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Charcoal canister plumbing


SPLATT71MC

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I removed the charcoal canister on my 71 years ago when I swapped over to a Holley carb. I'm thinking about reinstalling it but have no idea on where the purge valve hose routes to on the engine side. I searched this site and Googled for a couple hours yesterday and didn't find the answer I needed.

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Do you have  Factory Assembly manual? The hose routing is in there. If not, what engine do you have  & I'll look it up a little later.

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43 minutes ago, jft69z said:

Do you have  Factory Assembly manual? The hose routing is in there. If not, what engine do you have  & I'll look it up a little later.

It's packed away for our upcoming move. The engine is the original 350 but with a Holley and open element filter.

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3 minutes ago, Rob Peters said:

I'm glad I have a 70 Monte.  Too much plumbing starting in 71.

rob

It got worse in 72. That's why I put EFI in mine....Waayyyyy easier  🤣🥴:nutz:

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Steve , I can't speak to the Holley,, but here is a pic of how mine hooks up on my 70. 

The small hose (left)…………..goes to the ported vacumn on my Edlebrock carb…   I believe that activates the canister valve and opens up to vacate any accumulated vapors stored or held in the charcoal filter… 

The center line………….goes to intake manifold  (behind the carb ) ..

The right ………..goes directly to the metal line that leads back to the fuel tank….  BTW ,,, I'm using a non vented gas cap,    

Also,, I noticed on another thread that your PCV is plumbed to center port… I have mine set up the same…

The diagram above doesn't totally address the question…   It does indicate the line is sharing the canister with the PCV…

I decided to send the center hose back and around carb directly to the intake manifold…. 

Hope this helps...

Ed C. 

Screenshot 2023-03-25 at 9.53.05 PM.png

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The picture reminds me of years ago when the diaphragm (left side Rochester Products) was shot and leaking vacuum.

I purchased a complete new canister assembly and it fit and worked great. I still have the original one someplace.

A few years later I checked and couldn't find one to purchase anymore.

Try this link I just added 4:59 PM Sunday 26 Mar 2023

https://photos.google.com/share/AF1QipNw7j1PsseRuy0UjSaVYq5wjOmD0gm88OjqH67HeEKdGh2b7U9Xo56EI1WtDeS8MA?key=ZFEyem9TeDVia2dTeE9Db0NjTlZaOHR0SDlpazF3

 

 

Edited by stangeba
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As I understand, the 6 cylinder and 2 barrel 70s GM cars came with the simple in and out hoses. The 4 barrel GM engines came with three hoses shown above. (This may not apply to non calif cars… )  IDK.

It was actually a great system…  A lot of performance minded people disconnected and threw them away…  The EEC system was probably the better of tank vent systems. It had everything to do with practicality and zero effect on performance,, but in theory could be somewhat of a milage improvement by burning accumulated fumes from the tanks… 

I'm sure others may disagree,, but I'm not the one trying to figure out which gas cap to use or not use… 🙂 

Ed. 

 

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On 3/25/2023 at 10:06 PM, EVC said:

Steve , I can't speak to the Holley,, but here is a pic of how mine hooks up on my 70. 

The small hose (left)…………..goes to the ported vacumn on my Edlebrock carb…   I believe that activates the canister valve and opens up to vacate any accumulated vapors stored or held in the charcoal filter… 

The center line………….goes to intake manifold  (behind the carb ) ..

The right ………..goes directly to the metal line that leads back to the fuel tank….  BTW ,,, I'm using a non vented gas cap,    

Also,, I noticed on another thread that your PCV is plumbed to center port… I have mine set up the same…

The diagram above doesn't totally address the question…   It does indicate the line is sharing the canister with the PCV…

I decided to send the center hose back and around carb directly to the intake manifold…. 

Hope this helps...

Ed C. 

Screenshot 2023-03-25 at 9.53.05 PM.png

I do recall that the larger line that goes up to the manifold originally went into a tee fitting that was also plumbed to the the PCV and then routed to the carb. It's the small line that because of the carb change that's been stumping me as to where to route it.

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Steve,

The small hose is plumbed directly to the drivers side port on my Edlebrock carb…  as shown below….

I eliminated the PCV tee on my car because of the AC and valve covers…  It was too crowded in that area, so I put my pcv on the passenger side valve cover.(see center port on the carb)   ….

If you look closely,, the canister center line is routed below my radiator hose and now circles back behind the carb directly to a tee put in the manifold….. You can see a red cap I placed in the hose as a port for the timing vacuum checks, and carb adjustment. 

The big line on the Canister goes to the fuel tank expansion / vapor line… This was the way I was advised to hook it up and it seems to work … Sometimes it's frustrating getting three different opinions from three mechanics…..  

Hope this helps… 

Ed. 

 

 

 

 

IMG_0265.jpeg

Screenshot 2023-04-01 at 4.57.36 PM.png

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1 hour ago, EVC said:

 

Steve,

The small hose is plumbed directly to the drivers side port on my Edlebrock carb…  as shown below….

I eliminated the PCV tee on my car because of the AC and valve covers…  It was too crowded in that area, so I put my pcv on the passenger side valve cover.(see center port on the carb)   ….

If you look closely,, the canister center line is routed below my radiator hose and now circles back behind the carb directly to a tee put in the manifold….. You can see a red cap I placed in the hose as a port for the timing vacuum checks, and carb adjustment. 

The big line on the Canister goes to the fuel tank expansion / vapor line… This was the way I was advised to hook it up and it seems to work … Sometimes it's frustrating getting three different opinions from three mechanics…..  

Hope this helps… 

Ed. 

 

 

 

 

IMG_0265.jpeg

Screenshot 2023-04-01 at 4.57.36 PM.png

Thank you, that's a big help.

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On 4/1/2023 at 9:25 PM, EVC said:

BTW,,, The radiator hose shield was an option in 1970… :)  

I love it! That’s the first thing I noticed!

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