vacuum gauge

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Dec 12, 2012 | 03:51 AM

HillBillyBuddha

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Tuned

Joined: Jul 2011

Posts: 350

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From: Sacramento, CA

vacuum gauge

Not talking about setting timing here, nor the difference between ported v manifold, nor setting carb mixture screws.

What I'd like to know is just basic diagnostic stuff, valves, exhaust, etc...

Where do I plug the gauge into? Do I pull one of the hoses. Or is there bolt I remove to get manifold pressure?

Thanks,

Joel

Dec 12, 2012 | 07:37 AM

Shadowrider123

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I have the distributor running off manifold vacume. I use that hose.

Dec 12, 2012 | 10:49 AM

rustywheel68

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you'll need full manifold vacuum- as for where to get it- anywhere you can, i guess.

like shadowrider said- there may be a full manifold port on your carb (depends on carb). other potential options: transmission vacuum modulator (if you have an auto tranny), power brake booster (if you have power brakes), etc.

if you're really lucky, there's a "vacuum tree" screwed into your manifold with multiple ports on it.

Dec 12, 2012 | 10:52 AM

ratrace2

New User

Joined: Jul 2011

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Just "T" into the line. Autozone has a bunch of vacuum hose couplings and t's (white ones).
Get a little extra hose and there you go.

Dec 12, 2012 | 01:20 PM

HillBillyBuddha

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Tuned

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From: Sacramento, CA

Thanks guys, I've got an automatic transmission so I think I'll have to tap in there but it won't be so easy. All of my lines are steal, well I'm guessing that's what's under the rust. Not really sure they are set up right though, I have one line that runs from my distributor directly into my carb. My best guess is that the vacuum pressure for the distributor must come from inside the carb. Remanufactured motorcraft / autoline 2100 (or maybe 2150) with manual choke. I've heard that the carb vacuum is "ported" but I have to admit that I have no idea what that means other then that I'm not suppose to use that....

Anyway, I bought a few yards of rubber vacuum hose to replace the rusted steal line that's in there now. I figure I'll cut the steal line, leaving about an inch nipple on each side and slide the rubber hose over and clamp it down. While I'm in the process, is there a way to leave in a permanent vacuum gauge port or would that be prone to leaks?

Thanks for your help on this one,
Joel

Dec 12, 2012 | 01:52 PM

rustywheel68

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"ported" vacuum just means that there is no vacuum signal at idle (ie- when the carb butterflies are closed). as you open the throttle, the "ported" vacuum port begins to show the vacuum signal.

you are correct- the vacuum port on the Autolite 2100 is "ported vacuum", so you won't be able to use it in this situation.

Dec 12, 2012 | 02:12 PM

HillBillyBuddha

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Tuned

Joined: Jul 2011

Posts: 350

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From: Sacramento, CA

Thanks for the lesson on ported vacuum hoses, RustyWheel. So unless I find bolt in the manifold to check vacuum, it'll be a couple days before I get to changing the steel lines out. The steel lines just don't make since to me, wasn't vacuum testing a big deal back in the day? Why would they make it so hard to do such a simple test?

Well thanks again,

Joel