Idle question

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Mar 21, 2011 | 02:15 AM

sckootter16

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Joined: Aug 2008

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From: Butler PA

Idle question

Ok guys I bought a new carb for my 81 f150 straight six. I am goinng to get a vacuum gauge today to set the mixture screw and that happy stuff. Now I looked on the sticker under the hood to see what the rpm's should be set at. Now the sticker says 600 with non AC. ( I dont have AC) Now is that six hundred with the vacuum advance off or is that what the engine should Idle at with the vacuum advance pluged in? Also I didnt see anything that tells me what the fast idle should be set at. Does anyone know any info would help me out greatly thanx.

Mar 21, 2011 | 12:24 PM

Franklin2

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Joined: Jan 2001

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From: Virginia

I have never worked on a inline six. But most Ford v8's have ported vacuum to the dist, so it will not matter. In other words, at idle, if you have ported vacuum, there will be no vacuum on the dist so it will not matter if it's plugged in or not.

Mar 21, 2011 | 05:40 PM

billt28

Fleet Mechanic

Joined: Jan 2011

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From: West Valley City

I believe you should have the vacuum advance hooked up when you set your idle. The fast idle I believe is 1800 cold.

Mar 21, 2011 | 05:41 PM

Greyf100

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Joined: Apr 2009

Posts: 725

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550-600 RPM (in gear w/auto trans)
550-600 RPM w/ man trans

says to set timing and carb adjustments @ ~800 RPM

fast idle i've found to work best ~1500 RPM

as far as ported vs full manifold vacuum..if all the stock emissions stuff is still functioning and intact then ported vacuum, if not i found the best power / MPG to come from full manifold vacuum. This has been true on my stock 6 and the v8 i swapped in.