Race Engine Forum UK

Hi Guy,

After many hours welding I am now about to rebuild my X1/9 to modified sprint/hillclimb spec to compete in the under 1400cc catagory

So I am ready for spring I am refitting the original 1300 engine in my Fiat X1/9 and want to fit my twin Weber 40 DCNF carbs. The engine is for now completely standard apart from the carbs, CSC 4 branch manifold and system. I would be very grateful if you could give me some advice on appropriate jetting for the carbs. The setup at the moment is :-

Choke - 30
Main jets - 140
Idle jets - 65
Emulsion tubes - F36
Air corrector jets - 210
Accel pump jets - 35
Aux venturi - 2.5
Needle valve - 1.75

To be honest I have no idea what these where jetted for so don't want to try running the 1300 without first getting a reasonable baseline to work with.

I have aready read and taken your advice for a Silver Top fast road pump with no regulator.

Any advice would be gratefully accepted!
thanks as always
Guy

On another note I have found a company that is suppling X1/9 manifolds as well as many others thought it might be of interest

LINKS BY PERMISSION ONLY READ PROTOCOLS
GC

Sorry about the link Guy

missed that in the rules. Won't happen again. Just thought it would be useful to all members finding it hard to get a manifold for there project. I haven't used the company myself as my carbs came on a old manifold like the one in the photo.

Apologies again

Guy

It's OK. Remember I'm only a PM away though!

GC

More later..

Original standard X19 1300 on 40DCNF

Choke - 30 - OK but a bit small - 32 better
Main jets - 140 - too big (rich) go 120
Idle jets - 65 - too rich - go 45
Emulsion tubes - F36 - no - use F21
Air corrector jets - 210 - maybe a bit big (lean) go 200
Accel pump jets - 35 OK

The performance will depend to a very great extent on the layout of the ex manifold and back pressure in the silencer.


GC

Many thanks Guy,

I have started ordering the parts. The F21 emulsion tubes are being difficult to source. I have tried Webcon who no longer supply the F21 and supersede onto the F22. The difference according the Webcon is the F21 tube has a diameter of 5.7mm and the F22 is a 6mm diameter. The hole layout of the two tubes is the same. I have also tried the usual Google search but nothing there either.

What do you advice? Or do you have any F21's that I could purchase from you?

Regards

Guy

You can certainly use F22, no worries, they are interchangeable with F21.

GC