Vacuum Problem

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Aug 8, 2007 | 01:27 AM

sleep_deprived129

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From: Everett, WA

Vacuum Problem

I think I have a problem with the vacuum lines on my truck...somethin hooked up wrong, vacuum advance (has dual vacuum but one seems to do nothin...could that be another problem?) was hooked up to the manifold vacuum, anyone know where I could find vacuum diagrams to show me how everythin should be hooked up? I already tried the library and had no luck there, nothin in my repair manual for the truck...any other ideas?

Aug 8, 2007 | 02:25 PM

bertha66

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From: Central Oregon

I have seen the double vacumn advances in the past, one side was for advance and the other side would retard the dist. I don't know what the retard side was used for and the ones I saw were unhooked. The carb will have a vacumn port that is metered, no vacumn at a idle, that's the one you need.

Aug 9, 2007 | 01:09 AM

Mil1ion

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What engine ?

Aug 9, 2007 | 01:46 AM

NumberDummy

Ford Parts Specialist

Joined: Nov 2006

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From: Simi Valley, CA

1970/72 F100's with a 302 and 3 speed manual or C4 have what Ford calls a "Distributor Modulator" system. It's a can of worms.

The vacuum diagram is shown in section 120.1; Page 7 in the illustration section of the 1964/72 Ford Truck Parts Catalog.

This parts catalog is available on a CD = hipoparts.com

I can have the illustration scanned and sent, but not till Sunday, as the wife is out of town till then.

Last edited by NumberDummy; Aug 9, 2007 at 01:57 AM.

Aug 10, 2007 | 01:14 AM

sleep_deprived129

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From: Everett, WA

oh yeah....forgot to say that....she's got a 302 wit a C4 tranny

Aug 10, 2007 | 01:16 AM

sleep_deprived129

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From: Everett, WA

if you could send that diagram I would greatly appreciate it

Aug 12, 2007 | 02:01 PM

blue68f100

Fleet Mechanic

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From: Piney Woods of East Texas

Normally with dual vacuum port distributer. The retard side goes to the manifold vac. The advanced side goes to a port on the carb that will not have vac at idle. It picks up vacuum as the throttle opens. So as the manifold drops the the carb increases giving you advance through the full throttle band.