md7708]

So just need to richen it up a bit

Also what should the car be siting at while idoling?

Mark

[md7708]

Thanks irostoke that was an interesting read :)

[mini13]

yep that ddoes sound about right,

 

also turning the mixture screw will only really change the mixture at idle, to richen it up when driving you need tp chaange needles or start fileing them.

[ACDodd]

About 13.6 to 13.8:1.

Ac

[grumpy dad]

Hi 

can you give us a link to what you used 

and what the cost was 

thanks

 

http://www.aemelectr...-fuel-gauge-25/

[Ethel]

yep that ddoes sound about right,

 

also turning the mixture screw will only really change the mixture at idle, to richen it up when driving you need tp chaange needles or start fileing them.

You are just lowering the jet. Say you lowered it by 1mm then the fuelling will what you would have got with 1mm more piston (and needle) lift throughout the entire engine load range. Unless the needle is parallel sided, or out of the jet, you will get fuel enrichment, but it may well be by a different amount - the proportion of area increase being at the square of the change in radius.

[mini13]

Yes, but you know as well as I do the change will be negligable.

[md7708]

Hi 
can you give us a link to what you used 
and what the cost was 
thanks
 
http://www.aemelectr...-fuel-gauge-25/

http://item.mobilewe...Id=300976513214

That's the kit I bought, came with everything I ended up taking the exhaust off and welding the bung just before the gearstick

[md7708]

Ah right I thought that the idol was changed with the idol screw on the top of the carb and the range was changed with the mixture screw on the side of the carb

So I need a new needle to get the mixture right?

[lrostoke]

or polish the needle as described in the link I provided