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Discussion Starter #1
Good Afternoon,

I have 1994 Alfa 33 with Carbs Dellorto fitted with Original Dual Carb Airfilter but K&N.

I wanted to add a Vacuum Gauge to see how the car is running but when I connect it to the Distributor Vacuum Advance (LH Carb Outlet) I only get 5 - 10 mmHg when i accelerate and as soon as the pedal it let go the vacuum drops !

Now I was going to use the Vacuum from the Power Brake but the Pipe it Plastic and the connector form the Manifold is Huge maybe 1cm diameter so I have no way to T it with what I have.

Any Suggestions and anyone knows why the vacuum inst so powerful on the Carb side ?

Appreciate the Help.

Regards,

Keith
 

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Good Afternoon,

I have 1994 Alfa 33 with Carbs Dellorto fitted with Original Dual Carb Airfilter but K&N.

I wanted to add a Vacuum Gauge to see how the car is running but when I connect it to the Distributor Vacuum Advance (LH Carb Outlet) I only get 5 - 10 mmHg when i accelerate and as soon as the pedal it let go the vacuum drops !

Now I was going to use the Vacuum from the Power Brake but the Pipe it Plastic and the connector form the Manifold is Huge maybe 1cm diameter so I have no way to T it with what I have.

Any Suggestions and anyone knows why the vacuum inst so powerful on the Carb side ?

Appreciate the Help.

Regards,

Keith
Hi,

It is designed this way, because the vacuum should affect the advance only at closed / part throttle operation,
to prevent detonation.
 

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Discussion Starter #3
Good Afternoon,

Thanks for the info, so where is it best to put in a vacuum gauge ? The Power Brake Vacuum ?

Thanks & Regards,

Keith
 

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Well, power brake vacuum is taken from only one intake port,
so I guess the vacuum readings might be still weak. Anyway
it may worth a try.

For the best results I think the vacuum should be taken from
all intake ports with some sort of thin union, then the gauge
should be connected to this union.
 

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Discussion Starter #5
Thanks for the Info, I notice fluctuation (Rapid) when I press the Gas Pedal but when driving steadily with my foot still on the pedal I get -0.2 bar constant but then goes as soon as I leave the gas. Kinda a odd way to notice how much fuel you're pushing I guess !!

Thanks Again !
 
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