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I'm installing AC on my newly purchased 64. I noticed the pcv is plumbed into the rear intake runner. I believe that's wrong and it needs to be plumbed into the carb base on my holley. My question is what will this do to the current tuning of my carb? Will it be lean? Rich? No change?
 

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Discussion Starter #2
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The photo makes it look like it is plummed into the passenger side rear runner. The rest is cut off so I can not see how close to the base of the Carb it is. I'd think it its too far down the runner to #4, just that cylinder would be running a bit leaner than the rest. As long as it's accessible to the plenum I'd think that all the cylinders would draw from it and your relocating it from that location to just under the carb (or the carb's baseplate) would have little effect.

I am sure there is an entire chapter on airflow characteristics in the runners where that might make a difference though.
 

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Yes. Move the pcv hose to the base of the carb.
Most carbs are tuned for pcv so not much will change.
It might actually run better.
 

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Typical "64 1/2" Mustangs did not have a PCV at all, they had a road draft tube. When they did have a PCV, it was connected to a pad at the rear of the intake manifold, which had an oil matrix set inside the manifold. The road draft tube connected to the same place. Later in the 65 model year, the tube was connected to the RH valve cover, same as the PCV.

Since you have a PCV now, and an aftermarket intake manifold, the OE setup is not an option.

Questions now- What carburator do you have, and are you now using a carb spacer?
 

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Discussion Starter #6
Typical "64 1/2" Mustangs did not have a PCV at all, they had a road draft tube. When they did have a PCV, it was connected to a pad at the rear of the intake manifold, which had an oil matrix set inside the manifold. The road draft tube connected to the same place. Later in the 65 model year, the tube was connected to the RH valve cover, same as the PCV.

Since you have a PCV now, and an aftermarket intake manifold, the OE setup is not an option.

Questions now- What carburator do you have, and are you now using a carb spacer?
It has a vacuum secondary holley. Im guessing a 650, I'll have to check but I believe no spacer.
 

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Vacuum secondary Holleys usually have a PCV / large vacuum port into the baseplate. Always hook that to the PCV as it dumps the vapors from the crankcase into a central location to be distributed among all cylinders. The port on the runner should be used for power brakes, auto trans, etc.
 

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I'm installing AC on my newly purchased 64. I noticed the pcv is plumbed into the rear intake runner. I believe that's wrong and it needs to be plumbed into the carb base on my holley. My question is what will this do to the current tuning of my carb? Will it be lean? Rich? No change?
People have found the following diagram helpful, so I share ….
Two things. The early PCV systems did not have a tube from the air cleaner to the valve cover cap. Instead, the cap had its own internal filter and the air entered around its edge.
Be sure that the PCV value is connected to the base of the carburetor (or the spacer under it) so that the fumes entering the intake manifold are distributed evenly among all the cylinders.
PCV diagram.gif
 
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