TheSamba.com :: View topic

Wed Aug 20, 2025 12:54 pm

Is there ever a situation where you would have on smaller venturi? I had a set of drla’s and it had one smaller vent. I’m not sure if it was positioned on #3 cylinder. These carbs been sitting and I’m thinking of using them, again. They were bought used and where once on a race dirt buggy. I used them about 30 years ago and never noticed the venturi.

Wed Aug 20, 2025 3:42 pm

NJ John wrote: Is there ever a situation where you would have on smaller venturi? I had a set of drla’s and it had one smaller vent. I’m not sure if it was positioned on #3 cylinder. These carbs been sitting and I’m thinking of using them, again. They were bought used and where once on a race dirt buggy. I used them about 30 years ago and never noticed the venturi.
I've seen it on a single side draft Dellorto carb, along with staggered jetting.

Never seen one smaller vent of the four on a set of DRLA's.

Wed Aug 20, 2025 3:46 pm

If it’s used a single center mount and on an open intake… ( theres a name for it and my dumbass brain cant think of it ).
I have a 45 DCEO with different sized chokes, venturis, jets, and velocity stacks too. It’s on a draw-through turbo setup.
Set up like this you can stagger when the mains come in, tuning one throat for lower rpm and the other higher.
Dont see how itd do anything but cause problems run as duals though. Maybe someone put it in and didnt realize it?

Wed Aug 20, 2025 4:21 pm

I’m kinda thinking it was just done by mistake.

Wed Aug 20, 2025 4:39 pm

BFB wrote: If it’s used a single center mount and on an open intake… ( theres a name for it and my dumbass brain cant think of it ).
I have a 45 DCEO with different sized chokes, venturis, jets, and velocity stacks too. It’s on a draw-through turbo setup.
Set up like this you can stagger when the mains come in, tuning one throat for lower rpm and the other higher.
Dont see how itd do anything but cause problems run as duals though. Maybe someone put it in and didnt realize it?
Yup, that was the setup I saw/worked on last September. It just had staggered jetting not the vents and velocity stacks.

Of course after we rejetted the carb. The owner turnt up the boost to max and fried a piston and head in short order.

Wed Aug 20, 2025 5:14 pm

Probably a mistake, BUT

it's ok if the main jet matches

4.1 times vent size
based on the REAL size, not the imaginary size

Vents ARE jets, and just like all jets, it's best to measure them instead of ONLY going by the size marked on it.

Wed Aug 20, 2025 8:01 pm

67rustavenger wrote: BFB wrote: If it’s used a single center mount and on an open intake… ( theres a name for it and my dumbass brain cant think of it ).
I have a 45 DCEO with different sized chokes, venturis, jets, and velocity stacks too. It’s on a draw-through turbo setup.
Set up like this you can stagger when the mains come in, tuning one throat for lower rpm and the other higher.
Dont see how itd do anything but cause problems run as duals though. Maybe someone put it in and didnt realize it?
Yup, that was the setup I saw/worked on last September. It just had staggered jetting not the vents and velocity stacks.

Of course after we rejetted the carb. The owner turnt up the boost to max and fried a piston and head in short order.

One thing ive learned, you cant really complain about customers that do dumb stuff and are willing to pay for their mistakes to be fixed.