Carb Jets/Inlet Manifold

[Cassie-Nova]

Hi all,

I'm looking to buy a Weber 32/34 carb to upgrade my 1.2 nova. I have the inlet manifold and am currently polishing up all of the ports so they are nice n smoooooooth.

Firstly, what else can i do to the manifold to improve it?

Mainly, what exactly is it that the Jets in a carb do? The carb im intending to buy is currently got its jets set to run a 1.6. Can i fit it to my 1.2 with the jets set for the 1.6 or do they really need to be re-jetted first? What types of places can do this for me? ie, any garage, or a specialists like Sanspeed or a performance/tuning garage??

Cheers guys!

Jim

[Snowface]

first unpolish that 'smooth' manifold. If you have it to smooth mate it can cause fuel to drop out of suspension in the mixture. Needs to be a bit rough still.

[Cassie-Nova]

eek!

Wen i say polish, i mean iv used my dremmel to remove all the old crap that had stuck to the inside of the ports. Is this wrong :?

[dunova]

You will need to have it re-jetted-any decent rolling road should be able to do this and set everything up to be spot on. I remember hearing that 800 grit wet'n'dry paper is a good grade to use on the inlet manifold ports, don't quote me on that though :lol:

Basically you just don't want them to be REALLY smooth, just rough.

[Cassie-Nova]

Any ideas on how much it would cost to get the carb jetted for the 1.2 then?

Is it a case of getting it jetted before i can use it? ie, can i fit it all and drive it down there running on 1.6 jets?

thanks

[dunova]

Should be driveable as it is, but will over fuel and not run too great. Not sure on prices, but i think roughly ?110 for an hour on the rollers and it shouldn't take more than an hour to setup.

[Cassie-Nova]

is it possible to fit the Jets yourself and then just get the engine Tuned? Rather than put it on a Rolling Road?

Cheers,

Jim

[dunova]

is it possible to fit the Jets yourself and then just get the engine Tuned? Rather than put it on a Rolling Road?

Cheers,

Jim

Yes you could but you'll have to find out what size jets you'll need. Also, which jets need changing, e.g main jets, auxilliary jets etc etc. I'm afraid i don't know a lot about it, but i'm sure someone on here will. Also, they can get it tuned 100% right on the rollers for performance, whereas a garage ?50 tune up won't be quite as good (although it'll run and drive as it should).

[Nick]

aye, as dunova said don't mirror polish the inlet ports - Like you see on "fast and furious"

having tooo smooth ports stops the air/fuel mixture from rolling and makes the fuel drop out of suspension, a slighly rough, but smoother port aids flow but keeps the fuel in suspension better

go to a RR to get it done, i've been qouted ?80 plus parts. for as long as it takes

[Cassie-Nova]

So what would i require them to be jetted down to then? 1.3SR jets? Or would i need it jetted to 1.2 ones? As i'm using a 1.3SR inlet manifold, i am sort of presuming i could run it on 1.3sr jets?

[polly]

what you want is for the exhaust ports to be as smooth as possible so that airflow is maximised and that none of the carbon to stick
inlets should be finished in 80 grit

[Adam]

So what would i require them to be jetted down to then? 1.3SR jets? Or would i need it jetted to 1.2 ones? As i'm using a 1.3SR inlet manifold, i am sort of presuming i could run it on 1.3sr jets?
I think you may be ok using 1300 jets.
I ain't an expert tho, you would have to see what a carb tuning place say.
But obviously your engine is still a 1.2, just with a 1300 manifold put on it.