Distributor Advance

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Dec 7, 2015 | 09:37 AM

avellaneda13

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From: Kernersville, NC

Distributor Advance

Is this were the distributor advance hooks up if not then where?

Dec 7, 2015 | 12:40 PM

1986F150six

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From: Sheffield, AL

That port appears to be below the throttle plate, which would mean that it is to manifold vacuum. On most 70s and up vehicles, the distributor advance is factory set to be triggered by port vacuum. Using a vacuum gauge, check to see if that port has vacuum at idle speed.

Dec 7, 2015 | 01:30 PM

The Frenchtown Flyer

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Some ported taps have some vacuum at idle speed - maybe 5"hg.

Dec 7, 2015 | 01:37 PM

1986F150six

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From: Sheffield, AL

Yes, Sir... the one on the 1970 Carter YF from a 1970 F350, which I use on my 1986 F150, has about 5" @ idle and does not go above approximately 11" at any speed.

Dec 7, 2015 | 02:35 PM

avellaneda13

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From: Kernersville, NC

so was that a yes or no?

Dec 8, 2015 | 09:48 AM

1986F150six

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From: Sheffield, AL

Quote:

Originally Posted by avellaneda13

so was that a yes or no?

First, using a vacuum gauge, determine if there is a vacuum signal from that port at idle speed. If there is no vacuum at idle and vacuum is measured as soon as the speed is raised, that is the correct port for ported vacuum, which is what the factory used, originally.

If that port has vacuum all the time, it can be used, but adjustments to idle speed likely will be required.

I use a Carter YF carburetor from a 1970 F350 and it only has one vacuum port. The vacuum at that port is ~5" Hg @ idle and never gets higher than ~11". It did not allow maximum vacuum advance at the distributor, so it was capped and I use manifold vacuum for the distributor advance.

Dec 9, 2015 | 04:35 PM

roadrash63

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From: nw pa.

Quote:

Originally Posted by 1986F150six

Yes, Sir... the one on the 1970 Carter YF from a 1970 F350, which I use on my 1986 F150, has about 5" @ idle and does not go above approximately 11" at any speed.

Thank you !
I was running ported advance and could not get going faster than 68 !
And I was wanting more power.
When I read about your ported carb vacuum limiting to 11 hg.
I switched to manifold vacuum and was able to reach 80 !
Not that I do this all the time.
Better throttle response at all speeds.
The only negative is the is a small miss at idle now...