weber carb tuning

[deceiver]

got my weber/intake from festiva motorsport - it was the last one.

put it on there and it's having lots of strange behavior..

will not idle, when I get to to stay at a steady rpm - very rare - it has a stumble like too much fuel or weak spark at 2000rpm.. then it will randomy fly up to 4500rpm and die.. any thoughts on this?

stock b3 besides the carb.

[ajb999]

is it idling at 2000 rpm's? that's pretty high unless carbed are that much different than efi when idling. mine is efi and the highest it idles at is 1200 when pretty cold.

[deceiver]

no, it won't idle.. it dies if it goes below 2000rpm, but I can hold it at that rpm if I hold the accelerator open.

[Dave G]

Did the engine run OK before the new stuff went on?

[syed3000]

as far as I know, in weber, u need to change the change the nozzles to fit them according to your usage, since it is not like regular carby where you turn screws to adjust the amount of fuel and air. So contact the seller and ask him about the proper jet nozzles for your engine.

[deceiver]

vacuum

This was caused by vacuum leaks around base of the carb.

air/fuel is adjustable on the weber.

[syed3000]

I see
gud to know u tracked your problem
so do you mean to say that weber carb has screws for the adjustment?
which weber carb are you using? DECOE 38 , 45 or some side drafts version? maybe your model is different
Also tell me how much difference in acceleration and top speed you got after installing this weber carby???? How much it costed ya? and how much fuel consumption increased?

[deceiver]

The webber is a 32/36 DGV, this is the current setup:

primary / secondary
idle 60 / 50
air control 170/170
main 140/140
2.5 turns out for the a/f adjustment

runs real rich, I need to order up some smaller jets. going to try 50/50 for the idle and 130/130 for the mains.

Acceleration is about the same, maybe a little less b/c of the tune.
The goals of the project were to get a good idle and remove vacuum leak issues.. those have been met with gold stars.

note: I did have to idle up quite a bit (1400rpm) to support the headlights and a/c load on the motor. with full load it's steady at 850rpm

[syed3000]

you mean by getting a weber carby, no difference in acceleration or top speed? just stability on idle rpms?

[deceiver]

correct, with the wrong tune, you get nothing, or less, I expect that it might be a little faster with the right tune, but not anything noticable.. the carb is very over sided for the job - it flows 300cfm.

if you look at the top of the stock carb, the opening of the choke plate will give you an estimate fo the secondary on this carb.. it's huge.. bigger than one of the barrels on my 650cfm holley.

[syed3000]

ahhh you are right but yours carby is 32/36 DGV Webter right?
I was thinking abt weber Decoe 45 since that one is a race series carby. Do you think it will gain better acceleration and top end?

[deceiver]

not much if any.

[mooseheadc]

not much if any.

Just too big.

Overcarbing works on some motors, but that 1.3
only needs around 100CFM at 5k.

this means the carb won't work at being streetable.
Webers are better than Holleys at reducing midrange bog,
but going that big is too much to handle

And your MPG will suck.

unless you build a sealed box and then run a blower, you won't get any use from too big a carb bore, and plan to spend much of your time spinning around redline.

[syed3000]

so which one is the best carby for our 1.3L festies? the stock one or some other for street as well as red line racing use too like once in a while???

[mooseheadc]

so which one is the best carby for our 1.3L festies? the stock one or some other for street as well as red line racing use too like once in a while???

Were you in the States, I'd say check up with the HotRod guys
to find a Stromberg 97 or Carter YF, as they flowed around 150CFM,
and I find them easy to tune vs the Webers, or anything else, really.

For your case, I'd say look around for some Mikunis off of a bike
with a 38 or 40mm venturi, or go for the multicarb look and get a couple
26mm units