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Discussion Starter · #1 ·
Hello all,

I have a “normal” vacuum/fuel pressure gauge that I’d like to use for checking vacuum level. If it’s possible to do so with this gauge, where is the appropriate vacuum source to attach the gauge? I’ve tried all the vacuum hoses that feed into the pump and the hose that connects to the brake booster— none of them seem to work, I.e., the needle jumps around all over the place. I know that my engine is rock solid, so I have no reason to believe that there is a big problem that would be reflected by such abnormal action by the gauge. FYI, I’ve successfully used this gauge many, many times to check vacuum on carbureted American muscle cars. But as a neophyte Alfa Spica guy, I’m probably missing/not understanding something that’s probably obvious to you Alfa Wizards. 😉

Many thanks,
Bob
 

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Why do you want to check vacuum? It’s not useful for anything other than brake boost. Distributor is centrifugal advance, not vacuum. The only place to check is at brake booster but again, why?
 

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Discussion Starter · #5 ·
To maybe help with tracking down a (potential) vacuum leak? I tried at the booster, but what I saw there is wild fluctuations around 10 hg.
 

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But Mad North-Northwest
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Why do you want to check vacuum? It’s not useful for anything other than brake boost. Distributor is centrifugal advance, not vacuum. The only place to check is at brake booster but again, why?
A vacuum gauge is a quick, cheap, and easy way to diagnose a lot of engine problems:


radojko, I think you need a vacuum source that pulls from all cylinders to use the gauge, and most (all?) ports on the Spica cars only pull from one cylinder.

If you're trying to track down vacuum leaks, you can try spraying some carb cleaner around various joints. If the idle changes you've got a leak. Obviously be careful doing this as you're using flammables around a hot engine.
 

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if you fear a fire (which I dont but some do) an unlit propane torch will do the same thing -- crack open the gas, and point it all around the vacuum lines and fittings, etc.
 
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Discussion Starter · #8 ·
A vacuum gauge is a quick, cheap, and easy way to diagnose a lot of engine problems:

I get that, and that’s what I’m using — an external vacuum gauge
The tip of using an unlit torch is clever, and something that I CAN do… thanks!
 

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I use a port to Number 1 side of the Spica manifold which is quite steady....not so much for diagnostics but i have fitted a 123 Dizzy with vac advance.
 

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But Mad North-Northwest
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I use the same port on my GTV for advance. If it's like my car it's steady because, even though it only pulls from one cylinder, there's a small orifice in the brass nipple that serves to smooth out the pulses.

It works well for a distributor vacuum pickup but it won't really work for vacuum gauge diagnosis, I think.
 

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if you fear a fire (which I dont but some do) an unlit propane torch will do the same thing -- crack open the gas, and point it all around the vacuum lines and fittings, etc.
Starter fluid is fun to do that with to.

I worked at a Porsche/Audi dealer where the higher ups thought it would be great to put a huge picture window in the waiting room so you could watch your car being worked on. But the waiting room being in the corner and the window focused right up close to one techs lift. One day about a week after the dealer spent about 10 grand to do the window. Had to go through the concrete block wall. There were about 8 people in the waiting room. The tech started hunting down an intake leak with a can of starter fluid. Soon the engine and his arm were burning the residue of the starter fluid of will he stared off into space smoking his cigarette.

The waiting room erupted in screaming and yelling beating on the window and the customers freaking out. One lady broke down in tears on the floor. The tech finally looks up. Takes his head and bushes the fire out on his arm. Then blows out the fire on the engine with his mouth. Then smiles and waves at them and walks off.

The construction crew was there at 6:00 in the morning to board up the week old window.

There were rumors of a lawsuit at one point.
 
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But Mad North-Northwest
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Soon the engine and his arm were burning the residue of the starter fluid of will he stared off into space smoking his cigarette.
Or as I call it in my home garage, "A Typical Saturday"
 
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