Weber IDA 40 vacuum source?

[Bergo]

Hi guys,

Thinking about adding a brake booster to my '74 911 with a 2.2T + weber 40's. Currently no vacuum source to run the brake booster, is it as simple as drilling and taping holes in the intake runners of the webers to get a vacuum source enough to operate the booster? Do I need to pull vacuum from all 6 cylinders and have an accumulator, or could I only pull vacuum off of one or two to minimize the number of rubber hoses running around the engine bay?

[pors1968]

You should use sporto intake .They already have vacuum ports

[1QuickS]

OEM intakes after 1967 have provisions for tapping for vacuum. PMO manifolds can be supplied with the vacuum ports tapped already.

[Bergo]

Originally Posted by 1QuickS

OEM intakes after 1967 have provisions for tapping for vacuum. PMO manifolds can be supplied with the vacuum ports tapped already.

not a bad idea, PMO 40mm intake manifolds will bolt right up to weber carbs?

[pors1968]

Yes they also have vacuum port.

[SCrescue]

PMO manifolds only have provision for pulling vacuum from a single inlet. It may be adequate for some applications, but I was skeptical that a single inlet could provide enough vacuum for power brakes, so I drilled and tapped all six inlets for 1/8" brass fittings and made a simple six into one manifold with vacuum hose and pvc tees and els to connect to the brake booster hose. The thin vacuum tubing is barely noticeable and brakes operate perfectly. I believe this is the better solution.

[KTL]

The single vacuum source on the left/1-2-3 cyl. manifold works fine. Usually need to install a check valve to make it work most effectively.



Commonly available 1/2" hose barb fitting works great to connect the hose to the manifold. I use a 1/4-18 NPT tap (7/16 drill bit) to thread the hole for a common brass plumbing adapter fitting available at your favorite home improvement store