Hot Rods Help with 327 breather

So I'm running a 327 and I have the separator under the intake. I'm running a manafre intake with 4 2bbl carbs. What's the best thing to do with the hole in the back of the 327? This is something new tome as all my other cars had breathers in the valve covers. I'm running old cal custom covers with no holes. Thanks

 

I wonder if a freeze plug could be installed with a hole drilled through it for a grommet and pvc hooked up....???? Yes???? No????

 

You need to figure out your PCV system. It needs fresh air in (Breather on VC or fill tube) and a vacuum source hooked into that hole, usually the back of the carb

 

I will be running a breather on oil filler use in front of I take.

 

GM had a couple different pcv systems over the years.
This is a fresh air tube circa 64-68, used on most of the higher hp small blocks, it connects the port adjacent to the distributor to the air cleaner base, pc valve threads into oil fill tube in intake manifold with hose going to carb baseplate.
The style of air cleaner(s) will generally dictate the system used.

 

On an early 327 I believe a road draft tube was connected to the hole in the back of the block. A filler pipe with a breather cap went into a hole in the front of the intake manifold. Valve covers were not vented. Not the most efficient design but correct for an early small block.

 

With 4 2bbl carbs and mini air cleaners there is no option to go yo air cleaner. Not sure if a man a fre I take has a port. Will have to look.

 

I feel that you wouldn't want to however there are those two(2) casting bosses visible on the upper side of the intake, they could be drilled and tapped for an NPT thread and a barbed fitting? You'd most likely have better (Consistent) vacuum from there compared to the other ports that can be seen under the carbs on your intake which have not been drilled and tapped as per my earlier post. I've a 6x2 X1 and am reluctant to alter it being an original intake. Last thing I want to do is drill any holes however I require a vacuum source so I'm drilling at the very back and hiding vacuum so it's out of sight and what can be seen will look OEM when finished.

 

Get the 90 degree adapter for the road draft port and run a hose to a PCV valve at the carburetor. Use the filler/breather tube as GM did. This is a factory method used in lieu of the draft tube.

 

4 2bbl carbs.

 

Thanks but I hate to modify an original intake that is pretty rare. I truly appreciate the pics and the input.

 

You could always use 1" tall risers for the carbs with holes drilled and tapped on the side for a vacuum fitting....

 

You should have pipe plugs in the base of your carbs. I would make a manifold for vacuum with 2 90 deg hose fittings where the pipe plugs are and 2 lengths of hose into both legs of a T fitting, then to the draft tube fitting like shown in post #11. In fact that's exactly how I'm going to do it when I get there on mine

 

My thoughts are go for it and see what happens
I think u are on the right track


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You could use a kit that adapts a PCV into the road draft tube, then plumb that to the carburetors. However, it would be best to share the duties across all 4 carbs so that the mixture to each cylinder is equalized. For that, there are brass pipe plugs in the base of the carbs (visible in your picture above). Plumb a series of fittings and piping so that all are connected and then connect the pcv to that. But I would do as Moriarity said and just use a road draft tube & breather cap on an oil fill tube. That would be period correct. It isn't the best way to ventilate an engine, but it will do. You will likely get some fumes emanating from the breather when stopped at a light, or when cruising slow enough that a draft is not created at the draft tube, but that's how all the early Chevy V8's worked.

 

BTW, here's the kit to adapt the road draft to pcv: https://www.danchuk.com/ItemForm.aspx?Item=13282

 

I can't tell from all the pics what they did there. A clone? Well not really as I'm doing some things differently and tires??? You got me there. Bias ply tires on my sc rambler. Not on this car.

 

Thanks very much

 

Thanks agin very much

 

Don't see a problem...

You have two places to release vacuum from, the front tube and the rear breather. You don't say if you are installing a PCV system, thought...others do..!

You can always do what I did when I had a Man-a- Fre in my 56 Chevy... I built my own air filter. Used a BIG Chrysler filter (don't recall what it was originally for), two sheets of aluminum, four of the short Man-a Fre velocity stacks (yes he sold short ones and long ones). Screwed the lower alum sheet to the velocity stacks and used three studs to hold the top to the bottom. Not pretty, but very effective.

I didn't run a PVC system in my car. Just breathers on the rocker covers and the tube in the front of the manifold. And yes, a freeze plug in the back of the block.

If you want vacuum, drill into the connector passage between the carburetor pads. If you want to keep it clean, you can always open a hole...underneath the Man-a-Fre " plate" is it was called (it's not...a manifold as the term implys). I would not go into just one, of the "injector" locations, as you see little volume of vacuum, and it will pulse from just being connected to two cylinders.

Mike