#21  
Old 06-06-2020, 01:44 PM
topfuel67 topfuel67 is offline
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I thought the GM right side up was only found on the 66. I am not an expert to say this as fact. I have restored a 65 set that I think was untouched with upside down GM and now 2 sets of 66. Both sets of 66 had right side up. I would be curious to see any untouched 66s with the upside down GM.

  #22  
Old 06-07-2020, 11:14 AM
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60sstuff 60sstuff is offline
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topfuel,

Do you have a clear photo of the RH (Pass) side of your center carb showing the vacuum line?

BTW, my 66 has all 3 carbs with right side up GM.

Chris.
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1) 65 GTO Survivor. 43,440 Original Miles. “Factory” Mayfair Maize Paint with Black Pinstripe, Black Cordova Top, Black Interior, OEM Numbers Matching Powertrain. Purchased from the Lady that bought it new. Baltimore Built (11A).
2) 66 GTO Survivor. “Factory” Cameo Ivory Paint with Red Pinstripe, Red Interior. OEM Numbers Matching Powertrain. Tri-Power (OEM Vacuum Linkage), Automatic "YR" code (1759 Produced). Fremont Built (01B), with the Rare 614 Option.
  #23  
Old 06-07-2020, 09:27 PM
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Your vacuum line looks correct. I took mine off and blocked it a long time ago, so I don't remember the shape of the line well.

  #24  
Old 06-07-2020, 10:03 PM
topfuel67 topfuel67 is offline
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I'm pretty sure that it was blocked off. I need to order a new vacuum pot before finishing up the details on it.

  #25  
Old 06-07-2020, 10:32 PM
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Since that spark location was for ported vacuum, did both of you convert to normal manifold vacuum or no vacuum advance on your distributor?

Tom V.

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  #26  
Old 06-08-2020, 12:47 PM
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On mine it's no vacuum, but I would like to try the ported. I gave up running any vacuum a long time ago due to the large cams I've been using.

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Old 06-08-2020, 01:02 PM
topfuel67 topfuel67 is offline
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My distributor and engine is stock. I plan to follow the plumbing for a nonAIR setup. So I'm guessing it gets vacuum from the base. My center carb and rear carb have ports on the bases. The end carb doesn't.

  #28  
Old 06-08-2020, 03:42 PM
topfuel67 topfuel67 is offline
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There is a port on the bottom of the center fuel bowl.
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  #29  
Old 06-08-2020, 04:23 PM
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Quote:
Originally Posted by topfuel67 View Post
My distributor and engine is stock. I plan to follow the plumbing for a nonAIR setup. So I'm guessing it gets vacuum from the base. My center carb and rear carb have ports on the bases. The end carb doesn't.
The base for the rear carb is not a drilled hole base on 49 state carbs.
The Front Carb Base is drilled and normally has a vacuum tee for the
Vacuum Reservoir, the vacuum switches, the brake line, and sometimes the trans line. Not sure about the A/C Vacuum line connection.

So I cannot speak with confidence on if the rear carb base had a drilled hole for a vacuum source for some other system on the car.

Tom V.

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  #30  
Old 06-08-2020, 05:17 PM
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Quote:
Originally Posted by topfuel67 View Post
There is a port on the bottom of the center fuel bowl.
That is for the ported vacuum fitting.

  #31  
Old 06-09-2020, 12:43 PM
topfuel67 topfuel67 is offline
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I figured the drilled one would be closer to the brake booster. I think it just gets capped as my car is originally manual brakes. I am going through the book and cleaning it up. I found on page 11-4 a diagram showing my valve covers backwards, so I swapped those around.

  #32  
Old 06-09-2020, 04:47 PM
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The vacuum to the Power Booster needs to be fed by a large line (like a 3/8" line) because if you plumbed the vacuum signal for the booster to the Ported Spark fitting on the carb it would take forever for the vacuum level in the brake booster to be restored after a major brake stop.

Follow the Pontiac Brake Engineers plumbing design when working with that brake option.

Tom V.

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