PCV Hose Connection on 1964 Skylark

[Machine Gun]

I'm replacing the stock Rochester 2GV carburetor with a new Holley. The stock carb has a screw-in tee fitting on its base where the power brake booster and PCV hose are connected. The new carb has only a push-on hose fitting that doesn't come out, so I would have to install an outboard tee to accommodate both hoses. I'd rather not do that because it would result in a bulky and wonky-looking installation.

 

The stock air cleaner won't fit the new carb, so I have to buy a replacement.  Most of the aftermarket air cleaner housings have a provision to add a PCV fitting to the base, where the crankcase vapors would be fed into the housing, bypassing the air cleaner element. I prefer to route the crankcase vapors that way.  I don't see any downside to that option. Any reason that might not be a good idea?

[Aaron65]

The PCV valve needs to see engine vacuum, so the port at the base of the carb is really your only option.  The fittings on air cleaners are for "closed" PCV systems; in other words, they're connected to the breather so there is no escape path for the crankcase vapors to reach the environment.  There's nothing wrong with your going to a closed system, but the PCV valve will still need to see full manifold vacuum somehow or it won't work.  I just looked at a diagram of a Holley 2-barrel, and you're right in saying that "splitting" vacuum is the only way to go.  

 

Have you considered finding another 2GV and going through it?  

[Bloo]

A PCV port is special. It needs to mix the incoming air and vapors with the air/fuel coming from the idle jets and transfer ports. Teeing the power brakes into that should work I guess, but the power brakes can be connected to manifold vacuum literally anywhere, and are usually not teed into the PCV port on most cars. There's probably a pipe plug in an intake manifold runner somewhere. Get a right angle hose barb and hook your power brakes there.

 

PCV needs "air in" and "air out" so it ventilates the crankcase. The "air out" is the PCV valve and the PCV port. The "air in" was usually a breather cap in 1964. When they put the hose up to the air cleaner in the 70s, that was the "air in" to the crankcase that had previously been handled by the breather cap.

 

No PCV system can move enough air to ventilate 100% the time. The engine wont tolerate a vacuum leak that big, even with proper mixing in the carburetor. Sometimes PCV systems blow backwards. The vapors come out the breather cap when that happens, and make a mess around the cap. If you have a hose up to the air cleaner housing, it makes the mess in the air cleaner housing instead.

 

Edited December 3, 2022 by Bloo (see edit history)

[EmTee]

1 hour ago, Bloo said:

The vapors come out the breather cap when that happens, and make a mess around the cap. If you have a hose up to the air cleaner housing, it makes the mess in the air cleaner housing instead.

GM tried to control the mess by moving the hose attachment outside the air cleaner element and adding a dedicated PCV filter.

 

[Aaron65]

A place you might considering drawing your power brake booster vacuum from is the fitting that feeds the transmission vacuum modulator (located on the back of the manifold plenum behind the carburetor .  You'd probably have to patch together some fittings there as well, however, and that probably wouldn't look any better than teeing from the PCV port.  It would most likely be a better way to go.

Edited December 3, 2022 by Aaron65 (see edit history)

[Machine Gun]

Thanx, guys for your comments. All things considered I'm going to stay with the stock setup, i.e. split the fitting at the rear of the carburetor to accommodate the brake booster and the PCV connection.

 

@Aaron65The 2GV I'm replacing is the second one that's been on the car. I'm done with that type of carb. Long story.

[Ben Bruce aka First Born]

Done with ALL carbs.  Never have looked back.  

 

  Ben

[Machine Gun]

7 hours ago, Ben Bruce aka First Born said:

Done with ALL carbs.  Never have looked back.  

 

  Ben

I'd like to say the same, but once I eliminate the vomiting carburetor I'm fine with keeping the old technology. I did seriously look into converting to EFI again around ten days ago when the 2GV had another bit of nausea that wouldn't clear up without an unusually long and arduous fight. That was the final straw for me. The only EFI conversion systems I looked into were the Holley Sniper, and the system that you run in your car. The effort to convert to EFI is something I'd be comfortable doing myself, but I'm just not willing to drop that kind of coin into the car if I can avoid it.

[Ben Bruce aka First Born]

Agree, it is pricy.  So far cost has come out to be about $100.00 per year. Will be less per as time marches on.  As I have said before only self induced problems.  

 

  Good luck

 

  Ben