Dr. 914

Please we are always here for free detailed 914 tech advice

mturner7

Hi Everyone, This vacuum connection to the weber carburetors has been talked about 100 times, but I need to address it again.

CAR/Engine:
1) Porsche 914-4: 1975 1.8L big bore build, dual IDF 40 Carbs
- I have Weber 40 IDF 19 's with no vacuum port

2) I have a Pertronix 1 SVDA Distributor, 12 VOLT with electronic points

3) I have two sets of intake manifolds
- One set has a port already drilled and plugged see photo
- The other set does not have a hole/port

4) Since my new Pertronix 1 SVDA Distributor, 12 VOLT has the combination of centrifugal and vacuum advance installed. Can I just remove the plugs in the intake manifold and add the vacuum line with a "T" back to the distributor?

5) That's the way it is connected in my 1974 Porsche 914-4 2.0L car, except the car has dual weber 44 IDF's with a vacuum port on the bottom of the carb itself.

6) Please help, I'm in the middle of my build and coming close to installing the carbs, intake's, and distributor.

Question #2
I have two sets of intake manifolds, the holes that connect to the carbs are different on the two sets.

- 48mm for the short ones
- 40mm for the long ones

The 48mm ones were on the engine with the weber 40 IDF's
The 40mm ones were on a car with Weber 44 IDF's

The 48mm ones have the vacuum port drilled and tapped.

Will it matter which one I use with my weber IDF 40--> 40mm hole or 48mm hole?

Thx -Monte

mturner7

Weber IDF 40 with out vacuum ports, need to add them!

Dr. 914

always match intake to carb size for a smooth unstepped route into the combustion chamber. Builders try hard to match the porting as not to disturb the mixture.

Full centrifugal advance is the way to go with carbs no vacuum needed the port that is plugged is usually a place where one can get vacuum for power brakes