TheSamba.com :: View topic - Weber 40 IDF or 44? Want to keep rpm low. What jets¿?

Thu Aug 14, 2008 2:34 pm

Please I need help choosing my carbs.
I already have a pair of 40s and a pair of 44 IDF.
I run a stock crank because when I built the engine I was new to performance vw and made that mistake. The engine was built years ago, but not used until now.
Now I realize that probably the engine will rev over the limit of the stock crank because of the cam (W120)
I was wondering if the 40s will keep the power band in a more useable range, or if the smaller carbs will be fighting against the cam.

My first intention is to mount the 40s, will they produce more power bellow 4500rpm??

what is the power band of the w120??

and finally, what jets should I try in each carb? venturis are 28 and 34

Thanks, any help would be appreciated :D

Here are my engine specs:

1914cc type 1
MOFOCO 042 heads, 40x35.5 (non port/polish)
8.0:1 compresion
Engle w120
CSP Super comp exhaust (not already bought)
aircooled.net SVDA distributor
STOCK CRANK

Thu Aug 14, 2008 4:22 pm

I'd stick with the 40's.

Fri Aug 15, 2008 1:03 am

neither the big valves or the cam are going to help intake charge velocity(low end TQ) , i would use the 40's with the 28's and a 1 1/2 header.

Fri Aug 15, 2008 7:35 am

The crank will work your case is going to not like you. Power band is 1500-6000 rpms. Either way the 40s or 44s are going to have to be jetted, (venturis changed?) etc to work correctly. The 40's will be more responsive at lower RPM. You might consider a Bosch rev limiting rotor from a T-4 bus or Porsche. Since its never been run you could install an Engle 110 cam.

Fri Aug 15, 2008 3:57 pm

perrib wrote: The crank will work your case is going to not like you. Power band is 1500-6000 rpms. Either way the 40s or 44s are going to have to be jetted, (venturis changed?) etc to work correctly. The 40's will be more responsive at lower RPM. You might consider a Bosch rev limiting rotor from a T-4 bus or Porsche. Since its never been run you could install an Engle 110 cam.

Well, the engine is in the car and by now I am not thinking in taking it apart. Maybe in the future, but then I will also change the crank for a counterweighted one.

The rev limiter is a good idea. Will it fit in the SVDA?

I will go for the 40s. What jets in them???

Fri Aug 15, 2008 7:25 pm

Just set your needle on the tach at about 5k.....and monitor your right foot.

Fri Aug 15, 2008 7:58 pm

50 idle, 120 main, 200 air is where I would start. Make sure the floats are adjusted correctly, or this will not work right.

Fri Aug 15, 2008 8:27 pm

The rev limiting rotor will fit.

Sat Aug 16, 2008 4:27 pm

Thanks for the replys!
I've already set floats, thanks for the jetting advise!