carb change....now its not right!

[curtis]

Hi all,

I bought the sunny 1.3 carb from Speedle, which is great!
Put it on the car and it was running fine.

Speedle will probably answer this hopefully!

the problem is that if i floor the accelerator the car will judder and after about 1.5 seconds it will accelerate fine.

Also in top gear (4th) if im doing about 45-50....and then floor it (i no there won't be much acceleration) but it just judders and stays at the same speed!

What wrong? is it overfeulling or something?

thanks in advance.

 

[Speedle]

thats very odd mate, as it seemed to run perfectly on mine and the carb is very clean so shouldnt be judering.

however! now i think about it...

i was running my car with the timing advanced quite a bit and also i only ever run the car on high octane fuel, i reckon if you advance the timing about 5 degrees it should run perfect. of course every engine is different so i may be overfueling ever so slightly but sor tthe timing out first thats the only differnece between how your car is setup and how mine was

and 97 ron fuel is a must!!!!!!!!

 

[curtis]

ok thanks, ill have a go when i get home....why is higher octane a must?

 

[Speedle]

if you advance the timing and use high ron fuel then it will give you more power (thats the theory) and k10s generally run quite retarded timing, running the timing advanced on normal petrol will make it pink/flatspot and generally run crap. the micra handboook says you should be using 97 so make sure you do!

goto sainsburys for it its only ever an extra few p from them and you get nectar points too

 

[curtis]

we don't have a sainsburys, but tesco are selling 99 octane...which is what the british racing team use apprently?!?.....hummm

 

[Speedle]

aye thats good stuff mate, its a shame you dont live closer as i would have liked to have set it all up for you really

 

[frank]

speedle

i think the 4 speed k10.s are low compression but yes s/u petrol might help if its overadvanced
you can,t expect a carb off a differant model to be jetted perfect tho !

 

[curtis]

well ill do the timing and see what happens (big explosion over the west midlands! )

ill get a longer throttle cable as well....becasuse its really stretched...i take it that other nissan throttle cables should fit? what about the sunny one?

 

[joesouthgate]

The higher the fuel octane the more resistance it has to pinking (detonation). It doesn't make the car run better but if ur timing is advanced then it will be more likely to detonate, which is why you would run higher octane. (Just did a whole unit on this at college, knew it would come in handy! )

 

[curtis]

lol thanks!

 

[Speedle]

speedle

i think the 4 speed k10.s are low compression but yes s/u petrol might help if its overadvanced
you can,t expect a carb off a differant model to be jetted perfect tho !

i know that mate, but it ran pefectly on my ma10 lump and the only diffrence between the two of our cars is that i advanced the timing on mine.

 

[ollyc98]

The 4 speed is sommat like 9.5:1 and the 5 speed is 10.3:1 iirc so that could make a difference, however timing will sort that out if that's the case.

 

[Speedle]

sounds about right olly

 

[curtis]

i have advanced the timing 5 degree...also the car is full on 99octane fuel....this seems to have cured it....slight power difference in 1st and 2nd....but top end is slower.....it doesn't like going over the 80mph mark (private road of course )

 

[daveeeeee]

hmmm why would the four speed k10s have lower compression, sorry if thats a dumb question

 

[frank]

daveeeeee

so that they could run on the old 2 star petrol

 

[daveeeeee]

ahhhh makes sence