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Discussion Starter #1
where does the vacuum inlet on the lower left of the photo go to (rear passenger side of carb.)? This is on a Holley 3400 series? 4160 600cfm (not certain which carb.?) I've since plugged it, which has helped the idle problem, but would like to know what it is for? Found this to be one of the problems on my friends car that I posted about earlier. If you also notice, there is a vacuum line to the right of it that comes out from the top side, and doubles back to another vacuum inlet toward the bottom? Is this correct?

Thanks

http://a4.cpimg.com/image/C8/DD/11934664-9ed5-019000FC-.jpg
 

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the big one on the lower left is for your PCV valve..but it looks like you are using a spacer and have it plugged into that..so just plug the other on the carb..the U-hose is correct for the choke..the blue cap should be where your distributor vacuum line plugs in..put the blue cap where you now have the hose..*LOL* does any of this make sense?..
 

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Teebone expresses one opinion....

I prefer hooking the distributor to the top front connection..it has vacuum only when the throttle is opened (or the idle is waaaaay too high!!)

the large one is for vacuum for the PCV, power brakes, or the vacuum tee on the firewall of later stangs....if its left open, youll have a massive vacuum leak!!

and yes, the wraparound vacuum line is correct
 

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Yes it does (?) /forums/images/icons/crazy.gif hehe!

You can see the hose in front, it is currently going to the distributor vacuum, so your saying this one should be plugged, and then place the hose where the blue cap is now? I think I got it straight! /forums/images/icons/smile.gif
 

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Chevy guys usually run the dizzy where the blue cap goes....

The car will probably warm up faster and run warmer with it hooked to the lower fitting.

Who's right? who can say.....better believe this has been debated HEAVY before!!
 

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I perfer the distributor vacuum hooked to ported vacuum which is where you have it. This gives no vacuum advance at idle but gives vacuum advance at part throttle and above.
 

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The big one on the left is the power brake booster take off, not the PCV. The PCV port is on the front of the carb and is a bit smaller (second biggest one). This information was packed with my Holley SA...
 
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