[Verm1n]

Is it just a bolt off bolt on??
Is there any there any peformance difference

*can anyone help*
obviously if done, a few hoses would need to be blocked

reason why
snorkel is on drivers side
part of it hits the bonnet
carby probs to start with

OR wood it just be better to get it looked at???

[steve]

I have the 1.3 carby on a 1.6 motor. Also use the 1.3 carby manifold. all bolts up easy.

[steve]

and a quote from nissvit:

I know this isn't perfect tech but was an interesting day and am just hoping to share some new info

I borrowed a cool toy from work on the weekend - a five gas exhaust analyser - to try and sort out Steve's carby problem(s). Engine specs: Vitara 1.6 block, 8 valve vitara head, 1.3 sierra intake manifold and 1.3 sierra carby.

Before checking the exhaust gas we serviced the car to make sure it was close to running ok. service specs - new leads, 0.8mm plug gaps - timed to 8 degrees.

Mixtures were checked at idle (easily adjusted via idle mixture screw on side of carby) and at cruising revs (approx 2800 for the sierras) - not so easily adjusted as this mixture is dependant on the primary fuel jet which feeds from inside the fuel bowl of the carby.

What we found: with the standard jets (0.99mm in primary & 1.05mm in secondary) the engine was way lean at cruising rpm.

geek bit
Nominally perfect air/fuel ratio is 14.7 parts air to one part fuel which is otherwise known as a lambda ratio of one. Steve's car was at about 15.3 parts air to one part fuel which had a lamba ratio of 1.08.. so it was lean.
end geek bit

We found a reference vehicle - (its great having neighbours with totally stock cars) and checked the mixtures at similiar revs - with the results that the stock sierra had fairly consistent lambda ratios of about 0.96 (just a little bit rich).

To achieve these exhaust mixture ratios in Steve's car we used a 1.05mm jet in the primary and then a 1.42mm jet in the secondary.
With a carby clean and these jet sizes we acheived a lambda ratio of approx 1 at idle, and 0.93 at 2800.. The reference books books I was using (bosch handbook) reckons that max torque is acheived at .9 lambda exhaust mixture so I was happy with the 0.93.

As this was effectively a no-load test we didn't get to test the secondary circuit reading but will see how this goes for now. The 1.42mm jetted secondary now allows you to feel the car accelerate at 80k when you open the second throat, which it didn't want to do before.

So in short form - if you are running a 1.6 bottom end with sierra carby, and it feels a bit doughy, try a 1.05mm jet in the primary and (if everything else is basically the same as Steve's) you will have the primary throat mixture about right.


cheers,
Chris

[joeblow]

PEOPLE...........................sierra carbs are shite!



use a vit carb and tune to factory specs and you will be blown away with the reliabilaty.

[2stroker]

On top of what joeblow just said, the internal bore size of a vit manifold and carbie is bigger and flows a lot better. Steve what did you do about the mismatch of size at the manifold gasket did you port the manifold out to match the head?. Dyno figures between the two aplications would be interesting, I am guessing that up in the revs the sierra carb/manifold would start to restrict the engine.

[steve]

port the minifold? holy crap that's a bit fancy!

yeah i'd be interested to see how much difference it makes. I may be a bit negative but i don't know if i'd notice the difference? A bit like adding extractors to a hilux

[2stroker]

Steve from what I remember there is about 4mm difference in the inside diameter of the sierra manifold to a vit manifold that is a big step when the sierra manifold is bolted to the vit head.

The performance of an engine is greatly effected by its ability or inability to flow air/fuel mixture, if someone suggested that you reduce the amount of air that can enter your air cleaner by bolting a plate over it with a 4mm diameter smaller hole would you do it.

When performance engine builders want to extract horsepower amoung other things they get the engine flowing better with larger valves, port matching, changes to cam lift and duration. This makes the biggest difference you can get in horsepower gain apart from forced induction.

I rekon you could be cheating yourself out of power. I know a guy that purchased a vit powered sierra that seemed pretty ordinary, turned out it had a 1300 head, manifold and carbie on it, he fitted a vit head manifold and carbie and it really came to life.

[steve]

yeah i know what ya mean. I did have a 1.6 carby and 1.6 manifold on there... it was all stock 1.6. Maybe the carby wasn't set up right but there wasn't much difference with the 1.3 carby/manifold. I'm not too concerned as i don't use the car much so haven't done much testing. I still have the 1.6 carby ad manifold though.

I just mean like, when people talk about a big difference, i want a BIG difference and if it's just a little i wont go to much effort. Not complaining at all , just saying.

[jesterracing]

Slightly off topic, but is it possible to work it back the other way? Ie put the better flowing 1.6 carby on the 1.3? Power at the bottom end isn't an issue if it'll make it go harder

[joeblow]

jesterracing wrote:

Slightly off topic, but is it possible to work it back the other way? Ie put the better flowing 1.6 carby on the 1.3? Power at the bottom end isn't an issue if it'll make it go harder

yes it is..........is the first thing i do on any 1.3.

[Verm1n]

thanks heaps fellas... i've just had heaps of probs wit it
i prob will end up puting the 1.3 carby n' manifold onto it
see how that runs and go from there

[Rockhopper]

Out of curiosity Joe, my Aisin carby is problem free, but might consider fitting the Vitara manifold and carby if it means it'll give the little 1.3 a bit more grunt. Is there any noticable differance on a 1.3?

[jesterracing]

joeblow wrote:

jesterracing wrote:

Slightly off topic, but is it possible to work it back the other way? Ie put the better flowing 1.6 carby on the 1.3? Power at the bottom end isn't an issue if it'll make it go harder

yes it is..........is the first thing i do on any 1.3.

thanks mate, now all i have to do is find one. does the 1.6 carby fit the 1.3 manifold or do I need the manifold as well?

[Verm1n]

well i've decided to keep the vitara carb but will put the sierra airbox on

[joeblow]

jesterracing wrote:

joeblow wrote:

jesterracing wrote:

Slightly off topic, but is it possible to work it back the other way? Ie put the better flowing 1.6 carby on the 1.3? Power at the bottom end isn't an issue if it'll make it go harder

yes it is..........is the first thing i do on any 1.3.

thanks mate, now all i have to do is find one. does the 1.6 carby fit the 1.3 manifold or do I need the manifold as well?

same bolt pattern between the two.

[jesterracing]

sweet as. anyone got a spare 1.6 carby lying around?

[jamienoble]

x2 i want wone aswell now mine has been playing up a bit!