Vacuum port

3

30-9

Well-known member
I only have on vacuum port on my Offy dual carb manifold.

Can I use it without a T for the carbs? I’m not sure if at idle there is a vacuum needed for the dual carbs.
 
What engine and dizzy ya running? You could always tap one if needed. If needed. 94 Carbs have a base vacuum hole, but really not sure what your asking?
 
I've never seen a 94 carb on a Ford with a vacuum port at the base. '49 to '56 94 type carbs had a port higher up for the distributor advance (loadomatic), but it was not actual manifold vacuum. A lot less.


Sal
 
What do you need the second port for? The old flatheads had two ports. One for the distributor and the other for the windshield wipers. Assuming that when you went with dual carbs, you would go to an electronic distributor.

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I disconnected wiper and use the Offy port for carbs. I have a bubba 11a distro and skip coil.

I want to attach a vacuum gauge to run some tests. As mentioned currently vac port is used for both carbs.
 
I thought carbs had vacuum ports as a source of vacuum for other purposes. Please explain why the carbs need to be connected to the intake manifold vacuum port.

I would disconnect the carbs from the intake and use the manifold port for the vacuum gauge.
 
The Offy vacuum port should go to the distributor vacuum brake. If you place a vacuum gauge there the vacuum will be the highest at idle 18-20 and decrease as engine speed increases. I would cap the Edlebrock vacuum ports if you place a vacuum gauge on the Carb port and increase engine speed the vacuum there should increase with RPM.
 
Terry said:
The Offy vacuum port should go to the distributor vacuum brake. If you place a vacuum gauge there the vacuum will be the highest at idle 18-20 and decrease as engine speed increases. I would cap the Edlebrock vacuum ports if you place a vacuum gauge on the Carb port and increase engine speed the vacuum there should increase with RPM.
Click to expand...

I did a very bad job describing what I wanted to do. For that I’m sorry. Think my old age is playing with my brain....

You are correct. The Offy vacuum goes to distributor. I wanted to know to run vacuum test, do I have to T this connection. Or can I disconnect the distributor and use the line strictly for the vacuum gauge.

Again thanks for your patience.
 
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