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First, lets look at a typical 49-53 8BA Flathead V8,
It's road draft tube
and the back of the intake at/or under the carb
->where the vacuum line/wipers usually resides.
We're all familiar with the The typical 8BA and it's road draft tube,
Did you know that it's actually just a potential gaping 1 1/4" leak into your engines internals?
At the cap/breather, it's sucking in dust, dirt and moisture, at the road draft tube, it's spewing oily residue into and under your hood.
A quick look at the intake, under the carb at the back....
Most 49-53 intakes will have both the small barb (either straight or 90 degree elbow) for your vacuum wipers as well as this plug pictured at lower right.
This plug is where we are gonna plumb our PCV in at..
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Now,
the obvious question here is:
Why not just put a tee into where the wiper tee/port is????
well, you don't want your vacuum wipers and PCV sharing the same vacuum line or port.
The chances of oily residue being transferred directly into your Valuable Vacuum Wipers is high.
-Protect and keep any and all of your vacuum accessories physically separated from your PCV
or risk
sludging them up.
So pull the plug from the back of the intake and head over to NAPA and ask the guy
if he can match up and supply you with a 3/8" barb that matches your threaded pipe plug....
While your there, get 2 feet of actual Emission/fuel line,
don't substitute or come home with vacuum line...
Total cost up here was $4 for the above items, prices will vary...
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The next stop is the local pic-n-pull where you'll need to find a 70's or 80's Ford with PCV system..
We're looking for the oil breather/cap on the valve cover that holds the factory PCV and it's grommet.
They come as both straight up or 90 degree angled PCV valves and the grommet is the same regardless of straight or angled.
The grommet has a lip on it that will help in snugging up the newly
installed PCV valve into the hole were the former road draft tube used to go.
The actual PCV valve can be found from under the hood of a 4.2 liter V8 as found in many Downsized sedans like the 80's LTD ii, Fairmont, or even a late 70's mustang ll.
Or, One from a 6 cylinder in any 80's small car or truck is also acceptable.
Pic N Pull chargd me $1.
Clean and install the grommet and make sure the inner lip isn't kinked
(as evident here on the left (irregular installed shape/opening))
or the Grommet and PCV valve will have a tendency to walk out as you
motor along.
Install the barb and cut the emission hose to size while keeping the line
tucked down and resting on the top of the block (along side your intake).
On the barb, Teflon tape is optional for brass/pipe fittings but since this is a vacuum line I opted for it. -your choice-
Keep things tidy...
The effects of vacuum/pressure are more pronounced at speed/load.
That is where the engine vacuum drops into a pressure.
At idle with the the new PCV line completely plugged at all ends.
and while simulating an open hole at the road draft tube:
16 1/2 inches of vacuum at 3400 feet above sea level.
With the gaping hole into the galley plugged and the PCV installed,
I gained a little better than 1/2 inch vacuum over the
road draft tube/system open valley.
At speed and under load, while the vacuum drops to zero and the crankcase starts to build pressure is where the real difference will be.
Total cost under $6
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