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RE: 69 Merc 390 Vacuum Advance
By AJ - 06/11/2006 1:15:04 PM; IP 65.185.168.111
Interesting... I am not sure what happened, but that valve in the housing is out of the system completely. This is starting to make a little more sense. I wonder if the vacuum switch went bad at one time, and instead of replacing it, it was bypassed.

Can you at least tell me how the two ports on the vacuum advance differ? Currently the outside port is attached to full vacuum at the intake, so I am getting a lot of advance at idle which is giving me problems with my idle speed. The inner port is attached to the timed carb port.

The throttle blades on the carb are completely closed, and I cannot get the idle down. I know it sounds like a vacuum leak, but looking at the vacuum gauge the reading is rock steady.
This thread, so far...
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Collapse <a href=../ForumFE/reply.aspx?ID=27606&Reply=27606><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor27606" onclick="return false;">69 Merc 390 Vacuum Advance</a>&nbsp;-- <font color=#0000ff>AJ, <i>06/11/2006</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=27606', contentMargin: 60, icon: $('anchor27606') }); </script>  69 Merc 390 Vacuum Advance -- AJ, 06/11/2006
Collapse <a href=../ForumFE/reply.aspx?ID=27613&Reply=27606><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor27613" onclick="return false;">RE: 69 Merc 390 Vacuum Advance</a>&nbsp;-- <font color=#0000ff>Royce P, <i>06/11/2006</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=27613', contentMargin: 60, icon: $('anchor27613') }); </script>  RE: 69 Merc 390 Vacuum Advance -- Royce P, 06/11/2006
Collapse <b>RE: 69 Merc 390 Vacuum Advance</b>&nbsp;-- <font color=#0000ff>AJ, <i>06/11/2006</i></font>RE: 69 Merc 390 Vacuum Advance -- AJ, 06/11/2006
Collapse <a href=../ForumFE/reply.aspx?ID=27619&Reply=27606><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor27619" onclick="return false;">I'll bet this is more 'distributor advance' info than you wanted...</a>&nbsp;-- <font color=#0000ff>Mr F, <i>06/11/2006</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=27619', contentMargin: 60, icon: $('anchor27619') }); </script>  I'll bet this is more 'distributor advance' info than you wanted... -- Mr F, 06/11/2006
 RE: I'll bet this is more 'distributor advance' info than you wanted... -- AJ, 06/12/2006
 390 2v A/T: basic advance = 6° @550 rpm; 28-38° @2K rpm [n/m] -- Mr F, 06/13/2006
Collapse <a href=../ForumFE/reply.aspx?ID=27631&Reply=27606><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor27631" onclick="return false;">Yes - pull 'em to set timing. Read these related posts (& threads)...</a>&nbsp;-- <font color=#0000ff>Mr F, <i>06/13/2006</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=27631', contentMargin: 60, icon: $('anchor27631') }); </script>  Yes - pull 'em to set timing. Read these related posts (& threads)... -- Mr F, 06/13/2006
Collapse <a href=../ForumFE/reply.aspx?ID=27637&Reply=27606><img src=../images/reply.png width=30 height=10></a>&nbsp;<a href="#" id="anchor27637" onclick="return false;">RE: Yes - pull 'em to set timing. Read these related posts (& threads)...</a>&nbsp;-- <font color=#0000ff>AJ, <i>06/13/2006</i></font><script type="text/javascript"> new HelpBalloon({ dataURL: 'replyb.aspx?ID=27637', contentMargin: 60, icon: $('anchor27637') }); </script>  RE: Yes - pull 'em to set timing. Read these related posts (& threads)... -- AJ, 06/13/2006
 Best advance varies w/ compression, state-of-tune, fuel type, etc. [n/m] -- Mr F, 06/13/2006
 Here's another 'advance' thread that might come in handy... -- Mr F, 06/13/2006
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