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Discussion Starter #1
Hi Friends !I got a bunch of questions.Before starting,my Elly is a 86 SS,305 w/a four barrel stock (wires going to it) carb.,auto trans.AC,cruise. I was wondering if changing over my electronic distributor (that sends signals to the ECM) to a vacuum advance,high output coil, distributor is a good idea ? Will it increase MPG's ? What other things will it affect and the most cost effective way to handle those problems? With the high output coil,should I increase my plug gap?The new coil comes with a allen wrench for adjusting the the vacuum advance? Can someone clarify what that means ? Thanks, in advance to all replies.
 

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If you're going from ECM to nonECM, you need to change both distro and carb. Both are (original) controlled by ECM.
 

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I did the swap and wouldn't look back for anything !! Go to Mountain Man Carbs and get you a rebuilt non-feedback carb and a good vac advance distributor and a new set of good wires and you're good to go ! You can get Ted or Ardel at Mtn Man to set the carb up for economy/power and it will run flawlessly. I used the MSD dist and wires but there are other good ones also. WP
 

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Discussion Starter #4
HEI and Holley 4175 installed,Now what?

Thanks Guys! I took your advise and changed to a HEI dist.,new 10 mm wires and picked up a Holley 4175 spead bore 4 barrel carb..The Holley does not have all of the vacuum hook ups that the orig. electronic Quadrajet had.I would like very much to plumb in the vapor canister but I'm not sure how to do that.Any suggestions? Thanks
 

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You can T the vacuum canister output to with the PCV line to the carb, which likely will go to the big manifold vacuum location behind the carb on the manifold, or else to the large inlet at the front base of the carb.
 

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Mike if you connect the canister to full manifold vacuum it will suck fumes from the tank all the time. the big connector on the top front of the q-jet where it did connect is not even ported vacuum. It gets a little venturi pull on it is all. You would also have a major vacuum leak/running issues.
A lot of the guys just run the hose down into the wheel well opening and put a fuel filter in the end of it to let it "breathe". It could also be run to the air cleaner if you add a fitting into the base.
 

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Thanks Guys! I took your advise and changed to a HEI dist.,new 10 mm wires and picked up a Holley 4175 spead bore 4 barrel carb..The Holley does not have all of the vacuum hook ups that the orig. electronic Quadrajet had.I would like very much to plumb in the vapor canister but I'm not sure how to do that.Any suggestions? Thanks
That upper connection on the qjet is nothing more than the bowl vent, part of the evaporative controls of your car. the idea was to capture fuel bowl fumes and recycle them when you restart the car. the holley has an atmospheric vent, it just vents to atmosphere inside the air cleaner assembly and cannot be connected to the cannister.
 
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