adding a 34 ADF, vacuum question

[howelljd]

I traced out the path for the distributor advance on my 28/32 ADHA with a green wire:

It looks like the "dimple" is the point to drill out into the small cavity (about 6mm diameter) immediately below the hose nipple. A subsequent pathway - quite small - is drilled via the 6mm cavity into the throttle assembly above the butterfly. Note that my 28/32 ADHA actually has a series of holes for this ported vacuum provision. The 6mm diameter cavity must subsequently be capped with a plug.

Cheers,
Jonathan

[msjulian]

Thanks to Jonathan's pic I think I figured it out. It looks like I need to use a jet drill bit and drill a small hole in the upper portion of the port just below the port I am going to use for the advance.



This will come through the venturi above the plate thus making it ported vacuum



Then plug that port hole off and drill a hole to match the size of the hole where the vacuum port dead ends in to the small punch mark in the carb.





Finish by using that bit to open the port and add a brass hose nipple.

If done correctly, this will open the passage from the venturi above the butterfly to the port needed for the vacuum advance.

[bradartigue]

Thanks to Jonathan's pic I think I figured it out. It looks like I need to use a jet drill bit and drill a small hole in the upper portion of the port just below the port I am going to use for the advance.

That port you are pointing at is the wrong port. It's the smaller one just above it.

http://www.artigue.com/fiatcontent/carb ... orting.pdf

[msjulian]

You are correct. As I stated...

"drill a small hole in the upper portion of the port just below the port I am going to use for the advance."

After you drill the port BELOW to the vacuum advance port it will have to be plugged. This is the only way the it will operate correctly. If you don't drill and plug the lower port you will have no vacuum at all if your carb was not set up to use the vacuum advance port.

[bradartigue]

You are correct. As I stated...

"drill a small hole in the upper portion of the port just below the port I am going to use for the advance."

After you drill the port BELOW to the vacuum advance port it will have to be plugged. This is the only way the it will operate correctly. If you don't drill and plug the lower port you will have no vacuum at all if your carb was not set up to use the vacuum advance port.

You're right, I can't follow what you're saying, but so long as you can you're the one with the drill!