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I've removed the old CCC Quadrajet electronic carb. and Dist.and am installing a Holley 4175 Spread bore.The Holley does not have all of the vacuum lines and vent lines that the Quadrajet has.My main concern is,how do I connect my (vapor) "canister control valve"?There's a large line ,about 3/8 or so that is a vent from the vapor canister through the "Canister control valve" and went to what looks like the Quadrajet fuel bowl .I dont have a line that size on the Holley fuel bowl.If you have had any experience with this and other things related to this change over,advise,direction or leads are greatly appreciated. Thanks to all! Alvan.:patriot:
 

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Most carbs have the lower vents for full time manifold vac and upper vents which are ported.
Just match where the original lines were plumbed to the new carb.
Add adapter's if need be.
 

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Holly Vacuum Connections

Unfortunatley Unless you purchase a direct replacement for your q-jet, The Hollys dont have enough Vacuum hook ups for all the later smog devices. One option is to replace the vacuum fitting plumbed into the top of the intake manifold with a fitting with more nipples of the correct size. GM produced many different ones with the same thread size.
 

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I've removed the old CCC Quadrajet electronic carb. and Dist.and am installing a Holley 4175 Spread bore.The Holley does not have all of the vacuum lines and vent lines that the Quadrajet has.My main concern is,how do I connect my (vapor) "canister control valve"?There's a large line ,about 3/8 or so that is a vent from the vapor canister through the "Canister control valve" and went to what looks like the Quadrajet fuel bowl .I dont have a line that size on the Holley fuel bowl.If you have had any experience with this and other things related to this change over,advise,direction or leads are greatly appreciated. Thanks to all! Alvan.:patriot:

the holley doesnt have a bowl vent like the qjet, the bowl vent was part of the evaporative emison controls and the holley not beng a emissions carb doesnt have it, therefore there is no way you can connect that particular item. The bowl vent on the holley is a small vertical tube up on the air horn. The lack of vacuum ports can be otherwise offset a bit with vacuum tees in the lines.

Keep also in mind that the holley willlikely be very fat (rich) out of the box.
 

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A slight clarification to the above post, the holley does in fact have bowl vents, but they are inside the air filter area. Those are the tubes that stick straight up on the outer circle or the air horn. Because they are located inside the air filter area, there is a natural vacuum in this area when the engine is running and therefore don't need to be connected to the charcoal canister.
 
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