Setting timing

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Jun 2, 2019 | 10:51 AM

eric8

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Joined: Feb 2017

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Setting timing

My distributor on my 71 F100 302 has two separate vacuum nipples. One going to carb vacuum and the other going to a solenoid on the back of the manifold. Which one should be plugged for setting initial idle timing?

Jun 2, 2019 | 11:41 AM

Mach428

Cross-Country

Joined: Apr 2017

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The one going to the carb but if the carb vacuum Port is above the throttle plates, there will likely not be vacuum going to it.

Jun 2, 2019 | 01:16 PM

Tedster9

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Joined: Apr 2002

Posts: 19,311

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From: Waterloo, Iowa

Disconnect and plug bofe of 'em at the carb and manifold and then it's not a factor. Set the idle RPM nice and slow while you do this, 500 - 600, so the centrifugal weights aren't pulling more timing in. A lot of people like a pretty fast idle, that's OK though not when actually setting ignition timing, both mechanical and vacuum advance start to pull in just off idle and that will interfere with setting an accurate base ignition timing. Then spool it up and see where it tops out at, this is the important part.